Research into deadly 2016 Italian earthquakes could improve future seismic forecasts

The timing and size of three deadly earthquakes that struck Italy in 2016 may have been pre-determined, according to new research that could improve future earthquake forecasts.

A joint British-Italian team of geologists and seismologists have shown that the clustering of the three quakes might have been caused by the arrangement of a cross-cutting network of underground faults.

The findings show that although all three earthquakes occurred on the same major fault, several smaller faults prevented a single massive earthquake from occurring instead and also acted as pathways for naturally occurring fluids that triggered later earthquakes.

The cluster of three earthquakes, termed a “seismic sequence” by seismologists, each had magnitudes greater than six and killed more than 300 people in Italy’s Apennine mountains between 24 August and 30 October 2016.

Location of survey site at rupture across a road near Castelluccio, Italy. The rupture occurred during the third earthquake in the seismic sequence and gives researchers a record of the deformation. Credit: Laura Gregory, University of Leeds

Location of survey site at rupture across a road near Castelluccio, Italy. The rupture occurred during the third earthquake in the seismic sequence and gives researchers a record of the deformation.
Credit: Laura Gregory, University of Leeds

The research, led by Durham University, UK, comes ahead of the second anniversary of the start of the earthquake sequence.

The study is published in the journal Earth and Planetary Science Letters.

The researchers say the findings could have wider implications for the study of seismic hazards, enabling scientists to better understand potential earthquake sequences following a quake.

Dr Richard Walters, Assistant Professor in the Department of Earth Sciences, Durham University, said: “These results address a long-standing mystery in earthquake science — why a major fault system sometimes fails in a single large earthquake that ruptures its entire length, versus failing in multiple smaller earthquakes drawn-out over months or years.

“Our results imply that even though we couldn’t have predicted when the earthquake sequence would start, once it got going, both the size and timing of the major earthquakes may have been pre-determined by the arrangement of faults at depth.

“This is all information we could hypothetically know before the event, and therefore, this could be a hugely important avenue for improving future earthquake forecasts.”

Dr Walters and the team used satellite data to estimate which part of the fault failed in each earthquake, and compared this pattern with the location and timing of thousands of tiny aftershocks throughout the seismic sequence.

They found that intersections of small faults with the main fault system separated each of the three largest earthquakes, strongly suggesting these intersections stop the growth of each earthquake and prevent the faults failing in a single large event.

But in addition, the scientists also found that after the first earthquake, thousands of aftershocks crept northwards along these same fault intersections at a rate of around 100 metres per day, in a manner consistent with naturally occurring water and gas being pumped along the faults by the first earthquake on 24 August, 2016.

The second earthquake, on the 26 October, occurred exactly when these fluids reached its location, therefore controlling the relative timing of failure.

Dr Walters added: “It was a big surprise that these relatively small faults were having such a huge influence over the whole sequence.

“They stop the first earthquake in its tracks, and then they channel the fluids that start the sequence up again months later. No-one’s ever seen this before.”

Co-author Dr Laura Gregory, in the School of Earth and Environment, at the University of Leeds, UK, said it was important to understand whether or not a fault fails in a seismic sequence, and that the team’s results were only made possible by combining a varied array of different datasets.

Dr Gregory said: “A seismic sequence has vastly different implications for seismic hazard compared to a single large earthquake. If the faults in Italy in 2016 had failed together in one big event, the impact on the local population would have been much worse.

“This is the first time we’ve ever had this quality of modern data over one of these earthquake sequences, and bringing together a range of specialists was key for unpicking how the earthquakes related to one another.

“I was scrambling over the mountainside immediately after each earthquake with British and Italian colleagues, measuring the metre-high cliffs that had suddenly formed. Meanwhile, other members of our team were analysing data from seismometers stationed around the world, or were mapping the tiny bending of the ground around the faults using satellites orbiting the planet at 500 miles altitude.”

The research was partly supported by the UK’s Natural Environment Research Council, via an Urgency Grant, and through the Centre for the Observation and Modelling of Earthquakes, Volcanoes and Tectonics (COMET).

Study of material surrounding distant stars shows that Earth’s ingredients are pretty normal

The Earth’s building blocks seem to be built from ‘pretty normal’ ingredients, according to researchers working with the world’s most powerful telescopes. Scientists have measured the compositions of 18 different planetary systems from up to 456 light years away and compared them to ours, and found that many elements are present in similar proportions to those found on Earth.

This is amongst the largest examinations to measure the general composition of materials in other planetary systems, and begins to allow scientists to draw more general conclusions on how they are forged, and what this might mean for finding Earth-like bodies elsewhere.

“Most of the building blocks we have looked at in other planetary systems have a composition broadly similar to that of the Earth,” said researcher Dr Siyi Xu of the Gemini Observatory in Hawaii, who was presenting the work at the Goldschmidt conference in Boston.

