Sunday, 23 October 2016

Magnitude 6.6 Earthquake in Tottori Prefecture, Japan.

The Japan Meteorological Agency recorded a Magnitude 6.6 Earthquake at a depth of about 10 km, about in central Tottori Prefecture on Honshū Island, slightly after 2.05 pm Japan Standard Time (slightly after 5.05 am GMT) on Friday 21 October 2016. Seven people have reportedly been injured following the event, one of whom is described as being in a serious condition, with two house collapses and damage to several other buildings also reported. About 40 000 were left without power following the event, and train services were suspended until the lines could be confirmed to be safe.  people have reported feeling it across much of southern Honshū, as well as on the neighbouring islands of Shikoku and Kyūshū.

Damage to the facade of a building following the 21 October 2016 Tottori Earthquake. AP.

Japan has a complex tectonic environment with four plates underlying parts of the Islands; in addition to the Pacific in the east and the Othorsk in the North, there are the Philippine Plate to the south and the Eurasian Plate to the West. The southwestern arm of Honshū Island lies at the northeast end of the Ryukyu Island Arc, which sits on top of the boundary between the Eurasian and Philippine Plates. The Philippine Plate is being subducted beneath the Eurasian Plate, along the Ryukyo Trench, to the Southeast of the Islands. This is not a smooth process, with the two plates continuously sticking together then breaking apart as the pressure builds up, leading to frequent Earthquakes in the region.

  The movement of the Pacific and Philippine Plates beneath eastern Honshu. Laurent Jolivet/Institut des Sciences de la Terre d'Orléans/Sciences de la Terre et de l'Environnement.

Witness accounts of Earthquakes can help geologists to understand these events, and the structures that cause them. The international non-profit organisation Earthquake Report is interested in hearing from people who may have felt this event; if you felt this quake then you can report it to Earthquake Report here.

 The approximate location of the 21 October 2016 Tottori Earthquake. Google.

See also... on Mount Aso, Kyūshū Island, Japan.                                                           The Japan Meteorological Agency has reported a major eruption on Aso (or Asosan) a volcanic caldera on central Kyūshū Island, Japan. The volcano erupted early on the morning of Saturday 6 October 2016... 4.2 Earthquake in Chiba Prefecture, Japan.                                                    The Japan Meteorological Agency recorded a Magnitude 4.2 Earthquake at a depth of about 30 km, about 6 km off the coast of the Chiba Peninsula on Honshū Island, at about 1.10 am on Wednesday 3 August 2016 Japan Standard Time (about 4.10 pm... 4.5 Earthquake in Kumamoto Prefecture, Japan.                                         The Japan Meteorological Agency recorded a Magnitude 4.5 Earthquake at a depth of about...
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Thursday, 20 October 2016

Brachiopods from the Late Cretaceous of South Island, New Zealand.

Brachiopods are Lophophorate animals related to Bryozoans and Phoranid Worms. They are superficially similar to Bivalve Molluscs, with a filter feeding animal living between two opposed shells, but their internal structure is quite different with a lophophore (net-like organ) being extruded to capture planktonic prey rather than the siphon of Bivalves which lets them pump in water and strain it for food. This, along with a different muscle structure used to seal the shell whch makes Brachiopods more vulnerable to predators such as Starfish, has led to the Brachiopods being less ecologically successful than the Bivalves in most environments, so that while Brachiopods dominated many Palaeozoic benthic ecosystems and are still extant today, they were progressively replaced in many environments by their Mollusc rivals during the Mesozoic, and by the end of the Cretaceous were uncommon members of invertebrate communities.

In a paper published in the Records of the Canterbury Museum on 29 September 2016, Norton Hiller of the Department of Geological Sciences at the University of Canterbury and the Canterbury Museum, describes a new species of Brachiopod from an exposure of the Mead Hill Formation on the foreshore at Kaikoura in North Canterbury on South Island, New Zealand. The fossils were discovered during a field trip by the Geological Society of New Zealand in 2005, made to make that organizations 50th anniversary, and were part of the first collection of macro-invertebrate fossils collected from the Mead Hill Formation, a collection that also included Sponges, Echinoid spines, and a possible Belemnite.

