Saturday, 19 October 2019

Evidence for a giant submarine landslide in the South China Sea at the Oligocene-Miocene boundary.

Submarine landslides are one of the most important processes for global sediment fluxes and tsunami generation. Such events can be massive, far larger than subaerial landslides; the largest known subaerial landslide, the Markagunt Gravity Slide, occurred about 22 million years ago in what is now Utah, and had a lateral extent of roughly 90 km. For comparison, the largest submarine landslide in the last decade was triggered by the 2011 Tōhoku Earthquake, had a lateral extent of 27.7 km, and far larger such events are recorded in the geological record; the Storegga Slide on the coast of Norway, which happened between 6225 and 6170 BC, had a lateral extent of about 290 km, and the Halibut Slide, which occurred between 62 and 64 million years ago on the west coast of Scotland was of similar size. 

In a paper published in the Journal of Marine Science and Engineering on 17 May 2019 Chaoqi Zhu of the Shandong Provincial Key Laboratory of Marine Environment and Geological Engineering at the Ocean University of China, and the Laboratory for Marine Geology at the Qingdao National Laboratory for Marine Science and Technology, Sheng Cheng, also of the Shandong Provincial Key Laboratory of Marine Environment and Geological Engineering at the Ocean University of China, Qingping Li of the Research Center of the China National O ffshore Oil Corporation, Hongxian Shan, also of the Shandong Provincial Key Laboratory of Marine Environment and Geological Engineering at the Ocean University of China, and the Laboratory for Marine Geology at the Qingdao National Laboratory for Marine Science and Technology, and the Key Lab of Marine Environment and Ecology, Jing’an Lu of the Guangzhou Marine Geological Survey, Zhicong Shen again of the Shandong Provincial Key Laboratory of Marine Environment and Geological Engineering at the Ocean University of China, and Xiaolei Liu and Yonggang Jia, once again of the Shandong Provincial Key Laboratory of Marine Environment and Geological Engineering at the Ocean University of China, the Laboratory for Marine Geology at the Qingdao National Laboratory for Marine Science and Technology, and the Key Lab of Marine Environment and Ecology, present evience for a gigantic submarine landslide in the Pearl River Mouth Basin of the South China Sea.

The Pearl River Mouth Basin has formed by continental rifting and sea floor spreading in the South China Sea area since the Early Cretaceous. The Baiyun Sag area of the Basin contains a succession of sediments laid down on the continental shelf edge on the outer opening of this basin, which contains the main reservoir of oil, gas, and gas hydrate in the northern South China Sea. However the area also contains numerous submarine landslide structures, many of which are buried or otherwise obscured, making them difficult to map accurately. At least 142 such mass transport complexes have been found in the submarine canyons of the Pearl River Mouth Basin.

 Geological map showing the Pearl River Mouth Basin. Zhu et al. (2019).

The present shelf break is aligned with the boundary between the Panyu Low Uplift and the Baiyun Sag. Sequence stratigraphy of the Baiyun Sag reveals that the shelf break has been located in its present position since about 23.8 million years ago, and that the Baiyun Sag was in a deep-water slope environment at that time. Previous studies of the evolutionary history of the shelf break showed that from about 23.8 million years ago swung back and forth around the boundary, although it stayed quite close to the present location. Continental shelf deltaic deposition is found in the Zhuhai Formation (laid down between 32 and 23.8 million years ago, and is characterised by southward progradational reflections with sigmoid-oblique configurations seen in seismic surveys. These deltaic deposits extend to the Baiyun Sag, where deepwater fan structures can be seen.

Delta structures contain sediment and other material from rivers, which is dumped when it reaches the sea forming the delta. Over time the organic material within the sediment forms pockets, which are then heated and crushed by the overlying sediment (increasing pressure also increases temperature, and vice versa, which is why aerosol sprays, undergoing rapid decompression, are cold), forcing water out of more complex organic compounds (dehydration) and forming pockets of gas and oil.