The first planets orbiting other stars were only found in 1992 (this was orbiting a pulsar), since then scientists have been trying to understand whether some of these stars and planets are similar to our own solar system.

“It is difficult to examine these remote bodies directly. Because of the huge distances involved, their nearby star tends to drown out any electromagnetic signal, such as light or radio waves” said Siyi Xu. “So we needed to look at other methods.”

Because of this, the team decided to look at how the planetary building blocks affect signals from white dwarf stars. These are stars which have burnt off most of their hydrogen and helium, and shrunk to be very small and dense — it is anticipated that our Sun will become a white dwarf in around 5 billion years.

Dr Xu continued, “White dwarfs’ atmospheres are composed of either hydrogen or helium, which give out a pretty clear and clean spectroscopic signal. However, as the star cools, it begins to pull in material from the planets, asteroids, comets and so on which had been orbiting it, with some forming a dust disk, a little like the rings of Saturn. As this material approaches the star, it changes how we see the star. This change is measurable because it influences the star’s spectroscopic signal, and allows us to identify the type and even the quantity of material surrounding the white dwarf. These measurements can be extremely sensitive, allowing bodies as small as an asteroid to be detected.”

The team took measurements using spectrographs on the Keck telescope in Hawaii, the world’s largest optical and infrared telescope, and on the Hubble Space Telescope.

Siyi Xu continued, “In this study, we have focused on the sample of white dwarfs with dust disks. We have been able to measure calcium, magnesium, and silicon content in most of these stars, and a few more elements in some stars. We may also have found water in one of the systems, but we have not yet quantified it: it’s likely that there will be a lot of water in some of these worlds. For example, we’ve previously identified one star system, 170 light years away in the constellation Boötes, which was rich in carbon, nitrogen and water, giving a composition similar to that of Halley’s Comet. In general though, their composition looks very similar to bulk Earth.

This would mean that the chemical elements, the building blocks of earth are common in other planetary systems. From what we can see, in terms of the presence and proportion of these elements, we’re normal, pretty normal. And that means that we can probably expect to find Earth-like planets elsewhere in our Galaxy.”

Dr Xu continued “This work is still on-going and the recent data release from the Gaia satellite, which so far has characterized 1.7 billion stars, has revolutionized the field. This means we will understand the white dwarfs a lot better. We hope to determine the chemical compositions of extrasolar planetary material to a much higher precision”

Professor Sara Seager, Professor of Planetary Science at Massachusetts Institute of Technology, is also the deputy science director of the recently-launched TESS (Transiting Exoplanet Survey Satellite) mission, which will search for exoplanets. She said:

“It’s astonishing to me that the best way to study exoplanet interiors is by planets ripped apart and absorbed by their white dwarf host star. It is great to see progress in this research area and to have solid evidence that planets with Earth-like compositions are common — fueling our confidence that an Earth-like planet around a very nearby normal star is out there waiting to be found.”

Citation: Goldschmidt Conference. “Study of material surrounding distant stars shows Earth’s ingredients ‘pretty normal’.” ScienceDaily. ScienceDaily, 15 August 2018. <www.sciencedaily.com/releases/2018/08/180815190530.htm>.

New Antarctic rift data has implications for volcanic evolution

New data revealing two tectonic plates fused to form a single Antarctic Plate 15 million years later than originally predicted and this extra motion has major implications for understanding of the tectono-volcanic activity surrounding the Pacific Ocean, from the Alpine mountains in New Zealand to the California geological setting, according to research from Ben-Gurion University of the Negev (BGU).

In a study published in Nature Communications, Dr. Roi Granot of BGU’s Department of Geological and Environmental Sciences, and Dr. Jérôme Dyment from the Institut de Physique du Globe de Paris, France, present marine magnetic data collected near the northern edge of the West Antarctic rift system that shows motion between East and West Antarctica, which was assumed to have ended abruptly 26 million years ago, actually continued for another 15 million years.

“Since Antarctica tectonically connects the Pacific Plate to the rest of the world, these results have important ramifications for understanding the tectonic evolution around the Pacific Ocean — the rise of New Zealand’s Alpine Mountains, motions along the San Andreas Fault in California, and more,” says Dr. Granot.

Over 200 million years ago, a rift bisected Antarctica. The motion between East Antarctic and West Antarctic Plates accommodated along the length of this rift created one of the longest mountain ranges in the world (the Transantarctic Mountains). It also caused the eruption of hundreds of volcanoes, mostly under the ice sheets, and shaped the sub-ice topography. These motions dictated, and still dictate, the heat flow rate that the crust releases under the ice and is one of the factors controlling the rate by which the glaciers are advancing toward the surrounding southern ocean.

GPS data and a lack of seismic activity suggest that the rift in Antarctica is no longer tectonically active. According to the researchers, one of the key unanswered question was: How did the plates drift relative to each other over the last 26 million years and when did the rift stop being active?