The new species is named Gowanella capralis, where 'Gowanella' refers to the Gowan Hill Farm, on whose land the specimens were found, and 'capralis' is a Latin word for a marsh, implying land fit only for the grazing of Goats, a reference to the marshy gully where the specimens were found. The species is described from six complete shells, two lose dorsal valves and two broken ventral valves. The shells are ventribiconvex, which is to say each half of the shell is convex, with the two halves separated by a raised median line (a common bodyplan in Brachiopods) and roughly hexagonal in outline, with a short beak and short robust teeth on the ventral valve.

Gowanella capralis. (A−D) First specimen, complete shell in dorsal (A), ventral (B), anterior (C), and lateral (D) views. (E) Second specimen, juvenile complete shell in dorsal view. (F−I) Third specimen, complete shell in dorsal (F), ventral (G), lateral (H), and anterior (I) views. (J−M) Fourth specimen, complete shell in dorsal (J), anterior (K), lateral (L), and ventral (M) views. (N) Fifth specimen, dorsal valve in interior view. (O) Sixth specimen, dorsal valve in interior view. (P-R) Seventh specimen, complete shell in dorsal (P), lateral (Q), and anterior (R) views. Hiller (2016).

Hiller also records a second type of Brachiopod from the Mead Hill deposits, though the shells of these Brachiopods are less well preserved so they are not formally described as a new species. There are ten of these Brachiopods, all conjoined valve pairs all deformed by crushing and tectonic deformation. They are subcircular in outline and have narrow, erect beaks.

 Second Mead Hills Brachiopod. (A-C) First specimen, complete shell in dorsal (A), lateral (B), and ventral (C), views. The exaggerated curvature of the ventral valve is due to tectonic distortion. (D-F) Second specimen, complete shell in dorsal (D), ventral (E), and lateral (F), views. The thin shell at the growth margins of both these specimens has been broken off. (G) Third specimen, complete shell in anterior view showing broken anterior end with portion of the loop visible (arrowed). Hiller (2016).

See also... elegans: An Early Cambrian Lophophorate Animal with affinities to Brachiopods and Phoronids.                   Lophophorates are animals which feed using a...
Brachiopods (or Lampshells) superficially resemble Bivalve Molluscs, though they are not closely related. They were abundant in the seas of the Palaeozoic, often dominating benthic faunas, but today are comparatively rare, and seldom seem outside the... tissue preservation in Linguloid Brachiopods from the Early Ordovician Fenxiang Formation of Hubei Province, China.                                                  

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Wednesday, 19 October 2016

Palaeopsilotreta xiai: A Caddisfly from Cretaceous Burmese Amber.

Caddisflies, Trichoptera, are an ancient Insect group with a fossil record dating back to the Triassic. However, as with many Insect groups, the majority of these specimens are compression fossils, which tend to preserve only the wings, useful for determining the presence of a group and even differentiating species, but telling us little about the actual Insects. This makes amber deposits, which often preserve whole Insects trapped in resin excreted by Trees, particularly interesting to palaeoentomologists (scientists who study fossil Insects), as these deposits show the whole morphology of the Insects, enabling information about their biology and ecology to be inferred.

In a paper published in the journal Cretaceous Research on 29 September 2016, Wilfried Wichard of the Institute of Biology at the Universityof Koeln, and Bo Wang of the State Key Laboratory of Palaeobiologyand Stratigraphy at the Nanjing Institute of Geology and Palaeontology and the Key Laboratory of Zoological Systematics and Evolution at the Institute of Zoology of the Chinese Academy ofScience, describe a new species of Caddisfly from Burmese Amber collected from a mine near the village of Noije Bum in Kachin State, Myanmar.