The main cause of shelf break migration is usually changes in sea level, combined with changes in sediment flow and other geological processes. The progressive seaward migration of the shelf break in the Baiyun Sag between 30 and 23.8 million years ago can be attributed to sedimentary supply and sea level changes, but at 23.8 million years ago (the Oligocene-Miocene boundary) there is a sudden shoreward shift from the south to north of the Baiyun Sag, which Zhu et al. attribute to a submarine landslide. This marks a change in the depositional environment on the Sag, before 23.8 million years ago it was in a shallow, shelf-edge environment, after 23.8 million years ago in a deep-water depositional environment, and the shelf break migrated from south to north of the Baiyun Sag.

 Multi-beam submarine geomorphology shadow map showing the Baiyun–Liwan submarine slide, the Baiyun slide, the Dongsha creep zone, and the shelf break line (SBL). The white dotted line is a scarp of the Baiyun–Liwan submarine slide. The brown dotted lines are the scarp of the Baiyun slide and range of the Dongsha creep zone, respectively. Zhu et al. (2019).

This change in depositional environment is marked in drill cores by a sharp decrease in the deposition rate, from a relatively high rate in the Oligocene to a very low rate in the Miocene, separated by what appear to be slumping related fault structures. The Oligocene and Miocene sediment were differentiated on the basis of microfossil analysis. The landslide structure extends laterally for over 250 km, and appears to show the movement of about 35 000 to 40 000 cubic kilometres of sediment.

Submarine landslides can be causes by a variety of phenomena, but very large events are almost always associated with major tectonic events. Zhu et al. suggest that the Baiyun Sag landslip is associated with slip-strike faulting (faulting in which the areas of land on either side of a fault move sideways relative to one-another) along the Red River Fault, around the Oligocene-Miocene boundary. This was associated with the movement of Southeast Asia about 500 km to the south, relative to South China, driven by the penetration of the Indian Plate into the Eurasian, and the formation of the Himalayan Mountains.

Simplified map showing the triggering mechanism of the Baiyun–Liwan submarine slide. Zhu et al. (2019).

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Florida Fish and Wildlife Conservation Commission breaks up a Turtle-smuggling ring.

The Florida Fish and Wildlife Conservation Commission has announced it has broken up a Turtle-smuggling ring operating out of Fort Myers in Lee County. The commission became involved in the case after a man and woman were stopped for a traffic offence in Charlotte County in May 2019, and were found to be in possession of 42 small Three-striped Mud Turtles, Kinosternon baurii, one Florida Softshell Turtle, Apalone ferox, and a 30 cm Alligator, Alligator mississippiensis. Concerned by this the Charlotte County Sheriff's Office contacted the Florida Fish and Wildlife Conservation Commission, who's enquiries led them to raid a property in Fort Myers in August where they seized several hundred more Turtles.

Turtles seized by the Florida Fish and Wildlife Conservation Commission in a raid on a property in Fort Myers in August 2019. The News Press.

The Turtles seized in Fort Myers include Florida Box Turtles, Terrapene carolina bauri, Eastern Box Turtles, Terrapene carolina carolina, Striped Mud Turtles, Kinosternon baurii, Florida Mud Turtles, Kinosternon subrubrum, Chicken Turtles, Deirochelys reticularia, Florida Softshell Turtles, Apalone ferox, Gulf Coast Spiny Softshell Turtles, Apalone spinifera aspera, Spotted Turtles, Clemmys guttata, and Diamondback Terrapins, Malaclemys terrapin. In addition body parts from a Kemp's Ridley Sea Turtle, Lepidochelys kempii, and a Black Bear, Ursus americanus, and a quantity of narcotics were confiscated.

Six hundred of the Turtles were returned to the wild almost immediately, and twenty four more after a period in quarantine, with another three hundred being monitored by the Sanibel-Captive Conservation Foundation, and a small number from species non native to Florida passed to a captive wildlife licensee.

 Turtles seized by the Florida Fish and Wildlife Conservation Commission in a raid on a property in Fort Myers in August 2019. The News Press.

Two men were arrested during the raid, Michael Boesenberg, 39, who is suspected of organising Turtle trapping across Florida and neighbouring states, and Michael Clemons, 23, of selling, possessing and transporting Turtles taken from the wild. It is thought that the Turtles were intended for export to Asia, where captive Turtles can be worth hundreds of dollars in the pet trade. 

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Siamraptor suwati: A new species of Allosauroid Dinosaur from the Early Cretaceous of Thailand.