New marine geophysical data recorded during two excursions on a French icebreaker enabled Drs. Roi Granot and Jérôme Dyment to date the ocean floor and calculate the relative motion between the Antarctic Plates and the Australian Plate.

“Antarctica forms an important link in the global plate tectonic circuits which enable to calculate the motion along different plate boundaries. Understanding past plate motions between East and West Antarctica therefore affects our ability to accurately predict the kinematic evolutions of other plate boundaries,” says Dr. Granot.

Citation: American Associates, Ben-Gurion University of the Negev. “New Antarctic rift data has implications for volcanic evolution.” ScienceDaily. ScienceDaily, 21 August 2018. <www.sciencedaily.com/releases/2018/08/180821094150.htm>.

Meteorite bombardment likely to have created the Earth’s oldest rocks

Scientists have found that 4.02-billion-year-old silica-rich felsic rocks from the Acasta River, Canada — the oldest rock formation known on Earth — probably formed at high temperatures and at a surprisingly shallow depth of the planet’s nascent crust. The high temperatures needed to melt the shallow crust were likely caused by a meteorite bombardment around half a billion years after the planet formed. This melted the iron-rich crust and formed the granites we see today. These results are presented for the first time at the Goldschmidt conference in Boston (14 August), following publication in the peer-reviewed journal Nature Geoscience.

Oldest rock on Earth: Acasta River gneiss (stock image). Credit: © Xenomanes / Fotolia

Oldest rock on Earth: Acasta River gneiss (stock image).
Credit: © Xenomanes / Fotolia

The felsic rocks (rocks rich in silica/quartz) found at the Acasta River in Canada, are the Earth’s oldest rocks, although there are older mineral crystals*. Scientists have long known that the Acasta rocks are different to the majority of felsic rocks we see today, such as the granites widely used as a building or decorative material. Now a group of scientists from Australia and China have modelled the formation of the oldest Acasta felsic rocks and found that they could only have been formed at low pressures and very high temperatures.

Scientists believe that the primitive crust largely comprised dark, silica-poor mafic rocks, so there has been a question over how the Acasta River felsic rocks could have formed.

“Our modelling shows that the Acasta River rocks derived from the melting of pre-existing iron-rich basaltic rock, which formed the uppermost layers of crust on the primitive Earth,” said team leader Tim Johnson, from Curtin University, Perth.

“We used phase equilibria and trace element modelling to show that the Acasta River rocks were produced by partial melting of the original mafic rocks at very low pressures. It would have needed something special to produce the 900°C temperatures needed to generate these early felsic rocks at such low pressures, and that probably means a drastic event, most likely the intense heating caused by meteorite bombardment.

We estimate that rocks within the uppermost 3km of mafic crust would have been melted in producing the rocks we see today. We think that these ancient felsic rocks would have been very common, but the passage of 4 billion years, and the development of plate tectonics, means that almost nothing remains.

We believe that these rocks may be the only surviving remnants of a barrage of extraterrestial impacts which characterized the first 600 million years of Earth History.”

The Acasta River is part of the Slave Craton formation in Northern Canada, north of Yellowknife and the Great Slave Lake. The area is the homeland of the Tlicho people, which led to the geologists who discovered the rocks giving them the name “Idiwhaa,” derived from the Tlicho word for ancient.

Commenting, Dr Balz Kamber (Trinity College Dublin) said: “The idea of making felsic melts by large or giant impacts seems plausible considering the high-energy nature of these events and the pockmarked ancient surfaces of other inner Solar System planets and moons. However, the implied pressure-temperature regime might also permit melting of shallow crust below a super-heated impact melt sea. In other words, an indirect consequence of the impact itself.”

* Rocks from Jack Hills in Australia contain zircon crystals from up to 4.4 billion years ago, embedded in younger rocks.

Source: www.sciencedaily.com

Citation: Goldschmidt Conference. “Meteorite bombardment likely to have created the Earth’s oldest rocks.” ScienceDaily. ScienceDaily, 14 August 2018. <www.sciencedaily.com/releases/2018/08/180813113334.htm>.

99-million-year-old beetle trapped in amber served as pollinator to evergreen cycads

Flowering plants are well known for their special relationship to the insects and other animals that serve as their pollinators. But, before the rise of angiosperms, another group of unusual evergreen gymnosperms, known as cycads, may have been the first insect-pollinated plants. Now, researchers reporting in the journal Current Biology on August 16 have uncovered the earliest definitive fossil evidence of that intimate relationship between cycads and insects.

This image shows a dorsal view of the mid-Cretaceous beetle Cretoparacucujus cycadophilus, including the mandibular cavities it likely used for pollination. Credit: Chenyang Cai

This image shows a dorsal view of the mid-Cretaceous beetle Cretoparacucujus cycadophilus, including the mandibular cavities it likely used for pollination.
Credit: Chenyang Cai

The discovery came in the form of an ancient boganiid beetle preserved in Burmese amber for an estimated 99 million years along with grains of cycad pollen. The beetle also shows special adaptations, including mandibular patches, for the transport of cycad pollen.