The new species is named Palaeopsilotreta xiai, where 'Palaeopsilotreta' means 'Ancient Psilotreta', PsilotretaI being a modern genus that the specimen closely resembles, and 'xiai' honours Xia Fangyuan of the Lingpoge Amber Museum for his work on Burmese Amber. The species is described from three male specimens, essentially similar to members of the modern genus Psilotreta, excepting their remarkable antennae, which are bipectinate along much of their length; that is to say they have a double row of rami (comb-like structures) on the antennae, with a pair of rami arising from each of the antennae joints.

Palaeopsilotreta xiai, first specimen. Wichard & Wang (2016).

Branching, comb-like or feathery structures on the antennae of Insects are generally associated with an improved sense of smell. Such structures are most common in Moths and Beetles and are typically found in species where the male locates females by following a pheromone scent she emits, and in such species it is usually only the males that have such antenae. No Caddisfly with bipectinate antennae has previously been recorded, though there are several species with pectinate antennae (i.e. antennae that have a single row of rami) known from modern Vietnam. Curiously, all of these modern Vietnamese species are known from their males only (i.e. no females have been found for any of these species), so it is unknown if the females of these species have simple or pectinate antennae, a situation also seen in Palaeopsilotreta xiai, which is described from male specimens only.

Second specimen of Palaeopsilotreta xiai. Wichard & Wang (2016).

Due to the close resemblance of Palaeopsilotreta xiai to the modern genus Psilotreta, it is considered to be a member of the same family, the Odontoceridae, a group with a fossil record that previously only extended back to the Eocene. Amber from the Noije Bum Mine is encased in a volcanoclastic matrix (i.e. a sediment of volcanic origin, typically an ashfall or lahar deposit), which has been dated to 98.8 million years ago using uranium-lead dating of zircon crystals (zircon is a mineral formed by the crystallization of cooling lavas; when it forms it often contains trace amounts of uranium, which decays into - amongst other things - lead at a known rate; since lead - which has a much lower melting point - will not have crystalized out of the original lava as the zircon formed, it is possible to calculate the age of a zircon crystal from the ratio between these elements.); it is assumed that the amber is slightly, but not significantly, older than the matrix, making the amber a little under 100 million years old.

See also... Caddisfly from the Middle Jurassic of Inner Mongolia.                                            Caddisflies (Trichoptera) are a widespread and numerous (over 12 000 described species) group of Insects closely related to the Lepidoptera (Butterflies and Moths). Like Butterflies and Moths...
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Asteroid 2016 TO11 passes the Earth.

Asteroid 2016 TO11 passed by the Earth at a distance of 895 500 km (2.33 times the average distance between the Earth and the Moon, 0.60% of the average distance between the Earth and the Sun), slightly after 7.00 pm GMT on Wednesday 12 October 2016. There was no danger of the asteroid hitting us, though had it done so it would have presented no threat. 2016 TO11 has an estimated equivalent diameter of 6-21 m (i.e. it is estimated that a spherical object with the same volume would be 6-21 m in diameter), and an object of this size would be expected to explode in an airburst (an explosion caused by superheating from friction with the Earth's atmosphere, which is greater than that caused by simply falling, due to the orbital momentum of the asteroid) in the atmosphere between 38 and 20 km above the ground, with only fragmentary material reaching the Earth's surface.

 The calculated orbit of 2016 TO11. Minor Planet Center.

2016 TO11 was discovered on 6 October 2016 (six days before its closest approach to the Earth) by the University of Arizona's Mt. Lemmon Survey at the Steward Observatory on Mount Lemmon in the Catalina Mountains north of Tucson. The designation 2016 TO11 implies that the asteroid was the 289th object (object O11) discovered in the first half of October 2016 (period 2016 T).

2016 TO11 has a 1084 day orbital period and an elliptical orbit tilted at an angle of 4.36° to the plain of the Solar System that takes it from 0.93 AU from the Sun (i.e. 93% of the average distance at which the Earth orbits the Sun) to 3.19 AU from the Sun (i.e. 319% of the average distance at which the Earth orbits the Sun, over twice the distance at which the planet Mars orbits the Sun). It is therefore classed as an Apollo Group Asteroid (an asteroid that is on average further from the Sun than the Earth, but which does get closer).

