Chemical Formula: (Ca,Na2,K2)3Al6Si10O32·12H2O Name Origin: Named after William Phillips (1775-1829), English mineralogist and founder of the Geological Society of London. Na modifier added by zeolite nomenclature committee.
Phillipsite is a mineral series of the zeolite group; a hydrated potassium, calcium and aluminium silicate, approximating to (Ca,Na2,K2)3Al6Si10O32·12H2O. The members of the series are phillipsite-K, phillipsite-Na and phillipsite-Ca. The crystals are monoclinic, but only complex cruciform twins are known, these being exactly like twins of harmotome which also forms a series with phillipsite-Ca. Crystals of phillipsite are, however, usually smaller and more transparent and glassy than those of harmotome. Spherical groups with a radially fibrous structure and bristled with crystals on the surface are not uncommon. The Mohs hardness is 4.5, and the specific gravity is 2.2. The species was established by A. Lévy in 1825 and named after William Phillips. French authors use the name Christianite (after Christian VIII of Denmark), given by A. Des Cloizeaux in 1847.
Phillipsite is a mineral of secondary origin, and occurs with other zeolites in the amygdaloidal cavities of mafic volcanic rocks: for example in the basalt of the Giants Causeway in County Antrim, and near Melbourne in Victoria; and in Lencitite near Rome. Small crystals of recent formation have been observed in the masonry of the hot baths at Plombires and Bourbonne-les-Bains, in France. Minute spherical aggregates embedded in red clay were dredged by the Challenger from deep sea sedimenary deposits in the Pacific Ocean.
Researchers from the CNRS and the Université de Poitiers, working in collaboration with teams from the Université de Lille 1, Université de Rennes 1, the French National History Museum and Ifremer, have discovered, in clay sediments from Gabon, fossils of the oldest multicellular organisms ever found (Nature, 2010). In total, more than 400 fossils dating back 2.1 billion years have been collected, including dozens of new types. The detailed analysis of these finds, published on June 25, 2014 in PLoS One, reveals a broad biodiversity composed of micro and macroscopic organisms of highly varied size and shape that evolved in a marine ecosystem.
The discovery in 2010 of 250 fossils of complex multicellular organisms dating back 2.1 billion years in a sedimentary bed close to Franceville, in Gabon, drastically changed the scenario of the history of life on Earth. Until then, the oldest known fossils of complex organisms were 600 million years old (Vendobionta from Ediacara in Australia) and it was commonly accepted that, before that period, life on our planet was exclusively made up of unicellular organisms (bacteria, unicellular algae, etc.). With the Franceville discovery, complex life forms made a leap of 1.5 billion years back in time.
The excavations carried out since 2008 by the team of Professor Abderrazak El Albani, geologist at the Institut de chimie des milieux et matériaux in Poitiers (CNRS/Université de Poitiers), have uncovered 400 fossils. The organic origin (biogenicity) of the samples was confirmed using an ion probe to measure the different sulfur isotopes, while X-ray microtomography revealed their internal and external structures. The rapid fossilization of these individuals by the pyritization phenomenon (replacement of their organic matter by pyrite, brought about by bacterial action) conserved their original forms very well.
Several new morphotypes, e.g. circular, elongated, lobed, etc. have been catalogued by the researchers, each including individuals of different size. Their analyses reveal organisms with radial texture and soft gelatinous bodies. Their forms can be smooth or folded, their texture uniform or knobby and their material in one whole piece or partitioned. The highly organized structure and varied sizes of the macroscopic specimens (up to 17 centimeters) suggest an extremely sophisticated means of growth for the period. This complete marine ecosystem was therefore composed of micro and macroscopic organisms, extremely varied in shape and form, living in a shallow marine environment.
Like the biota* of Ediacara in Australia, whose emergence coincided with a sudden increase in oxygen levels in the atmosphere 800 million years ago, the appearance and diversity of the biota in Gabon corresponds to the first peak in oxygen observed between — 2.3 and — 2 billion years ago. This biodiversity apparently died out after this oxygen level suddenly fell. This Gabonese biota raises questions about the history of the biosphere at a planetary scale. The diversity and highly organized structure of the specimens studied suggest that they were already evolved. It is also possible that other forms of life just as old may exist elsewhere on the planet
This study was performed with the support of the Institut de Chimie des Milieux et des Matériaux de Poitiers (CNRS/Université de Poitiers), the Laboratoire Géosystèmes (CNRS/Université Lille 1), the Centre de Recherches Pétrographiques et Géochimiques (CNRS/Université de Lorraine), the Laboratoire Histoire Naturelle de l’Homme Préhistorique (MNHN/CNRS), the Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie (CNRS/UMPC/MNHN/IRD), the Laboratoire de Géosciences de Rennes (CNRS/Université de Rennes 1) which is part of the Observatoire des Sciences de l’Univers de Rennes, the Laboratoire d’Hydrologie et de Géochimie, Strasbourg (CNRS/Université de Strasbourg), and the Ressources Physiques et Ecosystèmes de Fond de Mer department at the lnstitut Carnot Ifremer Edrome.
*A biota is a community of living organisms historically established in a particular geographic region.
Note : The above story is based on materials provided by CNRS.
Geologists have discovered three previously unrecorded volcanoes in volcanically active southeast Australia.
The new Monash University research, published in the Australian Journal of Earth Sciences, gives a detailed picture of an area of volcanic centres already known to geologists in the region.
Covering an area of 19,000 square kilometres in Victoria and South Australia, with over 400 volcanoes, the Newer Volcanics Province (NVP) features the youngest volcanoes in Australia including Mount Schank and Mount Gambier.
Focusing on the Hamilton region, lead researcher Miss Julie Boyce from the School of Geosciences said the surprising discovery means additional volcanic centres may yet be discovered in the NVP.
“Victoria’s latest episode of volcanism began about eight million years ago, and has helped to shape the landscape. The volcanic deposits, including basalt, are among the youngest rocks in Victoria but most people know little about them,”Miss Boyce said.
“Though it’s been more than 5000 years since the last volcanic eruption in Australia, it’s important that we understand where, when and how these volcanoes erupted. The province is still active, so there may be future eruptions.”
The largest unrecorded volcano is a substantial maar-cone volcanic complex — a broad, low relief volcanic crater caused by an explosion when groundwater comes into contact with hot magma — identified 37 kilometres east of Hamilton.
Miss Boyce said the discoveries were made possible only by analysing a combination of satellite photographs, detailed NASA models of the topography of the area and the distribution of magnetic minerals in the rocks, alongside site visits to build a detailed picture of the Hamilton region of the NVP.
“Traditionally, volcanic sites are analysed by one or two of these techniques. This is the first time that this multifaceted approach has been applied to the NVP and potentially it could be used to study other volcanic provinces worldwide.”
The NVP is considered active, as carbon dioxide is released from Earth’s mantle in several areas, where there is a large heat anomaly at depth. With an eruption frequency of one volcano every 10,800 years or less, future eruptions may yet occur.
It’s hoped that this multifaceted approach will lead to a better understanding of the distribution and nature of volcanism, allowing for more accurate hazard analysis and risk estimates for future eruptions.
Note : The above story is based on materials provided by Monash University.
Phenakite (twinned) Mogok, Sagaing District, Mandalay Division, Burma (Myanmar) Miniature, 3.2 x 1.6 x 1.4 cm “Courtesy of Rob Lavinsky, The Arkenstone, www.iRocks.com”
Chemical Formula: Be2SiO4 Locality: Takovaya, Ekaterinburg (Sverdlovsk), Ural Mts, Russia Name Origin: From the Greek phenakos – “deceiver”, in allusion to its similarity to quartz when colorless.
Phenakite or phenacite is a fairly rare nesosilicate mineral consisting of beryllium orthosilicate, Be2SiO4. Occasionally used as a gemstone, phenakite occurs as isolated crystals, which are rhombohedral with parallel-faced hemihedrism, and are either lenticular or prismatic in habit: the lenticular habit is determined by the development of faces of several obtuse rhombohedra and the absence of prism faces. There is no cleavage, and the fracture is conchoidal. The Mohs hardness is high, being 7.5 – 8; the specific gravity is 2.96. The crystals are sometimes perfectly colorless and transparent, but more often they are greyish or yellowish and only translucent; occasionally they are pale rose-red. In general appearance the mineral is not unlike quartz, for which indeed it has been mistaken.