“Boganiid beetles have been ancient pollinators for cycads since the Age of Cycads and Dinosaurs,” says Chenyang Cai, now a research fellow at the University of Bristol. “Our find indicates a probable ancient origin of beetle pollination of cycads at least in the Early Jurassic, long before angiosperm dominance and the radiation of flowering-plant pollinators, such as bees, later in the Cretaceous.”

When Cai’s supervisor Diying Huang at the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, first showed him the beetle trapped in amber, he was immediately intrigued. He recognized that its large mandibles with bristly cavities might suggest the beetle was a pollinator of cycads.

After cutting, trimming, and polishing the specimen to get a better look under a microscope, Cai’s excitement only grew. The beetle carried several clumps of tiny pollen grains. Cai consulted Liqin Li, an expert in ancient pollen at the Chinese Academy of Sciences, who confirmed that the pollen grains belonged to a cycad.

The researchers also conducted an extensive phylogenetic analysis to explore the beetle’s family tree. Their analysis indicates the fossilized beetle belonged to a sister group to the extant Australian Paracucujus, which pollinate the relic cycad Macrozamia riedlei. The finding, along with the current disjunct distribution of related beetle-herbivore and cycad-host pairs in South Africa and Australia, support an ancient origin of beetle pollination of cycads, the researchers say.

Cai notes that the findings together with the distribution of modern boganiid beetles lead him to suspect that similar beetle pollinators of cycads are yet to be found. He’s been looking for them for the last five years. The challenge, he says, is that older Jurassic beetles are generally found as compression fossils not trapped in amber.

Source: www.sciendaily.com

Citation: Cell Press. “99-million-year-old beetle trapped in amber served as pollinator to evergreen cycads.” ScienceDaily. ScienceDaily, 16 August 2018. <www.sciencedaily.com/releases/2018/08/180816143240.htm>.

 

Prehistoric peopling in southeast Asia: Genomics of Jomon and other ancient skeletons

Uncovering the expansion processes of human habitats in the past is of great importance for understanding the origins and establishment of present-day populations and the acquisition of genetic characteristics of individuals as well as for investigating mechanisms of resistance against diseases and pathogens. Previous genetic/genomic studies aimed to uncover the expansion processes using present-day human genomes of different individuals and locations. However, it is not always possible to elucidate the expansion processes based on the genomic similarity of present-day populations due to the possibility of migrations of populations between regions in various periods. It is therefore impossible to uncover the precise expansion processes of populations in the past without knowledge of the genomic information existing in a designated region and period. Thus, expansion processes hypothesized so far were nothing but speculations based on assumptions about present-day genomes.

Model for migration routes into Southeast Asia uncovered by genomic data of prehistoric skeletons. Credit: Kanazawa University

Model for migration routes into Southeast Asia uncovered by genomic data of prehistoric skeletons.
Credit: Kanazawa University

Recent developments of DNA analysis technology have made it possible to obtain whole genome information from ultratrace amounts of DNA; we are now in an era where whole genome information can be obtained directly from ancient human skeletons discovered at archaeological sites. There remain, however, technical problems for obtaining whole genome information of ancient human skeletons. In particular, there are two main problems: first, genomic analyses*1) of poorly-preserved ancient remains in hot and humid regions of the world have up until now failed. Secondly, there is the risk of contamination of present-day human DNA in the DNA samples of ultratrace amounts from prehistoric remains. To evaluate objectively the possibility of such contamination, several different research groups must cross-check*2) one another in order to achieve exact genome sequencing; in other words, establishment of a collaborative research system is a prerequisite for attaining the highest level of scientific authenticity.

In order to cope with these problems, the present international research team, led by researchers from the University of Copenhagen with the participation of three researchers from Kanazawa University has established technologies to efficiently extract human DNA from skeletons discovered at prehistoric remains even under very poor conditions for DNA preservation. At the same time, an international system of research collaboration has been established for objectively evaluating the effects of contamination by present-day human DNA. Thanks to these efforts, the team has uncovered the expansion processes of human habitats and genetic interactions in hot and wet Southeast Asia, which was not possible previously with conventional technologies and research systems.

Worthy of special mention, the present study has been successful in determining the “whole genome” sequence of an individual with typical Jomon culture, while previous studies were only able to show a very limited “partial genome” sequence of two Jomon individuals. Thus, the present study is the first successful example to show the possibility of whole genome sequencing of prehistoric individuals in regions like Japan where preservation conditions are quite poor, possibly leading to further major progress in prehistoric genome studies.