See also... (462959) 2011 DU passes the Earth.                                                     Asteroid  (462959) 2011 DU passed by the Earth at a distance of 5 828 000 km (15.2 times the average distance between the Earth and the Moon, or 3.90%... 2016 TH passes the Earth.       Asteroid 2016 TH passed by the Earth at a distance of 128 300 km (0.34 times the average distance between the Earth and the Moon, 0.09% of the average distance between the Earth and the Sun), at about 4.30 pm... 2016 TD passes the Earth.       Asteroid 2016 TD passed by the Earth at a distance of 226 200 km (0.59 times the average distance between the Earth and the Moon, 0.15% of the average distance between the Earth and the Sun), at about 5.15 pm GMT on Friday 30 September 2016...
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Magnitude 6.9 Earthquake beneath western New Britain.

The United States Geological Survey recorded a Magnitude 6.9 Earthquake at a depth of 35 km beneath western New Britain slightly before 4.15 pm local time (slightly before 6.15 am GMT) on Monday 17 October 2016. There are no reports of any casualties associated with this event, but many people on the island are reporting minor damage, and the event was felt on mainland Papua New Guinea.

The approximate location of the 17 October 2016 New Britain Earthquake. Google.

New Britain is located on the South Bismarck Plate, north of the Solomon Sea Plate, which is being subducted beneath it. The plates do not pass over one-another smoothly, but constantly stick together then break apart as the pressure builds up, causing Earthquakes in the process.

 The subduction of the Solomon Sea Plate beneath New Britain. Oregon State University.

Witness accounts of Earthquakes can help geologists to understand these events, and the structures that cause them. If you felt this event then you can report it to the Athens Institute of Geodynamics Here.

See also... 7.5 Earthquake off the east coast of New Britain.                                      The United States Geological Survey recorded a Magnitude 7.5 Earthquake at a depth of 10 km off... on Mount Tavurvur.                  Mount Tavurvur, an active stratovolcano (cone-shaped volcano) on the eastern part of the Rabul Caldera on the Island of New Britain, part of Papua New Guinea, underwent a major eruption on Friday 29 August.... 6.5 Earthquake beneath western New Britain.                                                     A Magnitude 6.5 at a depth of 63 km occurred beneath the interior of western New Britain Island, Papua New Guinea, at 6.30 am on...
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Tuesday, 18 October 2016

Ancient fluvial systems on Arabia Terra, Mars.

Modern Mars has an arid climate combined with an atmosphere to thin to support liquid water and a surface temperature seldom warm enough to allow ice to melt. However much of the surface of Mars shows evidence of a wetter climate in the past, with river systems, lakes and even shallow seas being identified by planetary scientists. This has led to the theory that during the Noachian Period, more than 3.7 billion years ago, Mars had a warmer, wetter climate with extensive precipitation (rainfall) and water dominated environments covering much of the surface of the planet. However some of the ancient terrains predicted by this model as having been likely to have had very wet climates during the Noachian are devoid of any signs of water. This has led to the development of an alternative climate model for ancient Mars, the Icy Highlands model, in which the climate of ancient Mars was still predominantly cold and dry, but with extensive glaciation forming in highland regions, particularly around the equator, and the water-created landforms of Mars being created by rare episodes of warming which melted these ice caps leading to catastrophic but short-lived floods.

In a paper published in the journal Geology on 23 August 2016, Joel Davies of the Department of Earth Sciences at University College London, Matt Balme of the Department of Physical Sciences at the Open University, Peter Grindrod of the Department of Earth and Planetary Sciences at Birkbeck College, University of London, Rebecca Williams of the Planetary Science Institute and Sanjeev Gupta of the Department of Earth Sciences and Engineering at Imperial College London describe evidence for a network of fluvial (river) channels covering much of the Arabia Terra, the largest of the 'dry' Noachian Terrains of Mars, and therefore one of the biggest obstacles to the Warm an Wet model of the ancient Martian climate.