Phenakite is found in high-temperature pegmatite veins and in mica-schists associated with quartz, chrysoberyl, apatite and topaz. It has long been known from the emerald and chrysoberyl mine on the Takovaya stream, near Yekaterinburg in the Urals of Russia, where large crystals occur in mica-schist. It is also found with topaz and amazon-stone in the granite of the Ilmen Mountains in the southern Urals and of the Pikes Peak region in Colorado (USA). Large crystals of prismatic habit have been found in a feldspar quarry at Kragero in Norway. Framont near Schirmeck in Alsace is another well-known locality. Still larger crystals, measuring 1 to 2 in. in diameter and weighing 28 lb (13 kg). have been found at Greenwood in Maine, but these are pseudomorphs of quartz after phenakite.
For gem purposes the stone is cut in the brilliant form, of which there are two fine examples, weighing 34 and 43 carats (6.8 and 8.6 g), in the British Museum. The indices of refraction are higher than those of quartz, beryl or topaz; a faceted phenakite is consequently rather brilliant and may sometimes be mistaken for diamond.
These reefs were built by Cloudina ~548 million years ago, from the Nama Group, Namibia. Credit: Fred Bowyer
It is a remarkable survivor of an ancient aquatic world — now a new study sheds light on how one of Earth’s oldest reefs was formed.
Researchers have discovered that one of these reefs — now located on dry land in Namibia — was built almost 550 million years ago, by the first animals to have hard shells.
Scientists say it was at this point that tiny aquatic creatures developed the ability to construct hard protective coats and build reefs to shelter and protect them in an increasingly dangerous world.
They were the first animals to build structures similar to non-living reefs, which are created through the natural processes of erosion and sediment deposition.
The study reveals that the animals attached themselves to fixed surfaces — and to each other — by producing natural cement composed of calcium carbonate, to form rigid structures.
The creatures — known as Cloudina — built reefs in ancient seas that now form part of Namibia. Their fossilised remains are the oldest reefs of their type in the world.
Cloudina were tiny, filter-feeding creatures that lived on the seabed during the Ediacaran Period, which ended 541 million years ago. Fossil evidence indicates that animals had soft bodies until the emergence of Cloudina.
Findings from the study — led by scientists at the University of Edinburgh — support previous research which suggested that environmental pressures caused species to develop new features and behaviours in order to survive.
Researchers say animals may have developed the ability to build reefs to protect themselves against increased threats from predators. Reefs also provided access to nutrient-rich currents at a time when there was growing competition for food and living space.
Scientists say the development of hard biological structures — through a process called biomineralisation — sparked a dramatic increase in the biodiversity of marine ecosystems.
The study, published in the journal Science, was carried out in collaboration with University College London and the Geological Survey of Namibia. The work was supported by the Natural Environment Research Council, the University of Edinburgh and the Laidlaw Trust.
Professor Rachel Wood, Professor of Carbonate GeoScience at the University of Edinburgh, who led the study, said: “Modern reefs are major centres of biodiversity with sophisticated ecosystems. Animals like corals build reefs to defend against predators and competitors. We have found that animals were building reefs even before the evolution of complex animal life, suggesting that there must have been selective pressures in the Precambrian Period that we have yet to understand.”
Note : The above story is based on materials provided by University of Edinburgh.
Researchers have found that ocean currents slowed 950,000 years ago, triggering a new phase of colder but less frequent ice ages. Credit: Leo Pena
For decades, climate scientists have tried to explain why ice-age cycles became longer and more intense about 900,000 years ago, switching from 41,000-year cycles to 100,000-year cycles. In a new study in the journal Science, researchers found that the deep ocean currents that move heat around the globe stalled or even stopped, possibly due to expanding ice cover in the north. The slowing currents increased carbon dioxide storage in the ocean, leaving less in the atmosphere, which kept temperatures cold and kicked the climate system into a new phase of colder but less frequent ice ages, they hypothesize.
“The oceans started storing more carbon dioxide for a longer period of time,” said Leopoldo Pena, the study’s lead author, a paleoceanographer at Columbia University’s Lamont-Doherty Earth Observatory. “Our evidence shows that the oceans played a major role in slowing the pace of ice ages and making them more severe.”
The researchers reconstructed the past strength of earth’s system of deep-ocean currents by sampling deep-sea sediments off the coast of South Africa, where powerful currents originating in the North Atlantic Ocean pass on their way to Antarctica. How vigorously those currents moved in the past can be inferred by how much North Atlantic water made it that far, as measured by isotope ratios of the element neodymium bearing the signature of North Atlantic seawater. Like a tape recorder, the shells of ancient plankton incorporate this seawater signal through time, allowing scientists to approximate when the currents grew stronger and weaker off South Africa.
They confirmed that over the last 1.2 million years, the conveyor-like currents strengthened during warm periods and weakened during ice ages, as previously thought. But they also discovered that at about 950,000 years ago, ocean circulation weakened significantly and stayed weak for 100,000 years; during that period the planet skipped an interglacial — the warm interval between ice-ages–and when the system recovered it entered a new phase of longer, 100,000-year ice age cycles. After this turning point, the deep ocean currents remain weak during ice ages, and the ice ages themselves become colder, they find.
“Our discovery of such a major breakdown in the ocean circulation system was a big surprise,” said study coauthor Steven Goldstein, a geochemist at Lamont-Doherty. “It allowed the ice sheets to grow when they should have melted, triggering the first 100,000-year cycle.”
Ice ages come and go at predictable intervals based on the changing amount of sunlight that falls on the planet due to variations in earth’s orbit around the sun. Orbital changes alone, however, are not enough to explain the sudden switch to longer ice age intervals.
According to one earlier hypothesis for the transition, advancing glaciers in North America stripped away soils in Canada, causing thicker, longer-lasting ice to build up on the remaining bedrock. Building on that idea, the researchers hypothesize that the advancing ice might have triggered the slowdown in deep ocean currents, leading the oceans to vent less carbon dioxide, which suppressed the interglacial that should have followed. A 2009 study in Science led by Lamont’s Bärbel Hönisch confirmed that carbon dioxide levels dropped sharply at the time.
“The ice sheets must have reached a critical state that switched the ocean circulation system into a weaker mode,” said Goldstein.
A key ingredient in cellphones, headphones, computers and wind turbines, neodymium, it turns out, is also a good way of measuring the vigor of ancient ocean currents at depth. In a 2000 study in Nature, Goldstein and colleagues used neodymium ratios in deep-sea sediment samples to show that ocean circulation slowed during past ice ages. In a follow-up study in Science, they used the same method to show that changes in climate preceded changes in ocean circulation. A trace element in earth’s crust, neodymium washes into the oceans through erosion from the continents, where natural radioactive decay leaves a signature unique to the land mass where it originated.
When Goldstein and his Lamont colleague Sidney Hemming were pioneering this method in the late 1990s, they rarely worried about surrounding neodymium contaminating their samples. The rise of consumer electronics has changed that. “I used to say you could do sample processing for neodymium analysis in a parking lot,” said Goldstein. “Not anymore.”
Note : The above story is based on materials provided by The Earth Institute at Columbia University.
Chemical Formula: LiAl(Si4O10) Name Origin: From the Greek petalon – “leaf” in allusion to the perfect basal cleavage.
Petalite, also known as castorite, is a lithium aluminium phyllosilicate mineral LiAl(Si4O10), crystallizing in the monoclinic system. Petalite is a member of the feldspathoid group. It occurs as colourless, grey, yellow, yellow grey, to white tabular crystals and columnar masses. Occurs in lithium-bearing pegmatites with spodumene, lepidolite, and tourmaline.
Petalite is an important ore of lithium, and is converted to spodumene and quartz by heating to ~500 °C and under 3 kbar of pressure in the presence of a dense hydrous alkali borosilicate fluid with a minor carbonate component. The colorless varieties are often used as gemstones.