The Tetanurans are a large subgroup of the Theropod Dinosaurs, including the Spinosaurs, Tyranosaurs, Ornithomimids, Maniraptors, Therizinosaurs, Oviraptors, Birds, Troodontids, Dromeosaurs, Allosaurs, Raptors and other groups. They appeared in the Middle Jurassic and different groups have flourished ever since, though only one group, the Birds, survived the end-Cretaceous extinction. The first of these groups to come to prominence were the Allosauroids and Megalosauroids, groups which began to produce large-bodied species in the Middle Jurassic, and dominated the top-predator roles in most terrestrial ecosystems until the early Late Cretaceous.

In a paper published in the journal PLoS One on 9 October 2019, Duangsuda Chokchaloemwong of the Northeastern Research Institute of Petrified Wood and Mineral Resources at Nakhon Ratchasima Rajabhat University, Soki Hattori of the Institute of Dinosaur Research at Fukui Prefectural University, and the Fukui Prefectural Dinosaur Museum, Elena Cuesta, also of the Institute of Dinosaur Research at Fukui Prefectural University, Pratueng Jintasakul, also of the Northeastern Research Institute of Petrified Wood and Mineral Resources at Nakhon Ratchasima Rajabhat University, and Masateru Shibata and Yoichi Azuma, again of the Institute of Dinosaur Research at Fukui Prefectural University, and the Fukui Prefectural Dinosaur Museum, describe a new species of Allosauroid Dinosaur from the Early Cretaceous Khok Kruat Formation of Nakhon Ratchashima Province in northeastern Thailand.

The Khok Kruat Formation forms the uppermost unit of the Khorat Group and is widely distributed in the Khorat Basin of northeastern Thailand. The formation is 430–700m thick and consists mainly of reddish-brown siltstones and sandstones, laid down in a fluvial (river) environment. The formation is of Aptian age, between 125 and 113 million years old. The Khok Kruat Formation has produced a number of Dinosaur fossils, most of them from the Ban Saphan Hin (Saphan Hin Village) site in the northwest of the Muang District in Nakhon Ratchashima Province, which has been excavated by the Japan-Thailand Dinosaur Project.

Locality map of new Theropod material and stratigraphy of Khorat Group. (A) map of Nakhon Ratchasima Province, Thailand; (B) distribution map of the Khok Kruat Formation in Nakhon Ratchasima Province; (C) enlarged locality map of Suranaree and Khok Kruat subdistricts with the subdistrict boundaries; (D) a photograph of the excavation site; (E) stratigraphic column of the Khorat Group. A red-coloured star indicates the new Theropod locality, the dotted lines indicate the subdistrict boundaries, and the grey-colored lines indicate the roads in (C) respectively. Chokchaloemwong et al. (2019).

The new species is named Siamraptor suwati, where 'Siamraptor' means 'Thailand thief' and 'suwati' honours Suwat Liptapanlop, who supports and promotes the work of the Northeastern Research Institute of Petrified Wood and Mineral Resources. The new species is described from disarticulated cranial and postcranial elements from at least three individuals. This material comprises three right premaxillae, a right and a left maxillae, a left jugal, two posterior parts of the left mandible comprising the surangular, prearticular, and articular, a posterior part of the left mandible comprising the surangular and prearticular, three anterior cervical vertebrae, three posterior dorsal vertebrae, a middle caudal vertebra, a manual ungual, a right ischium, a distal part of the right tibia, and a left pedal phalanx IV-1. All of these are materials were found in a small area (125 m x 160 m) of a single layer of a single locality, and the overlapping materials exhibit the same diagnostic features.

Skeletal reconstruction of Siamraptor suwati. Cranial elements were scaled to fit in with the holotype (surangular). Scale bar equals 1 m. Chokchaloemwong et al. (2019).

Siamraptor suwati is adjudged to be an Allosauroid on the basis of a straight ventral margin on the jugal (cheekbone), a dorsoventrally deep anterior process below the orbit, a surangular (bone at the back of the jaw) with a deep oval concavity at the posterior end of the lateral shelf and four posterior
surangular foramina (openings), a long and narrow groove along the suture between the surangular and prearticular bones, an articular bone with a foramen at the notch of the suture with prearticular bone, an anterior cervical vertebra (formost vertebra in the neck) with an additional pneumatic foramen in the  parapophysis (transverse processe that projects from the centrum of the vertebra), and cervical and posterior dorsal vertebrae penetrated by a pair of small foramina bilaterally at the base of neural spine. 