In the present study, the international research team succeeded in extracting and sequencing DNA from 25 ancient individuals’ skeletons from Southeast Asian remains, where the condition of DNA preservation is very poor, and from one Japanese Jomon female skeleton. Upon comparison of the genomic data of ancient human skeletons with those of present-day human skeletons, it has become clear that those prehistoric populations in Southeast Asia can be classified into six groups.

Group 1 contains Hoabinhians from Pha Faen, Laos, hunter-gatherers (~8000 years ago), and prehistoric populations discovered from Gua Cha, Malaysia (~4000 years ago), being genetically close to present-day Önge and Jarawa from the Andaman Islands and Jehai from the Peninsular Malaysia. To our surprise, group 1 has higher genetic affinities with Ikawazu*3) Jomon individual (Tahara, Aichi), a female adult*4), than other present-day Southeast Asians. In addition, the Ikawazu Jomon genome*5) is best modelled contributing genetically present-day Japanese.

On the other hand, Groups 2-6 consist of ancient skeletons from the Neolithic Age, when farming started, until ~500 years ago. It is now found that they are genetically much different from Hoabinhians, each group having histories of migration and genetic interaction, i.e., inter-population mixture. Group 2 is found to be genetically close to the present-day Austroasiatic language-speaking groups such as Mlabri, but to have few genetic components common with the present-day East Asian populations. Group 3 is found to be genetically close to Kradai, Thailand, in the present-day Southeast Asian populations and to the Austronesian language-speaking groups. Group 4 is found to be genetically close to the present-day populations in South China. Group 5 is genetically close to the present-day populations in the western part of Indonesia. Group 6 is most closely related to present day Austronesian populations, with one individual showing slightly elevated Denisovan ancestry, an archaic hominin which is classified as a sister group of Neanderthals.

As above, Neolithic Southeast Asians are found to have been partially genetically influenced by ethnic groups in South China and to have had a genetic connection with populations in Taiwan; Neolithic Southeast Asians are found not to have been indigenous hunter-gatherers passively accepting farming but to have accepted farming gradually in the process of migrations of populations between the continent and islands. Conventional archaeology proposed the two-layer hypothesis that, in those periods, a large population with farming culture with rice and millet migrated into Southeast Asia and that they replaced the indigenous population. Additionally, the present study indicates that the genetic influence from South China with rice farming was only partial and that the migrating population did not replace the indigenous population completely. The present analysis shows that there were at least four big migration waves; migrations of Southeast Asians should be investigated with a new “complex model” framework.

The present study successfully elucidates for the first time the expansion/migration of prehistoric populations by genome analysis of skeletons discovered in Southeast Asia; conventionally, it was thought that such population expansion/migration could only be investigated using archaeological artifacts. An important outcome of the present study is that the same or analogous analyses could be applied to various regions to evaluate the history of population expansion/migration in much more detail and in a more scientific manner.

The genomic data obtained from ancient skeletons in Southeast Asia and from a Ikawazu Jomon individual provides an important basis for investigations on the origins of populations in wider East Asia. The whole genome information of a Jomon individual will be useful for direct comparison of genomic similarity with ancient East Asians of the corresponding period to Jomon in present-day Korea, China, Russia and others in the vicinity of the Japanese archipelago. More comparative studies are in progress on populations in wider areas. Note that the whole genome sequence obtained in this study for a Jomon individual corresponds to the Draft Genome Sequence in the Human Genome Project for the present-day humans. We aim at Complete Genome Sequence with higher accuracy.

This study is an interdisciplinary undertaking combining anthropology and archaeology in a close collaboration, allowing us to establish ourselves at the starting point for research on the origin of Jomon and its diversity. By more genome analyses of more Jomon skeletons from different Jomon sites, genetic diversity of Jomon populations will be explored over the Japanese archipelago. It is expected through such studies that various interactions among Jomon groups should be revealed together with migrations of archaeological artifacts such as potteries and stone tools as well as migrations of populations. Based on the outcome of the present study, novel anthropological and archaeological approaches would be further developed.

Source: www.sciencedaily.com

Citation: Kanazawa University. “Prehistoric peopling in southeast Asia: Genomics of Jomon and other ancient skeletons.” ScienceDaily. ScienceDaily, 9 August 2018. <www.sciencedaily.com/releases/2018/08/180809093427.htm>.

WFS News: Nano-Scale Spheroids and Fossils from the Ediacaran Doushantuo Formation in China

@WFS,World Fossil Society,Riffin T Sajeev,Russel T Sajeev

Exceptionally preserved nano-scale spheroids derived from microbial processes and nano-scale fossils have been discovered from the black shales of the Jijiawan section of the Ediacaran Doushantuo Formation in the Yangtze Gorge area of Hubei Province, southern China. The numerous soccer ball-like spheroids are pyritized. Their morphology and abundant preservation may suggest that they could possibly be related to larger spheroids, regardless of the tremendous dimensional gap found in the phosphorite and cherts of the Doushantuo Formation, including those recognized as ‘embryos’. The colony-like spheroids preserved in situ and obtained by acid maceration are compared with known Neoproterozoic microfossils—Bavlinella faveolata (or Sphaerocongregus variabilis). Additionally, nano-scale fossil bodies, characterized by morphological features comparable to living cyanobacteria, fungi and possible unicellular heterotrophic protists were observed in different minor laminae of the black shale samples. This study aims to reveal the aspects of nano-scale biota preserved in the black shale of the Ediacaran Doushantuo Formation, and highlight the taphonomy of microorganisms during the key transition from the anoxic deeper oceans to the oxygenated oceans of the early Ediacaran interval.