These channels are detected in images produced by the Context Camera on the Mars Reconnaissance Orbiter, and take the form of sinuous ridges and branching systems rising up to 60 m above the surrounding terrain and flowing with and around topological features in a way that would be predicted for fluvial channels. Ridges are not an obvious sign of fluvial activity, but can be formed if river channels develop a more robust structure that the surrounding terrain, for example a stony riverbed or even river-bottom carbonate deposit in an area otherwise covered by loess (dusty, easily wind-blown soil), which can lead to the riverbed remaining as a raised, or 'inverted', channel after the surrounding terrain has been eroded away. Such inverted riverbeds are not purely theoretical they are familiar from desert regions on Earth, and are therefore to be expected on Mars if that planet once had a wet climate but has subsequently aridified.

Map showing distribution of inverted channels (black lines) and valley networks (white lines) in Arabia Terra, Mars, study area. Many of the inverted channels (e.g., southwest region of study area) are not associated with valley networks. Background image is Mars OrbitalLaser Altimeter gridded topographic map. Davies et al. (2016).

These channels are not evenly distributed across the Arabia Terra, but rather are concentrated in the southwest, with the northwest and east of the terrain largely devoid of such structures. This is consistent with large-scale water-flows from the north to the south, draining into the Meridiani Planum to the south and southwest of the Arabia Terra, though a number of streams appear to drain into other features, particularly craters that may once have held ancient lakes.
Mars Reconnaissance Orbiter Context Camera mosaics of (A) anabranching and sinuous inverted channel system (Aram Dorsum; candidate ExoMars landing site) in southwest Arabia Terra; and (B) branching and sinuous inverted channel system in southwest Arabia Terra, terminating in terraced, sub-circular feature consistent with inverted paleolake deposit. Both inverted channels are unconformably overlain by regional etched units. Davies et al. (2016).

Based upon the relationships of the channels to other geographic features, Davies et al. conclude that the channels were probably active in the Middle-to-Late Noarchian. The presence of the channels on the Arabia Terra, one of the largest areas on Mars on which fluvial structures had not previously been identified, lends considerable support to the warm and wet hypothesis of early Martian climate, a model which predicts a wet climate in the Arabia Terra region, and which was stretched by the absence of such evidence.

See also... recent volcanic activity in the Southern Highlands of Mars.                                 The planet Mars formed about 4.5 billion years ago, and is thought to have been highly volcanically active in its early history. However due to its smaller size it... silicate minerals in the Mariner Valley, Mars.                                             Hydrated minerals (minerals containing water) are considered to be evidence of the former presence of liquid water on Mars. They have been observed at a... landslide deposits in the Mariner Valley, Mars                                                              Landslides on Mars typically have much greater runout distances than those on Earth, due to the planets lower gravity and thinner atmosphere. This can...
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Monday, 17 October 2016

Utahcaris orion and the origin of the Chelicerates.

Burgess Shale-type faunas are fossil Lagerstätten which provide unique insights into life in the Early-to-Middle Cambrian. The best known examples of these are the highly productive Middle Cambrian Burgess Shale deposits of British Colombia and the Early Cambrian Chengjiang biota of South China, though other less productive sites are also known, such as the Middle Cambrian Spence Shale of northern Utah, which is slightly older than the Burgess Shale and has produced a wide variety of Algae, Sponges, Brachiopods, Eldoniids (soft-bodies animals of uncertain affinities), stem-Molluscs (animals of apparent Moluscan affinities, but which lived or split off from the other Molluscs before the common ancestor of all living groups), Cycloneuralians (the group that includes Kinorynches, Priapulids and Nematodes), Deuterostomes (the group that includes Vertebrates and Echinoderms), Lobopodians (the probable Cambrian ancestors of the Modern Velvet Worms), and a variety of Arthropods, including Trilobites, Carapace-bearing Arthropods (which may be related to the later Crustaceans), Megacheirans (an extinct group of probably predatory Arthropods), Xenopods (an extinct group of soft-bodied Arthropods) and enigmatic forms such as Meristosoma paradoxum and Utahcaris orion.