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Friday, 18 October 2019

Comet C/2018 N2 (ASASSN) makes its closest approach to the Earth.

Comet C/2018 N2 (ASASSN) will make its closest approach to the Earth on Sunday 20 October 2019, reaching a distance of 2.11 AU from the Earth (211% of the distance between the Earth and the Sun, or 330 880 000 km). At this distance the comet will be not naked eye visible, having a magnitude of slightly over 12, requiring a reasonably good telescope to see it, in the Constellation of Andromeda, which is better observed from the Northern Hemisphere, and viewing will be poor the approach comes seven days after the Full Moon on Sunday 13 October, so that the meteors may be obscured by the brightness of the Moon.

Image of C/2018 N2 (ASASSN) taken from Denver, Colorado, on 30 December 2018. The image is a composite of six 300 second exposures. The comet is the point near the centre of the image marked N2, the slightly elongate objects in the background are stars which have moved over the time of the exposure. Mike Olason/Sky & Telescope.

C/2018 N2 (ASASSN) was first observed on 16 July 2019 by the the 14-cm 'Cassius' survey telescope at Cerro Tololo as part of the All-Sky Automated Survey for Supernovae (ASASSN) program.. The name C/2018 N2 (ASASSN) implies that it was the second comet discovered in the second half of July 2018 (Period 2018 N), and that it was discovered by the All-Sky Automated Survey for Supernovae.

The orbit and position of Comet C/2018 N2 (ASASSN) at its closest approach to the Earth. The Sky Live 3D Solar System Simulator.

C/2018 N2 (ASASSN) is a Parabolic Comet, which is to say a comet that has been disrupted from an orbit in the Oort Cloud, and to be passing through the Inner Solar System on a parabolic orbit that will probably not bring it back again. This parabolic trajectory tilted at an angle of 77.5° to the plain of the Solar System, that brought it in to 3.12 AU from the Sun at perihelion (i.e. 3.12 times as far from the Sun as the planet Earth, or more than twice as far from the Sun as the planet Mars).

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Second dead whale found in Thames Estuary this month.

A Whale, believed to be an immature Fin Whale, Balaenoptera physalus, has been found in the Thames Estuary, England. The animal was found at Denton, near Gravesend on the morning of Friday 18 October 2019, according to the Port of London Authority, and has been removed so that a  necropsy (animal autopsy) can be carried out by the Zoological Society of London. The body of the Whale was discovered only ten days after the body of anouther Whale, an immature Humpback, Megaptera novaeangliae, that had been in the river for several days, was found dead near Greenhithe in Kent. A necropsy on that animal showed that it was severly undernourished at the time of death, and was suffering from a heavy parasite load, though the cause of death appeared to be a fractured jaw and associated large wound which appears to have bled heavily, and is thought to have been caused by a ship strike.

A dead Whale found in the Thames Estuary near Denton in Kent being winched out of the water to undergo a necropsy investigation. Triangle News.

This is the third Whale to have been found dead in the Thames Estuary this year, another Humpback having been found near Dartford in Kent on 12 September, and the fifth in the UK, with two strandings having been recorded in Northumbria. The previous most recent recorded Whale death in the UK was in 2009 when a juvenile male Humpback was found near Dartford. A Beluga Whale, Delphinapterus leucas, spent several months in the Thames Estuary in 2018, but eventually left of its own accord.

Many species of Whales were hunted almost to extinction in the nineteenth and twentieth centuries, prior to a moratorium on almost all Whale hunting that was introduced in the 1970s. The reporting of greater numbers of dead Whales on our shores is often distressing, and can appear to be sign of more Whales dying in inshore waters, but in fact this greater number of dead Whales reflects a larger population of Whales being present offshore, and is a symptom of recovering populations.

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Family of four feared dead after landslide in Elgeyo Marakwet County, Kenya.

A family of four are thought to have lost their lives following a landslide in the village of Kapkonder in Elgeyo Marakwet County, Kenya, on Friday 18 October 2019. The incident reportedly happened early in the morning while the family, described as two adults and two children, were sleeping, following several days of heavy rain in the area.Landslides are a common problem after severe weather events, as excess pore water pressure can overcome cohesion in soil and sediments, allowing them to flow like liquids. Approximately 90% of all landslides are caused by heavy rainfall.