Discovered in 1800, type locality: Utö Island, Haninge, Stockholm, Sweden. The name is derived from the Greek word petalon, which means leaf.
Economic deposits of petalite ahre found near Kalgoorlie, Western Australia; Aracuai, Minas Gerais, Brazil; Karibib, Namibia; Manitoba, Canada; and Bikita, Zimbabwe.
The first important economic application for petalite was as a raw material for the glass-ceramic cooking ware CorningWare. It has been used as a raw material for ceramic glazes.
History
Discovery date : 1800 Town of Origin : ILE UTO Country of Origin : SUEDE
Optical properties
Refractive Index: from 1,50 to 1,52 Axial angle 2V: 82-84°
Physical properties
Hardness: 6,50 Density : from 2,41 to 2,42 Color : colorless; white; grey; yellowish grey; yellow; reddish; greenish; pink Luster: vitreous; nacreous Streak : white Break: sub-conchoidal Cleavage : Yes
Salamanders served as hosts: This reconstruction shows how scientists think the fly larvae adhered to the skin of the amphibian. Credit: Yang Dinghua, Nanjing
Researchers from the University of Bonn and from China have discovered a fossil fly larva with a spectacular sucking apparatus.
Around 165 million years ago, a spectacular parasite was at home in the freshwater lakes of present-day Inner Mongolia (China): A fly larva with a thorax formed entirely like a sucking plate. With it, the animal could adhere to salamanders and suck their blood with its mouthparts formed like a sting. To date no insect is known that is equipped with a similar specialised design. The international scientific team is now presenting its findings in the journal eLIFE.
The parasite, an elongate fly larva around two centimeters long, had undergone extreme changes over the course of evolution: The head is tiny in comparison to the body, tube-shaped with piercer-like mouthparts at the front. The mid-body (thorax) has been completely transformed underneath into a gigantic sucking plate; the hind-body (abdomen) has caterpillar-like legs. The international research team believes that this unusual animal is a parasite which lived in a landscape with volcanoes and lakes what is now northeastern China around 165 million years ago. In this fresh water habitat, the parasite crawled onto passing salamanders, attached itself with its sucking plate, and penetrated the thin skin of the amphibians in order to suck blood from them.
“The parasite lived the life of Reilly,” says Prof. Jes Rust from the Steinmann Institute for Geology, Mineralogy and Palaeontology of the University of Bonn. This is because there were many salamanders in the lakes, as fossil finds at the same location near Ningcheng in Inner Mongolia (China) have shown. “There scientists had also found around 300,000 diverse and exceptionally preserved fossil insects,” reports the Chinese scientist Dr. Bo Wang, who is researching in palaeontology at the University of Bonn as a PostDoc with sponsorship provided by the Alexander von Humboldt Foundation. The spectacular fly larva, which has received the scientific name of “Qiyia jurassica,” however, was a quite unexpected find. “Qiyia” in Chinese means “bizarre”; “jurassica” refers to the Jurassic period to which the fossils belong.
A fine-grained mudstone ensured the good state of preservation of the fossil
For the international team of scientists from the University of Bonn, the Linyi University (China), the Nanjing Institute of Geology and Palaeontology (China), the University of Kansas (USA) and the Natural History Museum in London (England), the insect larva is a spectacular find: “No insect exists today with a comparable body shape,” says Dr Bo Wang. That the bizarre larva from the Jurassic has remained so well-preserved to the present day is partly due to the fine-grained mudstone in which the animals were embedded. “The finer the sediment, the better the details are reproduced in the fossils,” explains Dr Torsten Wappler of the Steinmann-Institut of the University of Bonn. The conditions in the groundwater also prevented decomposition by bacteria.
Astonishingly, no fossil fish are found in the freshwater lakes of this Jurassic epoch in China. “On the other hand, there are almost unlimited finds of fossilised salamanders, which were found by the thousand,” says Dr Bo Wang. This unusual ecology could explain why the bizarre parasites survived in the lakes: fish are predators of fly larvae and usually hold them in check. “The extreme adaptations in the design of Qiyia jurassica show the extent to which organisms can specialise in the course of evolution,” says Prof. Rust.
As unpleasant as the parasites were for the salamanders, their deaths were not caused by the fly larvae. “A parasite only sometimes kills its host when it has achieved its goal, for example, reproduction or feeding ,” Dr Wappler explains. If Qiyia jurassica had passed through the larval stage, it would have grown into an adult insect after completing metamorphosis. The scientists don’t yet have enough information to speculate as to what the adult it would have looked like, and how it might have lived.
Note : The above story is based on materials provided by Universität Bonn.
Guatemala’s Pacaya volcano needs monitoring to prevent death and destruction from eruptions and landslides, and Michigan Technological University researchers are helping local residents and government agencies do just that.
As part of a two-year, $100,000 project, Thomas Oommen, Gregory Waite, and Rüdiger Escobar-Wolf have joined their Guatemalan counterparts scouting the countryside around the volcano to come up with the best sites for monitoring equipment. It’s the first step in compiling information to set up equipment for volcanic monitoring, part of a Society of Exploration Geophysicists-Geoscientists Without Borders (SEG-GWB) project.
“The infrastructure is not there,” said Oommen, assistant professor of geological and mining engineering and sciences. “They lack proper instrumentation, and we will overcome this challenge with seismic stations, GPS, high-resolution cameras and other devices to capture the data.”
They’ll also produce permanent displays explaining volcanic hazards and monitoring to inform local people and visiting tourists.
Oommen just returned from Guatemala, where he, geophysicist Waite and geological engineering postdoc Escobar-Wolf met with leadership of that country’s National Institute of Seismology, Volcanology, Meteorology, and Hydrology (INSIVUMEH), which monitors atmospheric, geophysical and hydrological phenomena and makes recommendations in case of natural disasters.
Monitoring Pacaya Volcano
The team also met with a group from the Instituto Geografico Nacional (IGN), which has ongoing studies of ground deformation around Pacaya, to discuss how best to integrate the new instrumentation with their existing monitoring program.
“The idea is to train the local agencies in the use of the equipment, so we can turn it over to them some day,” Oommen said. “The data obtained from this equipment will help several PhD students here to advance research on volcanic hazards.”
In addition to the work with these scientific agencies, a key meeting was held with leaders of the Pacaya National Park, the municipality of the area that surrounds the volcano, and the representatives from National Coordination Agency for Disaster reduction (CONRED), an agency responsible for risk reduction from a variety of hazards.
“These groups were all very keen to cooperate on the monitoring and outreach components of the project,” said Waite. “The success of this project hinges on this collaboration.”
The project also includes funding for thesis projects to be developed by students from San Carlos University in Guatemala, using the data that will be produced by the new monitoring equipment.
“The multidisciplinary approach involving the volcanologists at INSIVUMEH, the administration of the National Park, the academics from the San Carlos University, and collaborators in other agencies has a great potential to further that type of cooperation beyond the scope of this two-year project,” said Escobar-Wolf.
Pacaya is one of the most active volcanoes in Central America, Oommen pointed out.
“It erupted recently, so the project is timely,” he said. “They’ve had to evacuate 9,000 people 11 times in 24 years. These are large events.”
He said that real-time streaming of data can help prevent a catastrophic event, especially with better monitoring of data. It’s part of volcanic research that goes back some fifty years.
“[Professor Emeritus] Bill Rose actually started this work in Guatemala in the 1960s,” Oommen said. “This is a continuation of natural hazard reduction with a humanitarian focus.”
“I got my undergraduate degree at the San Carlos University and worked for CONRED before coming to Michigan Tech” said Escobar-Wolf. “I also worked with INSIVUMEH at Pacaya and other volcanoes, and I first came in contact with Tech researchers and students, led by Bill Rose. It is very rewarding to collaborate in this project with some of the same people I studied and worked with when I was in Guatemala.”
This research-come-full-circle is a three-pronged attack, Oommen said: build the capacities of local emergency agencies, improve understanding of volcanic hazards at Pacaya, and validate and advance the remote-sensing-based research, including graduate student research back on the Michigan Tech campus.