Nano-scale spheroids found in the black shales of the Ediacaran Doushantuo Formation in the Jijiawan section, Hubei, China.A–E, I, L, M Soccer ball-like spheroids with probable hollow interior and polygonal cracks, preserved in situ (except specimen M, which was obtained by acid maceration); specimen I displays tuberculiform ornamentation on its surface. F, G colony-like spheroids, which were obtained from organic residues of acid maceration and are compared with known fossils — Bavlinella faveolata. G is a magnification of part of F to show ductile walls (arrow) and possible fine ornamentation on the surface. H, J, K single spheroids with hollow cavities, H was obtained from organic residues of acid maceration, J and K are preserved in situ.

Nano-scale spheroids found in the black shales of the Ediacaran Doushantuo Formation in the Jijiawan section, Hubei, China.A–E, I, L, M Soccer ball-like spheroids with probable hollow interior and polygonal cracks, preserved in situ (except specimen M, which was obtained by acid maceration); specimen I displays tuberculiform ornamentation on its surface. F, G colony-like spheroids, which were obtained from organic residues of acid maceration and are compared with known fossils — Bavlinella faveolata. G is a magnification of part of F to show ductile walls (arrow) and possible fine ornamentation on the surface. H, J, K single spheroids with hollow cavities, H was obtained from organic residues of acid maceration, J and K are preserved in situ.

Morphological features similar to those of modern cyanobacteria characterize the preservation of nano-scale fossils [45]. Possible fungal spore and unicellular heterotrophic protists may imply that a diverse nano-scale biota, including prokaryotes and heterotrophic eukaryotes, existed in the early Ediacaran anoxic deeper ocean. Although most of the nano-scale spheroids and fossils obtained from the black shale of the lower part of the Doushantuo Formation were strongly carbonized and mineralized, these findings further reveal aspects of life during this key period of transition from anoxic deeper oceans to oxygenated oceans.

Consequently, the investigation of the biological link that may have existed between such nano-scale microbes and much larger microfossils, particularly acanthmorphic acritarchs, animal embryos and other possible animal remains, during the earlier Ediacaran period is significant. Mineralogically, the studied black shales contain abundant pyrite and gypsum, which alternate within thin laminae. This may signify that redox conditions were fluctuating and a semi-enclosed marine lagoonal palaeoenvironment could have been suitable for the sedimentation and diagenesis of the studied Doushantuo black shales. The fact that many specimens of colony-like spheroids are comparable in their nano-scale biotic associations to Bavlinellafaveolata and other cyanobacteria may suggest that an extraordinarily stressed environment existed during this key geological interval.

Tenger Borjigin1Leiming Yin2*Lizeng Bian3Xunlai Yuan2Chuanming Zhou2Fanwei Meng2Xiaomin Xie1Fang Bao1
1 Key Laboratory of Petroleum Accumulation Mechanisms, Wuxi Research Institute of Petroleum Geology, SINOPEC, Wuxi 214151, Jiangsu, China
2 State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, Jiangsu, China
3 School of Earth Sciences and Engineering, Nanjing University, Nanjing 210008, Jiangsu, China

@WFS,World Fossil Society,Riffin T Sajeev,Russel T Sajeev

Scientists solve the mystery behind the origin of skeletons!!!

Scientists at The University of Manchester and the University of Bristol have used powerful X-rays to peer inside the skeletons of some of our oldest vertebrate relatives, solving a 160-year-old mystery about the origin of our skeletons.

Living vertebrates have skeletons built from four different tissue types: bone and cartilage (the main tissues that human skeletons are made from), and dentine and enamel (the tissues from which our teeth are constructed). These tissues are unique because they become mineralised as they develop, giving the skeleton strength and rigidity.

Evidence for the early evolution of our skeletons can be found in a group of fossil fishes called heterostracans, which lived over 400 million years ago. These fishes include some of the oldest vertebrates with a mineralised skeleton that have ever been discovered. Exactly what tissue heterostracan skeletons were made from has long puzzled scientists.

Now a team of researchers from the University of Manchester, the University of Bristol and the Paul Scherrer Institute in Switzerland have taken a detailed look inside heterostracan skeletons using Synchrotron Tomography: a special type of CT scanning using very high energy X-rays produced by a particle accelerator. Using this technique, the team have identified this mystery tissue.