In a paper published in the Geological Magazine on 31 August 2016, DavidLegg of the Oxford University Museum of Natural History and Steve Pates of the Department of Zoology at the University of Oxford, redescribe the original specimen of Utahcaris orion plus a new specimen and discuss the relationship of this species to other Arthropods, in particular the highly successful Chelicerates (Arachnids, Horseshoe Crabs, their most recent common ancestor and everything descended from it).

The original specimen of Utahcaris orion was discovered by Benjamin Dattilo in Antimony Canyon, and was described by Simon Conway Morris and Richard Robinson in a paper published in TheUniversity of Kansas Paleontological Contributions in 1988. It is preserved as a compression fossil in dorsal view, 87 mm in length. This specimen has a large, subtriangular cephalic shield, plus eleven trunk and two abdominal segments. Remarkably this specimen also shows a section of preserved, phosphatized gut containing the fragmentary remains of a number of Trilobites.

 Utahcaris orion, Antimony Canyon specimen. (a) Part, photographed using polarized lighting, and (b) accompanying camera lucida drawing. Gut content is coloured grey. Abbreviations: P? – putative podomere; and T1–T11 – trunk tergites 1–11. Legg & Pates (2016).

The new specimen was discovered in Miners Hollow by Robert and Nancy Meyers, and is described for the first time, providing new insights into the species and its biology. This specimen is preserved in lateral (side) view, and shows a number of features not visible in the original specimen, notable a compound eye beneath the cephalon and several pairs of elongate flattened limbs.

 Additional specimen of Utahcaris orion from Miners Canyon. (a) Part, photographed using polarized lighting, and (b) accompanying camera lucida drawing. Gut content and eyes are coloured grey. Abbreviations: Ap – appendages; E – eye; and T1–T10 – trunk tergites 1–10. Legg & Pates (2016).

The original study of Utahcaris orion suggested that it might be related to Sanctacaris uncata, a fossil from the Burgess Shale which has been suggested to be the earliest known Chelicerate, as well as to the Leanchoiliid Megacheirans Actaeus, Alalcomenaeus, and Leanchoilia. The new specimen of Utahcaris orion reveals no further similarities to the Leanchoiliid Megacheirans, indicating that the similarities between Utahcaris and this group were a product of the limited nature of the material available rather than any true close biological relationship, however the relationship to Sanctacaris uncata is more strongly supported, and Legg and Pates suggest that these two species, along with Wisangocaris barbarahardyae (a species from the Ema Shale of South Australia to be described in a paper published on 13 May 2016 in the journal Palaeontology by James Jago, Diego Garcia-Bellído and James Gehling) be united as the Family Sanctacarididae, the earliest known Chelicerate group, and that as the Spence Shale is slightly older than the Burgess Shale, Utahcaris orion is therefore the oldest currently know Chelicerate.

The mouthparts of Utahcaris orion are unknown, however the closely related Sanctacaris uncata is known to have robust gnathobases (chewing organs), and the presence of fragmentary Trilobite remains in the gut of the first specimen of Utahcaris orion suggests that it may have had similar structures. This, combined with the presence of limbs apparently modified for swimming, strongly implies that the Chelicerates may have been active predatory animals from the outset, a lifestyle still seen in the majority of living species today.

See also... disjuncta: Enigmatic Cambrian fossil re-interpreted as a tub-dwelling vermiform Hemichordate.                                                The Hemichordates are Deuterostome Animals. members of the group which also... Scathascolex minor: A Palaeoscolecid Worm from the Middle Cambrian Burgess Shale of British Colombia.                            Palaeoscolecids are a group of vermiform animals (worms) known from Cambrian to Silurian deposits. They had rings similar to... rarus: A Kinorhynch from the Early Cambrian of Sichuan Province, China.                                                 Kinorhynches are tiny (at most 3 mm) worm like animals found in marine sediments, with segmented tube- or barrel-shaped bodies, separate head and neck regions and evertable pharynxes. They

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