Note : The above story is based on materials provided by Michigan Technological University
Chemical Formula: CaTiO3 Locality: Achmatovsk near Kussinsk in the Zlatoust district, Ural mountans, Russia. Name Origin: Named after the Russian mineralogist, L. A. Perovski (1792-1856).
Perovskite (pronunciation: pe’ɹovskaɪt) is a calcium titanium oxide mineral species composed of calcium titanate, with the chemical formula CaTiO3. The mineral was discovered in the Ural Mountains of Russia by Gustav Rose in 1839 and is named after Russian mineralogist Lev Perovski (1792–1856).
It lends its name to the class of compounds which have the same type of crystal structure as CaTiO3 known as the perovskite structure. The perovskite crystal structure was first described by Victor Goldschmidt in 1926, in his work on tolerance factors. The crystal structure was later published in 1945 from X-ray diffraction data on barium titanate by the Irish crystallographer Helen Dick Megaw.
Perovskite is found in contact carbonate skarns at Magnet Cove, Arkansas. It occurs in altered blocks of limestone ejected from Mount Vesuvius. It occurs in chlorite and talc schist in the Urals and Switzerland. It is also found as an accessory mineral in alkaline and mafic igneous rocks, nepheline syenite, melilitite, kimberlites and rare carbonatites. Perovskite is a common mineral in the Ca-Al-rich inclusions found in some chondritic meteorites.
A rare earth-bearing variety, knopite, (Ca,Ce,Na)(Ti,Fe)O3) is found in alkali intrusive rocks in the Kola Peninsula and near Alnö, Sweden. A niobium-bearing variety, dysanalyte, occurs in carbonatite near Schelingen, Kaiserstuhl, Germany.
History
Discovery date : 1839 Town of Origin : ACHMATOVSK, DISTRICT DE SLATOUST, MTS OURAL Country of Origin : RUSSIE ex-URSS
Optical properties
Optical and misc. Properties: Fragile, cassant – Transparent – Opaque – Translucide Refractive Index : 2,34
Physical properties
Hardness: 5,50 Density: 4,01 Color : black; brown; yellow; brown red; grayish black; amber; yellow brown Luster: adamantine; metallic; greasy; unpolished Streak : white; grey Break: sub-conchoidal; irregular Cleavage: Yes
The Soufrière Hills volcano, Montserrat Credit: Dr Henry Odbert
A new special volume documenting volcanology research developed at Montserrat, West Indies and including major contributions from University of Bristol researchers is published this month by the Geological Society of London.
The Eruption of the Soufrière Hills Volcano, Montserrat from 2000 to 2010, edited by G. Wadge, R.E.A. Robertson and B. Voight, comprises 27 substantial chapters that review the development and application of scientific study at the Soufrière Hills Volcano. It follows from an earlier memoir, published in 2002, and represents the most complete collection and description of this extraordinary eruption and the breadth of scientific investigation it has facilitated.
In the mid-1990s, the small island of Montserrat in the Caribbean made international news when the Soufrière Hills Volcano began erupting after about 400 years of inactivity. The ensuing eruption has caused devastation on the island – almost all of the population were displaced and the capital city, Plymouth, has subsequently been destroyed and partly buried by volcanic ash. Unlike many eruptions of its type, the Soufrière Hills eruption has been long-lived, continuing to erupt on and off since 1995.
When the volcano first showed signs of unrest, scientists from all over the world scrambled to make measurements and observations. There has been particularly strong involvement from UK scientists, owing to Montserrat’s status as a UK Overseas Territory. With its unique setting and unusual longevity, the Montserrat eruption has become one of the most important and best-studied eruptions of its type, and has spurned a substantive contribution to volcanological science.
Scientists at the University of Bristol have been central to research on Montserrat, on topics ranging from the physics and chemistry of volcanism to developing monitoring and analysis techniques.
In particular, Professor Willy Aspinall and Professor Steve Sparks pioneered the application of operational quantitative risk assessment for volcanic hazards at Montserrat. The models, which are still used in Montserrat, represent the longest-running and most sophisticated volcanic risk assessment of their kind.
Dr Henry Odbert, a research associate in the School of Earth Sciences and former scientist at the Montserrat Volcano Observatory, has authored several chapters in the memoir, including a review and analysis of cyclic eruptive behaviour – one of the notable characteristics of the Montserrat eruption.
His chapter on geodetic observation on Montserrat, with contributions from Dr Jo Gottsmann and Dr Stefanie Hautmann, presents a comprehensive review of how geophysical study enables us to better understand the deep physical processes of volcanic eruptions. Dr Hautmann leads a chapter describing investigation of the volcanic system using gravity data.
The eruption on Montserrat has enabled scientific study that has yielded substantive contributions to our understanding of how volcanic eruptions work, how we can best monitor and interpret volcanic behaviour, and how to assess and manage the risks posed by volcanic hazards.
Dr Odbert said: “This collection, with significant contribution from researchers at the University of Bristol, presents an overview of the science associated with the eruption on Montserrat, particularly between 2000 and 2010 – the last time the volcano erupted fresh lava. At the time of writing, the volcano continues to indicate that future eruptions are still possible. A major scientific challenge now is to apply our knowledge and understanding of this fascinating volcano to forecast how the eruption may evolve hereafter.”
Note : The above story is based on materials provided by University of Bristol
Co-author Anders Carlson (Oregon State University) conducting field research at the south Greenland ice sheet at its inland margin near Narsaq. The new study by Reyes and colleagues suggests that much of southern Greenland was nearly ice-free during a long period of warmer-than-present climate about 400,000 years ago. Credit: Alberto Reyes
A new study suggests that a warming period more than 400,000 years ago pushed the Greenland ice sheet past its stability threshold, resulting in a nearly complete deglaciation of southern Greenland and raising global sea levels some 4-6 meters.
The study is one of the first to zero in on how the vast Greenland ice sheet responded to warmer temperatures during that period, which were caused by changes in the Earth’s orbit around the sun.
Results of the study, which was funded by the National Science Foundation, are being published this week in the journal Nature.
“The climate 400,000 years ago was not that much different than what we see today, or at least what is predicted for the end of the century,” said Anders Carlson, an associate professor at Oregon State University and co-author on the study. “The forcing was different, but what is important is that the region crossed the threshold allowing the southern portion of the ice sheet to all but disappear.
“This may give us a better sense of what may happen in the future as temperatures continue rising,” Carlson added.
Few reliable models and little proxy data exist to document the extent of the Greenland ice sheet loss during a period known as the Marine Isotope Stage 11. This was an exceptionally long warm period between ice ages that resulted in a global sea level rise of about 6-13 meters above present. However, scientists have been unsure of how much sea level rise could be attributed to Greenland, and how much may have resulted from the melting of Antarctic ice sheets or other causes.
To find the answer, the researchers examined sediment cores collected off the coast of Greenland from what is called the Eirik Drift. During several years of research, they sampled the chemistry of the glacial stream sediment on the island and discovered that different parts of Greenland have unique chemical features. During the presence of ice sheets, the sediments are scraped off and carried into the water where they are deposited in the Eirik Drift.
“Each terrain has a distinct fingerprint,” Carlson noted. “They also have different tectonic histories and so changes between the terrains allow us to predict how old the sediments are, as well as where they came from. The sediments are only deposited when there is significant ice to erode the terrain. The absence of terrestrial deposits in the sediment suggests the absence of ice.
“Not only can we estimate how much ice there was,” he added, “but the isotopic signature can tell us where ice was present, or from where it was missing.”
This first “ice sheet tracer” utilizes strontium, lead and neodymium isotopes to track the terrestrial chemistry.
The researchers’ analysis of the scope of the ice loss suggests that deglaciation in southern Greenland 400,000 years ago would have accounted for at least four meters – and possibly up to six meters – of global sea level rise. Other studies have shown, however, that sea levels during that period were at least six meters above present, and may have been as much as 13 meters higher.
Carlson said the ice sheet loss likely went beyond the southern edges of Greenland, though not all the way to the center, which has not been ice-free for at least one million years.