Lead researcher Dr Joseph Keating, from Manchester’s School of Earth of Environmental Scientists, explained: “Heterostracan skeletons are made of a really strange tissue called ‘aspidin’. It is crisscrossed by tiny tubes and does not closely resemble any of the tissues found in vertebrates today. For a 160 years, scientists have wondered if aspidin is a transitional stage in the evolution of mineralised tissues.”

A fossil heterostracan, Errivaspis waynensis, from the early Devonian (approximately 419 million years ago) of Herefordshire, UK. Credit: Image from Keating et al. 2018

A fossil heterostracan, Errivaspis waynensis, from the early Devonian (approximately 419 million years ago) of Herefordshire, UK.
Credit: Image from Keating et al. 2018

The results of this study, published in Nature Ecology and Evolution, show that the tiny tubes are voids that originally housed fibre-bundles of collagen, a type of protein found in your skin and bones.

These findings enabled Dr Keating to rule out all but one hypothesis for the tissue’s identity: aspidin is the earliest evidence of bone in the fossil record.

Co-author, Professor Phil Donoghue from the University of Bristol concludes: “These findings change our view on the evolution of the skeleton. Aspidin was once thought to be the precursor of vertebrate mineralised tissues. We show that it is, in fact, a type of bone, and that all these tissues must have evolved millions of years earlier.”

Citation: University of Manchester. “160-year-old mystery about the origin of skeletons solved.” ScienceDaily. ScienceDaily, 31 July 2018. <www.sciencedaily.com/releases/2018/07/180731104259.htm>.

Source: www.sciencedaily.com

Sound waves reveal enormous diamond cache deep in Earth’s interior

There may be more than a quadrillion tons of diamond hidden in the Earth’s interior, according to a new study from MIT and other universities. But the new results are unlikely to set off a diamond rush. The scientists estimate the precious minerals are buried more than 100 miles below the surface, far deeper than any drilling expedition has ever reached.

The ultradeep cache may be scattered within cratonic roots — the oldest and most immovable sections of rock that lie beneath the center of most continental tectonic plates. Shaped like inverted mountains, cratons can stretch as deep as 200 miles through the Earth’s crust and into its mantle; geologists refer to their deepest sections as “roots.”

In the new study, scientists estimate that cratonic roots may contain 1 to 2 percent diamond. Considering the total volume of cratonic roots in the Earth, the team figures that about a quadrillion (1016) tons of diamond are scattered within these ancient rocks, 90 to 150 miles below the surface.

There may be more than a quadrillion tons of diamond hidden in the Earth's interior. Credit: © KristijanZontar / Fotolia

There may be more than a quadrillion tons of diamond hidden in the Earth’s interior.
Credit: © KristijanZontar / Fotolia

“This shows that diamond is not perhaps this exotic mineral, but on the [geological] scale of things, it’s relatively common,” says Ulrich Faul, a research scientist in MIT’s Department of Earth, Atmospheric, and Planetary Sciences. “We can’t get at them, but still, there is much more diamond there than we have ever thought before.”

Faul’s co-authors include scientists from the University of California at Santa Barbara, the Institut de Physique du Globe de Paris, the University of California at Berkeley, Ecole Polytechnique, the Carnegie Institution of Washington, Harvard University, the University of Science and Technology of China, the University of Bayreuth, the University of Melbourne, and University College London.

A sound glitch

Faul and his colleagues came to their conclusion after puzzling over an anomaly in seismic data. For the past few decades, agencies such as the United States Geological Survey have kept global records of seismic activity — essentially, sound waves traveling through the Earth that are triggered by earthquakes, tsunamis, explosions, and other ground-shaking sources. Seismic receivers around the world pick up sound waves from such sources, at various speeds and intensities, which seismologists can use to determine where, for example, an earthquake originated.

Scientists can also use this seismic data to construct an image of what the Earth’s interior might look like. Sound waves move at various speeds through the Earth, depending on the temperature, density, and composition of the rocks through which they travel. Scientists have used this relationship between seismic velocity and rock composition to estimate the types of rocks that make up the Earth’s crust and parts of the upper mantle, also known as the lithosphere.

However, in using seismic data to map the Earth’s interior, scientists have been unable to explain a curious anomaly: Sound waves tend to speed up significantly when passing through the roots of ancient cratons. Cratons are known to be colder and less dense than the surrounding mantle, which would in turn yield slightly faster sound waves, but not quite as fast as what has been measured.

“The velocities that are measured are faster than what we think we can reproduce with reasonable assumptions about what is there,” Faul says. “Then we have to say, ‘There is a problem.’ That’s how this project started.”

Diamonds in the deep

The team aimed to identify the composition of cratonic roots that might explain the spikes in seismic speeds. To do this, seismologists on the team first used seismic data from the USGS and other sources to generate a three-dimensional model of the velocities of seismic waves traveling through the Earth’s major cratons.