In their Nature article, the researchers contrasted the events of Marine Isotope Stage 11 with another warming period that occurred about 125,000 years ago and resulted in a sea level rise of 5-10 meters. Their analysis of the sediment record suggests that not as much of the Greenland ice sheet was lost – in fact, only enough to contribute to a sea level rise of less than 2.5 meters.
“However, other studies have shown that Antarctica may have been unstable at the time and melting there may have made up the difference,” Carlson pointed out.
The researchers say the discovery of an ice sheet tracer that can be documented through sediment core analysis is a major step to understanding the history of ice sheets in Greenland – and their impact on global climate and sea level changes. They acknowledge the need for more widespread coring data and temperature reconstructions.
“This is the first step toward more complete knowledge of the ice history,” Carlson said, “but it is an important one.”
More information:
South Greenland ice-sheet collapse during Marine Isotope Stage 11, Nature, dx.doi.org/10.1038/nature13456
Note : The above story is based on materials provided by Oregon State University
Chemical Formula: NaCa2(HSi3O9) Locality: Prospect Park quarry, northern New Jersey. Name Origin: From the Greek pektos – “compacted” and lithos – “stone.”Pectolite is a white to gray mineral, NaCa2(HSi3O9), sodium calcium inosilicate hydroxide. It crystallizes in the triclinic system typically occurring in radiated or fibrous crystalline masses. It has a Mohs hardness of 4.5 to 5 and a specific gravity of 2.7 to 2.9. The gemstone variety, larimar, is a pale to sky blue.
It was first described in 1828 at Mt. Baldo, Trento Province, Italy and named from the Greek pektos – “compacted” and lithos – “stone”.
It occurs as a primary mineral in nepheline syenites, within hydrothermal cavities in basalts and diabase and in serpentinites in association with zeolites, datolite, prehnite, calcite and serpentine. It is found in a wide variety of worldwide locations.
History
Discovery date : 1828 Town of Origin : MT. BALDO et MT. MONZONI Country of Origin : ITALIE
Optical properties
Optical and misc. Properties: Transparent – Translucide – Luminescent, fluorescent – Gemme, pierre fine – Opaque – Macles possibles – Triboluminescent – Fragile, cassant – Tenace – Refractive Index: from 1,59 to 1,64 Axial angle 2V: 50-63°
Physical properties
Hardness : from 4,50 to 5,00 Density: from 2,84 to 2,90 Color : colorless; white; grey white; whitish; grayish; grey; pink; green; red; yellowish Luster : subvitreous; silky; nacreous Streak: white Break : conchoidal; irregular Cleavage: Yes
In the hunt for early life, geobiologists seek evidence of ancient microbes in the form of trace fossils – geological records of biological activity – embedded in lavas beneath the ocean floor. Filamentous titanite (a calcium titanium silicate mineral) microtextures found in 3.45 billion-year-old volcanic pillow lavas of the Barberton greenstone belt of South Africa, have been argued previously2 to be Earth’s oldest trace fossil, representing the mineralized remains of microbial tunnels in seafloor volcanic glass. However, scientists at the University of Bergen, Norway have reported new data based on in situ U-Pb (uranium-lead) dating, metamorphic temperature mapping constraints and morphological observations that bring the biological origin of these fossils into serious question.
The new age determined for the titanite microtextures is much younger than the eruptive and seafloor hydrothermal age of the previously proposed bioalteration model. As a result, the researchers have analyzed these fossils’ syngenicity (age as estimated by a textural, chemical, mineral, or biological feature formed at the same time as its encapsulating material) and biogenicity (any chemical and/or morphological signature preserved over a range of spatial scales in rocks, minerals, ice, or dust particles that are uniquely produced by past or present organisms). The scientists conclude that the oldest bona fide biogenic trace fossil now reverts to roughly 1.7 Ga microborings in silicified stromatolites found in China, and that the search for subsurface life – both on the early Earth as well as in extraterrestrial mafic–ultramafic rocks1, such as Martian basalts – be based not only on new biosignatures, but on new detection techniques as well.
Dr. Eugene G. Grosch discussed the paper that he and Dr. Nicola McLoughlin published in Proceedings of the National Academy of Sciences. “Previous work2 argued that titanite formed inside, or infilled, hollow tubes initially proposed to have been made by microbes living in the volcanic subseafloor at around 3.472 billion years ago – but the age estimate of the trace fossil formation and mineralization was not well constrained,” Grosch tells Phys.org. “In our PNAS study we took a critical approach, conducting a syngenicity test of the previous bioalteration model to determine if the titanite did indeed form 3.472 billion years ago during subseafloor hydrothermal alteration and Paleoarchean glass microbial bioalteration.” Using two laser-ablation inductively coupled plasma mass spectrometry, or LA-ICP-MS, instruments (single- and multi-collector), and a uranium-to-lead isotopic decay radiometric system, the scientists dated the titanite at roughly 2.9 billion years old – too recent for the titanite to be syngenetic with the 3.472 billion year old bioalteration model. “This was a challenge,” Grosch adds, “because these rocks are extremely old, so we had to be careful to take into account common lead in the titanite mineral.”
In order to potentially make a claim or confirm earliest candidate traces of life in Archean subseafloor environments, the researchers propose that careful geological work should first be conducted and that low-temperature metamorphic events should be completely characterized in Archean greenstone belt pillow lavas (bulbous, spherical, or tubular lobes of lava attributed to subaqueous extrusion). They accomplished this by using a new quantitative electron microprobe microscale mapping technique to map the composition of different minerals associated with the putative titanite filaments. In addition, they applied an inverse thermodynamic modelling approach to the mineral chlorite in the maps and calculated a metamorphic temperature map in the matrix surrounding a candidate titanite trace fossil. Their results showed, for the first time, constraints on metamorphic conditions and that on a microscopic scale, the best-developed titanite filaments were associated with the low-temperature microdomains. “This discovery indicates a cooling history around the titanite filaments, and supports an abiotic – that is, not associated with life – mineral growth mechanism at 2.9 Ga,” Grosch explains. “This proves that the titanite was a result of much younger metamorphic growth and not related to the posited biological activity in the 3.472 Ga bioalteration model constructed by previous investigators. Moreover, filamentous titanite cannot be used as a biosignature because it has failed a wide range of syngenicity and biogenicity tests.”
Finding that these titanite microtextures exhibit a morphological continuum bearing no similarity to candidate biotextures found in the modern oceanic crust also supports their conclusions. “One of the main lines of evidence in our study that questions the biogenicity of the titanite microtextures is the huge range of shapes and sizes that they exhibit,” Grosch tells Phys.org. “This contradicts the general principle accepted by palaeontologists that a fossil population should show a restricted size distribution that reflects biological control on growth, as opposed to self-organizing abiotic processes that do not show restricted size distributions. Furthermore, we argue that the growth continuum in the Barberton titanite microtextures, from oval-shaped hornfelsic (thermally metamorphosed rock) structures with few projections to coalesced oval-shaped structures that progress into bands with increasing number and size of filamentous projections, records an abiotic, metamorphic growth process and not the earlier seafloor trace fossil model. Lastly, in contrast to the microtextures of argued biogenic origin from the modern oceanic crust which do show a narrow size distribution and specific shapes, the Barberton microtextures show a much greater range in sizes – at least an order of magnitude greater – and a much larger spectrum of morphologies.”
To address the challenges encountered in their research, Grosch says that the key insight was that all the tests and in situ data indicated that titanite microtextures failed as a biosignature that represents Earth’s oldest trace fossil. “In addition,” he notes, “there are no organics such as decayed carbon or nitrogen associated with the titanite; the size, shape and distribution of the filamentous titanite are all not compatible with that expected for a biogenic population; the age is much too young at 2.8-2.9 billion years ago; and the quantitative petrological mapping indicates a thermal history compatible with an abiotic growth of titanite filaments, not as infilling minerals as previous studies have proposed.” (Petrology is the branch of geology that studies the origin, composition, distribution and structure of rocks.). Grosch concludes that filamentous titanite microtextures, such as those in the Barberton pillow lavas, can no longer be used as a biological search image for life in Archean metavolcanic glass, and that other search images combined with morphological and biogeochemical evidence for early life need to be found. “If we want to make a robust case for early life preserved in Archean volcanic rocks or any other ancient rock, we need to look for early morphological and biogeochemical biosignatures – but we also have to combine these with high-resolution 2- and 3-dimensional mapping and reconstructions,” he points out. “We also need to prove a ‘fossil’ is a very early structure preserved in the rock and not a later abiotic feature. We need to find new ways to carefully peel back layers of deep geological time and eliminate all abiotic scenarios first before we can be sure of an early body or trace fossil.”
Regarding biogeochemical traces of life on early Earth, the scientists have found that the sulfur isotopes of microscopic sulfide minerals found in the Barberton pillow lavas have unusually large fractionations (the ratio of light to heavy 32 to 34 sulfur atoms), and that this could record the activities of sulfur-based microbes in the Archean subseafloor. “In a previous study led by co-author Dr. Nicola McLoughlin3,” Grosch continues, “we suggested that these types of chemical signatures need to be further investigated as possible alternative evidence for an early subseafloor biosphere on early Earth. Such signatures are known from ancient sediments, where they are widely accepted as evidence of early sulfur based life forms – but this was the first and earliest evidence from subseafloor volcanic rocks.” In a previous work3, the scientists state that alternatives such as sulfur isotope fractionations recorded by basalt-hosted sulfides could be more promising in the search for evidence of ancient life. Grosch notes that today’s microbes use the light isotope in their metabolic pathways, such as 32S in microbial sulfate reduction. As a consequence, when seawater sulfate is used for energy by these microbes, the mineral pyrite, or FeS2, is formed as a reaction byproduct. As such, the fraction in the sulfur 32S/34 S ratio is large and can therefore be measured in the FeS2. “We can measure the pyrite 32S/34S ratio relative to an international standard derived from meteoritic sulfide and use the degree of fractionation as a biogeochemical marker. That’s a wide range of 32/34S ratios – and a negative range is a good geochemical sign of possible early Archean microbial life.”
Grosch also discusses the prospect of looking for signs of early life in extraterrestrial mafic-ultramafic rocks by adopting a highly critical and multi-pronged analytical testing approach towards biogenicity. “Until one day in the future when space missions return samples from Mars, we have to use satellite-based remote sensing techniques to investigate the abundant mafic-ultramafic rocks found on Mars.” (He adds that Martian meteorites are also of interest – particularly a group called Nakhalites that contain igneous minerals and are believed to show evidence of aqueous alteration and possible biosignatures) A good strategy,” he says, “would be to focus on locations where there’s strong evidence for water-rock interaction and preserved organic carbon, because these sites may have chemical gradients that could help sustain microbes.” In fact, in another study4 the scientists explore how microscale mapping of the low-temperature minerals in such rocks could be used to investigate their alteration history and to evaluate the possibility of preserving chemical and textural traces of life in extra-terrestrial mafic-ultramafic rocks.
“We need to look carefully for possible microbe morphologies and possible preserved microbial activity in extraterrestrial samples. We need to apply new thermodynamic and high-resolution analytical petrological techniques such as metamorphic, nano-SIMS and soft X-ray (synchrotron) mapping techniques to understand very low-temperature conditions of hydrothermal alteration and possible signs and preservation of microbial life in samples from other rocky planets, such as Mars.”
Moving forward, Grosch identifies the key next steps in their research and other possible innovations:
Extensive geological mapping of the Barberton Greenstone Belt, South Africa to identify alternative locations and evidence for early microbial life
Further studies of recent seafloor volcanic glass to establish if the microtunnels are really the product of microbial life – and if so, what type of microorganisms are involved
Further geochronological work – that is, radiometric dating to better establish the timing of geological events and age of different environments in these ancient Archean rocks
Development and refinement of thermodynamic models, in metamorphic petrology tools and in situ geochemistry techniques to better characterize and test microscopic textural and chemical evidence of putative life in Archean rocks
Apply and compare multiple high-resolution techniques to candidate biosignatures in ancient rocks
Grosch notes that there are other areas of research that might benefit from their study. “In the field of paleontology, fossil experts now need to go and look for the oldest robust trace fossils – and while that our study questions the evidence in ancient metamorphic pillow lavas, and that the oldest bona fide candidate trace fossil comes from 1.7 billion year old rocks in China, if paleontologists look harder and in the right places, they may find trace fossils and evidence of microbial activities in older rocks, such as silicified seafloor sediments or in shallow marine Archean environments. In addition, from our findings we propose to astrobiologists and planetary scientists that looking for filamentous titanite microtextures as an extraterrestrial biosignature is misleading, and therefore they should seek other evidence for subsurface life on other wet rocky planets in our solar system – especially Mars – and possibly beyond.”
More information:
Reassessing the biogenicity of Earth’s oldest trace fossil with implications for biosignatures in the search for early life, Proceedings of the National Academy of Sciences, Published online before print on May 27, 2014, doi:10.1073/pnas.1402565111
The passageway that links the Pacific Ocean to the Indian Ocean
The passageway that links the Pacific Ocean to the Indian Ocean is acting differently because of climate change, and now its new behavior could, in turn, affect climate in both ocean basins in new ways.
UH Mānoa physical oceanographer James Potemra is co-author of a study led by Janet Sprintall of Scripps Institution of Oceanography at UC San Diego. The scientists have found that the flow of water in the Indonesian Throughflow – the network of straits that pass Indonesia’s islands – has changed since the late 2000s under the influence of dominant La Niña conditions. The flow has become more shallow and intense in the manner that water flows through a hose that has become kinked. The study suggests that human-caused climate change might make this characteristic a more dominant feature of the throughflow, even when El Niño conditions return.
Sprintall and colleagues have spent more than a decade understanding the dynamics of the throughflow, an ocean region that acts like a cable sending information between two electronic devices. The Indonesian seas are the only tropical location in the world where two oceans interact in this manner. The throughflow has an effect on the climate well beyond its boundaries, playing a role in everything from Indian monsoons to the El Niño phenomena experienced by California.
“This is a seminal paper on a key oceanographic feature that may have great utility in climate research in this century,” said Eric Lindstrom, a physical oceanography program scientist who co-chairs the Global Ocean Observing System Steering Committee at NASA, which funded Sprintall’s portion of the study. “The connection of the Pacific and Indian oceans through the Indonesian Seas is modulated by a complex circulation, climate variations, and sensitive ocean-atmosphere feedbacks. It’s a great place for us to sustain ocean observations to monitor potential changes in the ocean’s general circulation under a changing climate.”
Sprintall, a physical oceanographer at Scripps Oceanography, said this new research starts a new chapter in the history of the throughflow, one characterized by the changed variables created by global warming.
“Now that we have a better understanding of how the Indonesian Throughflow responds to El Niño and La Niña variability, we can begin to understand how this current behaves in response to changes in the trade wind system that are brought on through anthropogenic climate change,” Sprintall said. “Changes in the amount of warm water that is carried by the throughflow will have a subsequent impact on the sea surface temperature and so shift the patterns of rainfall in the whole Asian region.”
The study, “The Indonesian seas and their role in the coupled ocean-climate system,” appeared in the June 22 advance online publication of the journal Nature Geoscience.
In previous work over the past decade, Sprintall and colleagues from several countries have revised earlier thinking that most of the action in the throughflow was just at the surface where winds and waves interact. In fact, the flow often runs as much as 100 meters (328 feet) below the surface and features upwellings and other strong vertical flows of water. Model simulations have suggested that without this flow, the Indian Ocean would be generally colder at the surface as the Pacific would not be able to route warm water to it as efficiently.
These computer-generated scenarios have helped researchers forecast what could be happening as a consequence of human-caused climate change. Since the mid-twentieth century, scientists have noticed that Pacific Ocean tradewinds are weakening. The tradewinds help push Pacific Ocean water toward the throughflow and ultimately to the Indian Ocean. This corresponds to a predicted general slowdown of global thermohaline circulation – the flow of heat and salt around the world’s oceans.