Next, Faul and others, who in the past have measured sound speeds through many different types of minerals in the laboratory, used this knowledge to assemble virtual rocks, made from various combinations of minerals. Then the team calculated how fast sound waves would travel through each virtual rock, and found only one type of rock that produced the same velocities as what the seismologists measured: one that contains 1 to 2 percent diamond, in addition to peridotite (the predominant rock type of the Earth’s upper mantle) and minor amounts of eclogite (representing subducted oceanic crust). This scenario represents at least 1,000 times more diamond than people had previously expected.

“Diamond in many ways is special,” Faul says. “One of its special properties is, the sound velocity in diamond is more than twice as fast as in the dominant mineral in upper mantle rocks, olivine.”

The researchers found that a rock composition of 1 to 2 percent diamond would be just enough to produce the higher sound velocities that the seismologists measured. This small fraction of diamond would also not change the overall density of a craton, which is naturally less dense than the surrounding mantle.

“They are like pieces of wood, floating on water,” Faul says. “Cratons are a tiny bit less dense than their surroundings, so they don’t get subducted back into the Earth but stay floating on the surface. This is how they preserve the oldest rocks. So we found that you just need 1 to 2 percent diamond for cratons to be stable and not sink.”

In a way, Faul says cratonic roots made partly of diamond makes sense. Diamonds are forged in the high-pressure, high-temperature environment of the deep Earth and only make it close to the surface through volcanic eruptions that occur every few tens of millions of years. These eruptions carve out geologic “pipes” made of a type of rock called kimberlite (named after the town of Kimberley, South Africa, where the first diamonds in this type of rock were found). Diamond, along with magma from deep in the Earth, can spew out through kimberlite pipes, onto the surface of the Earth.

For the most part, kimberlite pipes have been found at the edges of cratonic roots, such as in certain parts of Canada, Siberia, Australia, and South Africa. It would make sense, then, that cratonic roots should contain some diamond in their makeup.

“It’s circumstantial evidence, but we’ve pieced it all together,” Faul says. “We went through all the different possibilities, from every angle, and this is the only one that’s left as a reasonable explanation.”

This research was supported, in part, by the National Science Foundation.

Citation: Massachusetts Institute of Technology. “Sound waves reveal enormous diamond cache deep in Earth’s interior: Study finds one to two percent of Earth’s oldest mantle rocks are made from diamond.” ScienceDaily. ScienceDaily, 16 July 2018. <www.sciencedaily.com/releases/2018/07/180716114538.htm>.

Source: www.sciencedaily.com

Glaciers in East Antarctica also ‘imperiled’ by climate change

Source:University of California – Irvine

A team of scientists from the University of California, Irvine has found evidence of significant mass loss in East Antarctica’s Totten and Moscow University glaciers, which, if they fully collapsed, could add 5 meters (16.4 feet) to the global sea level.

In a paper published this week in the American Geophysical Union journal Geophysical Research Letters, the glaciologists estimate that between April 2002 and September 2016, the two glaciers lost about 18.5 billion tons of ice per year — equivalent to 0.7 millimeters (0.03 inches) of global sea level rise over the analyzed time period.

UCI’s researchers discovered this by applying a locally optimized technique to data from NASA’s Gravity Recovery & Climate Experiment satellite mission, combined with mass balance approximations from regional atmospheric climate models and ice discharge measurements by NASA’s Operation IceBridge and Measures projects.

“For this research, we used an improved methodology with GRACE data to retrieve the mass loss in an area undergoing rapid change,” said lead author Yara Mohajerani, a graduate student in UCI’s Department of Earth System Science. “By overlaying these data with independent measurements, we improve our confidence in the results and the conclusion that Totten and Moscow University are imperiled.”

Making up roughly two-thirds of the Antarctic continent, East Antarctica has been viewed by polar researchers as less threatened by climate change than the volatile ice sheets in West Antarctica and the Antarctic Peninsula.

“Both of these glaciers are vulnerable to the intrusion of warm ocean water and hold considerable potential for sea level rise,” said co-author Eric Rignot, Donald Bren Professor and chair of Earth system science at UCI. “This work highlights that East Antarctic glaciers are as important to our future as those in the continent’s western regions.”

According to co-author Isabella Velicogna, professor of Earth system science, it’s challenging to study the Totten and Moscow University glaciers because the signal of change is much weaker than that of their counterparts in the west.

“In this remote part of the world, the data from GRACE and other satellite missions are critical for us to understand the glacier evolution,” she said.

Citation: University of California – Irvine. “Glaciers in East Antarctica also ‘imperiled’ by climate change: Usually seen as less vulnerable, they carry the potential to add 16 feet to global sea level.” ScienceDaily. ScienceDaily, 26 July 2018. <www.sciencedaily.com/releases/2018/07/180726161009.htm>.