The researchers found that as a strong El Niño regime begun in the late 1990s slowly yielded to La Niña conditions in the middle of the following decade, the nature of the throughflow changed. The strongest currents became shallower and faster through the main component of the throughflow, the Makassar Strait that runs between the Indonesian islands of Kalimantan and Sulawesi.
La Niña and El Niño are characterized in part by the location of a warm pool of surface water in the Pacific Ocean. Warm water in the western Pacific near Indonesia is usually associated with La Niña and warm water in the eastern equatorial Pacific with El Niño.
The researchers said the study provides an important consideration that should guide the intense marine conservation efforts that are underway in Indonesia and neighboring countries. The nature of the throughflow has a direct influence on what nutrients get delivered to marine organisms in the region and in what quantity. The work also suggests that ongoing regular observations of what is happening in the throughflow are a necessity going forward.
More information:
“The Indonesian seas and their role in the coupled ocean–climate system.” Janet Sprintall, et al. Nature Geoscience (2014) DOI: 10.1038/ngeo2188. Received 02 January 2014 Accepted 21 May 2014 Published online 22 June 2014
Note : The above story is based on materials provided by University of Hawaii at Manoa
Parisite-(Ce) Locality: East Kemptville Tin mine, East Kemptville, Argyle, Yarmouth Co., Nova Scotia, Canada Source: Donald Doell
Chemical Formula: Ca(Ce,La)2(CO3)3F2 Locality: Emerald mines, Muso, columbia. Name Origin: Named for J. J. Paris, mine proprietor at Muzo, north of Bogota, Columbia.
Parisite is a rare mineral consisting of cerium, lanthanum and calcium fluoro-carbonate, Ca(Ce,La)2(CO3)3F2. Parisite is mostly parisite-(Ce), but when neodymium is present in the structure the mineral becomes parisite-(Nd).
It is found only as crystals, which belong to the trigonal or monoclinic pseudo-hexagonal system and usually have the form of acute double pyramids terminated by the basal planes; the faces of the hexagonal pyramids are striated horizontally, and parallel to the basal plane there is a perfect cleavage. The crystals are hair-brown in color and are translucent. The hardness is 4.5 and the specific gravity is 4.36. Light which has traversed a crystal of parisite exhibits a characteristic absorption spectrum.
At first, the only known occurrence of this mineral was in the famous emerald mine at Muzo in Colombia, South America, where it was found by J.J. Paris, who rediscovered and worked the mine in the early part of the 19th century; here it is associated with emerald in a bituminous limestone of Cretaceous age.
Closely allied to parisite, and indeed first described as such, is a mineral from the nepheline-syenite district of Julianehaab in south Greenland. To this the name synchysite has been given. The crystals are rhombohedral (as distinct from hexagonal; they have the composition CeFCa(CO3)2, and specific gravity of 2.90. At the same locality there is also found a barium-parisite, which differs from the Colombian parisite in containing barium in place of calcium, the formula being (CeF)2Ba(CO3)3: this is named cordylite on account of the club-shaped form of its hexagonal crystals. Bastnasite is a cerium lanthanum and neodymium fluoro-carbonate (CeF)CO3, from Bastnas, near Riddarhyttan, in Vestmanland, Sweden, and the Pikes Peak region in Colorado, U.S.A.
Discovery date : 1845 Town of Origin: DISTRICT DE MUZO, BOGOTA Country of Origin : COLOMBIE
Physical properties
Hardnes : 4,50 Density : 4,36 Color : brownish yellow; brown; yellow; grayish yellow Luster: vitreous; resinous; nacreous Streak : white Break : sub-conchoidal; splintery Cleavage : Yes
Photos :
Parisite-(Ce) Muzo Mine, Boyaca Department, Colombia (TYPE LOCALITY) Small Cabinet, 6.3 x 5.0 x 3.5 cm “Courtesy of Rob Lavinsky, The Arkenstone, www.iRocks.com”
A collaborative research team has discovered an important link between the eruption of Earth’s hottest lavas, the location of some of the largest ore deposits and the emergence of the first land masses on the planet – the continents – more than 2500 million years ago.
The research team includes researchers from the Centre for Exploration Targeting at The University of Western Australia and Curtin University, which are key nodes of the ARC Centre of Excellence for Core to Crust Fluid Systems, in collaboration with colleagues from CSIRO and the Geological Survey of Western Australia.
The generation and evolution of the Earth’s continental crust has played a fundamental role in the development of the planet. Its formation modified the composition of the Earth’s interior, contributed to the establishment of the atmosphere and led to the creation of ecological niches, essential for early life.
The study, published today in the prestigious international journal Proceedings of the National Academy of Sciences, used a combination of different radiogenic isotopes to show that in the early evolutionary stages of our planet, the formation and stabilisation of continents also controlled the location and extent of major komatiite volcanic eruptions.
Study co-author Professor Marco Fiorentini said komatiites were ultra-high temperature lavas that erupted in large volumes more than 2500 million years ago (Archean eon), but only very rarely since.
“They are the signature rock type of a hotter Earth in the primordial stages of its evolution, and provide the most direct link between the Earth’s interior and the Earth’s surface,” Professor Fiorentini said.
“They locally contain some of the largest known deposits of metals such as nickel, cobalt and platinum. Due to the unique geological processes that led to the formation of komatiites, they represent a rare window into the development of the innermost parts of our planet, notably the deep and inaccessible mantle and core.”
Focusing on the Yilgarn Craton of Western Australia as a natural laboratory, the research team combined sophisticated geochemical and isotopic techniques to unveil the progressive development of an Archean micro-continent.
Results from this study show that in the ancient Earth, relatively small crustal ‘blocks’, not unlike modern micro-plates, progressively developed and coalesced to form larger continental masses, called cratons, Professor Fiorentini said.
“This ‘cratonisation’ process formed deep roots to the continental land masses, extending more than 200km deep into the Earth,” he said. “The roots drove the hottest and most voluminous komatiite eruptions to the edge of established continental blocks. The ability to map these continental blocks through time points to the location where major metal deposits formed in these lavas.”
As a result, the dynamic evolution of the early continents directly influenced where deep mantle material was added to the Archean crust, oceans and atmosphere.
The complex interaction between the eruptions of some of the hottest lavas that ever existed on the planet, with the emergence of the first continents, provided a fundamental control on the distribution of major ore deposits. It also had an irreversible impact on the nature of the terrestrial biosphere-hydrosphere-atmosphere.
Reference:
David R. Mole, Marco L. Fiorentini, Nicolas Thebaud, Kevin F. Cassidy, T. Campbell McCuaig, Christopher L. Kirkland, Sandra S. Romano, Michael P. Doublier, Elena A. Belousova, Stephen J. Barnes, and John Miller. “Archean komatiite volcanism controlled by the evolution of early continents.” PNAS 2014 ; published ahead of print June 23, 2014, DOI: 10.1073/pnas.1400273111
The Darling is a major tributary of the Murray-Darling system
The Darling River is the third longest river in Australia, measuring 1,472 kilometres (915 mi) from its source in northern New South Wales to its confluence with the Murray River at Wentworth, New South Wales. Including its longest contiguous tributaries it is 2,844 km (1,767 mi) long, making it the longest river system in Australia.
The Darling River is the outback’s most famous waterway. The Darling has been in poor health, suffering from overuse of its waters, pollution from pesticide runoff and prolonged drought. In some years it has barely flowed at all. The river has a high salt content and declining water quality. Increased rainfall in its catchment in 2010 has improved flow, but the health of the river will depend on long-term management.
The Division of Darling, Division of Riverina-Darling, Electoral district of Darling and Electoral district of Lachlan and Lower Darling were named after the river.
The Queensland headwaters of the Darling (the area now known as the Darling Downs) were gradually colonised from 1815 onward. In 1828 the explorer Charles Sturt and Hamilton Hume were sent by the Governor of New South Wales, Sir Ralph Darling, to investigate the course of the Macquarie River. He discovered the Bogan River and then, early in 1829, the upper Darling, which he named after the Governor. In 1835, Major Thomas Mitchell travelled a 483 km portion of the Darling River. Although his party never reached the junction with the Murray River he correctly assumed the rivers joined.
In 1856, the Blandowski Expedition set off for the junction of the Darling and Murray Rivers to discover and collect fish species for the National Museum. The expedition was a success with 17,400 specimens arriving in Adelaide the next year.
Although its flow is extraordinarily irregular (the river dried up on no fewer than forty-five occasions between 1885 and 1960), in the later 19th century the Darling became a major transportation route, the pastoralists of western New South Wales using it to send their wool by shallow-draft paddle steamer from busy river ports such as Bourke and Wilcannia to the South Australian railheads at Morgan and Murray Bridge. But over the past century the river’s importance as a transportation route has declined.
In 1992, the Darling River suffered from severe cyanobacterial bloom that stretched the length of the river.The presence of phosphorus was essential for the toxic algae to flourish. Flow rates, turbulence, turbidity and temperature were other contributing factors.
In 2008, the Federal government spent $23 million to buy Toorale Station in northern New South Wales, which allowed for the return of eleven gigalitres of environmental flows.
Course
The whole Murray-Darling river system, one of the largest in the world, drains all of New South Wales west of the Great Dividing Range, much of northern Victoria and southern Queensland and parts of South Australia. Its meandering course is three times longer than the direct distance it traverses.
Much of the land that the Darling flows through are plains and is therefore relatively flat, having an average gradient of just 16 mm per kilometre. Officially the Darling begins between Brewarrina and Bourke at the confluence of the Culgoa and Barwon rivers; streams whose tributaries rise in the ranges of southern Queensland and northern New South Wales west of the Great Dividing Range. These tributaries include the Balonne River (of which the Culgoa is one of three main branches) and its tributaries; the Macintyre River and its tributaries such as the Dumaresq River and the Severn Rivers (there are two – one either side or the state border); the Gwydir River; the Namoi River; the Castlereagh River; and the Macquarie River. Other rivers join the Darling near Bourke or below – the Bogan River, the Warrego River and Paroo River.
Darling River at Louth
South east of Broken Hill, the Menindee Lakes are a series of lakes that were once connected to the Darling River by short creeks. The Menindee Lake Scheme has reduced the frequency of flooding in the Menindee Lakes. As a result about 13,800 hectares of lignum and 8,700 hectares of Black box have been destroyed. Weirs and constant low flows have fragmented the river system and blocked fish passage.
The Darling River runs south-south-west, leaving the Far West region of New South Wales, to join the Murray River on the New South Wales – Victoria border at Wentworth, New South Wales.
The Barrier Highway at Wilcania, the Silver City Highway at Wentworth and the Broken Hill railway line at Medindee, all cross the Darling River. Part of the river north of Menindee marks the border of Kinchega National Park. In response to the 1956 Murray River flood a weir was constructed at Menindee to mitigate flows from the Darling River.
The north of the Darling River is in the Southeast Australia temperate savanna ecoregion and the south west of the Darling is part of the Murray Darling Depression ecoregion.
Population centres
Major settlements along the river include Brewarrina, Bourke, Louth, Tilpa, Wilcannia, Menindee, Pooncarie and Wentworth. Wentworth was Australia’s busiest inland port in the late 1880s.
Navigation by steam boat to Brewarrina was first achieved in 1859. Brewarrina was also the location of inter-tribal meetings for Indigenous Australians who speak Darling and live in the river basin. Ancient fish traps in the river provided food for feasts. These heritage listed rock formations have been estimated at more than 40,000 years old making them the oldest man-made structure on the planet.
Note : The above story is based on materials provided by Wikipedia
Chemical Formula: Fe2+Al2(PO4)2(OH)2·8H2O Locality: Llallagua, Potosi, Bolivia. Name Origin: Named for the chemical similarity to vauxite. Polymorph of metavauxite.
Earthquake progression with time along the North Anatolian Fault.
Is one of the world’s great cities due to be struck by a serious earthquake? Ekbal Hussain describes how scientists are working to make sure Istanbul is prepared for the dangers that may be on the way.
Straddling the European and Asian borders Istanbul is an ancient and beautiful city. Once known as Constantinople, it has been at the centre of major empires including the Roman, Byzantine, Latin and Ottoman. This great city is inundated with rich culture and history, and with nearly 14 million inhabitants it is also one of the largest cities in the world.
But this thriving metropolis sits on the edge of one of the fastest moving faults in the world: the North Anatolian Fault. This is a system of large fractures within the Earth on which energy, from the motion of the tectonic plates, is stored and released in earthquakes.
The North Anatolian Fault is roughly 1300km long, running along the entire length of northern Turkey from the Aegean Sea in the west to Lake Van in the east. It slips such that central and southern Turkey are moving west relative to northern Turkey at speeds of 20-30mm a year. It is the most active and destructive earthquake-prone fault system in Turkey.
It has been known for a while now that earthquakes on the fault tend to follow a regular sequence. That is, an earthquake will often occur on the section of the fault adjacent to the last rupture. Starting with the 1939 magnitude 7.9 Erzincan earthquake and culminating in the 1999 magnitude 7.4 and 7.2 earthquakes, there have been 12 events with magnitudes greater than 6.4 that together have ruptured almost the entire length of the fault.
The map shows this westward progression of seismic activity. The 1999 Izmit (magnitude 7.4) and Duzce (magnitude 7.2) earthquakes killed about 18,000 people, mostly in the city of Izmit. These events occurred less than 100km east of Istanbul, leading some researchers to predict the next quake will strike Istanbul itself.
Seismologists calculate the chance of an earthquake greater than magnitude 7 occurring near Istanbul in the next 30 years at somewhere between 35 and 70 per cent. And with almost a million people moving to the metropolis every year it is no surprise that Istanbul is a major candidate for the so called ‘million-death quake.’
We need to improve our ability to forecast such quakes by creating realistic models of the fault’s behaviour, and to do this we need to know more about the fault itself.
The NERC-funded FaultLab project based at the University of Leeds is helping address these problems, with support from the University’s Climate and Geohazard Services group. The investigators use data from a multitude of sources including satellite radar and geological observations, as well as data from the densest network of seismic stations ever deployed across a fault.
The project scientists aim to use the seismic data to investigate the deep structure of the fault and to see if there are differences in the crust either side of the fracture. The geologists will be looking at an old fault zone to probe the microscopic structure of minerals inside these large fracture zones. Together, these observations will enable us to better understand what the fault is doing deep in the ground and how this has affected the crust adjacent to it. The geodesy group (earth observation scientists) will use satellite radar to make accurate maps of how the ground surface is moving and relate that to the amount of energy being stored on the fault. Finally, the modelling team will link these observations together to produce an accurate picture of the behaviour of the fault. These results can then feed into models to make a more realistic forecast of the hazard Istanbul faces.
A resilient city
Professor Nicholas Ambraseys, a leading expert in the field, famously said: ‘Earthquakes don’t kill people, buildings do.’
We technically don’t need to know when the earthquake will occur to save lives. Death and injury can be prevented through simple engineering works to reinforce vulnerable buildings and by ensuring new structures are built to earthquake-resilient standards. It’s estimated to cost only 10 per cent more to build a house that is earthquake resistant compared to one that isn’t.
The Turkish government has not been idle. The new Sabiha Gökçen International Airport terminal, which opened in October 2009, is designed to withstand shaking from a magnitude 8 earthquake and, importantly, keep working afterwards – this will be an important entry point for foreign aid after a disaster.
The Marmaray rail tunnel, opened in October 2013, runs beneath the Bosphorus Straits and links the European and Asian sides of the country. The rail tunnel was built to withstand a magnitude 9 earthquake.
In May 2012 a new Urban Transformation Law was passed, stating that all buildings that do not meet current earthquake hazard criteria will be demolished. This means nearly 6.5 million buildings throughout Turkey could be demolished over the next two decades, and will pave the way for more resilient cities.
Ambitions on this scale need strong governance and management, but they also need good science – to help the Turkish government prioritise its engineering projects and work on effective evacuation and mitigation plans. The results from the FaultLab project will help develop and refine their forecast models, so those plans can be put in action the moment there’s a sign that a deadly earthquake is imminent.