 The approximate location of the 18 October 2019 Kapkondor Landslide. Google Maps.

Elgeyo Marakwet County lies within the Rift Valley of Kenya, and often suffers in flash floods, severe erosion and landslides on its escarpments following heavy rainfall events. The Rift Valley area has two Rainy Seasons per year, with a long rainy season that runs from March to May and a short rainy season than lasts from October to December. Such a double Rainy Season is common close to the equator, where the Sun is highest overhead around the equinoxes and lowest on the horizons around the solstices, making the solstices the coolest part of the year and the equinoxes the hottest. 

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Mirabad-e Emam Qoli: A Sassanid-era fire temple in south-eastern Iran.

The Sassanid kingdom ruled in Iran from 224 to 651 AD, at its peak ruling an empire that included Egypt, Afghanistan, much of the Arabian Peninsula and half of Anatolia, making it a serious rival to the Late Roman Empire. The Sassanids practised a form of Zoroastrianism, a religion which has its origins in ancient Persia, and which is still practised in India today. Zoroastrianism is considered to have been a major influence on Persian culture, which is still influential in modern Iran, though most religious structures associated with the religion were lost during the Islamic invasion between 637 and 651.

In a paper published in the journal Antiquity on 18 February 2019, Leyla Fazel and Yaghoub Mohammadifar of the Archaeology Department at Bu-Ali Sina University describe the remains of a Sassinid fire temple at Mirabad-e Emam Qoli, in the eastern part of Kerman Province in south-eastern Iran, that was discovered during an archaeological survey at the Bam World Heritage Site in 2013.

The fire temple is located 12 km to the north of Mohammadabad, the capital of Rigan County, on the the southern margin of the Kavir-e Lut (Lut Desert), and thus experiences an arid desert climate, windstorms and sandstorms. 

 Map of Iran, with location of the Mirabad-e Emam Qoli fire temple. Fazel & Mohammadifar (2019).

The temple is mostly covered with debris and sand up to the rise of the arches of the doorways, The walls are covered with clay and straw. The main part of the structure is currently situated below ground level and cannot be seen from a distance. The roofing has not survived in most parts of the building. There are extensions and additions to the building on all sides, the remnants of which have formed mounds around the main structure.

The structure consists of a single building featuring the typical characteristics of Sassanid religious architecture. The main building is a rectangular structure measuring 13 m by 17.4 m. The ground plan of this area includes a cruciform central chamber, four doorways on the four sides and a vestibule around the central space. The chamber in the centre measures 4 m by 4 m. The depth of the doorways is 3.3 m on the north side, and 2.1 m on the other three sides. The vestibules are 3.25 m wide along the north side, and nearly 1.3 m wide on the other sides. The vestibules lead to the area surrounding the fire temple through doorways in each of the four sides. Remnants of a chamber measuring 3.1 m by 5.4 m along the west side and another one measuring 3.3 by 3 m on the south side are still standing. The tallest part of the structure, along the eastern side, is 1.6m high. The building is mainly made of bricks measuring  40 cm by 40 cm by 10 cm.

Evidence from aerial images suggests that the fire temple was surrounded by several other buildings. The structures that can still be distinguished are located to the south-west of the temple, and stand on a mound approximately 5m in height. The ground plan is rectangular, measuring 31 m by 41 m. This was probably a castle, caravansary or a similar type of accommodation block. Such complexes are often associated with Sassanid fire temples and would have provided pilgrims and site attendants with accommodation.

Aerial image of the fire temple (top-right arrow) and the possible castle/caravansary/accommodation block (bottom-left arrow), made using Google EarthFazel & Mohammadifar (2019).

The most significant feature of this structure is the fire altar at the centre. The upper compartment of the altar is a cube measuring 1.6 m on each side, and has at least four stepped layers. This fire altar confirms the function of the structure as a fire temple. The visible part of the fire altar is made of large baked bricks covered with a gypsum plaster. The censer is covered with debris. There is a hole in one of the corners of the fire altar, which was presumably used to feed the flames with oils or other aromatic substances.

The visible parts of the fire altar are similar to those depicted on Sassanid coins, and to the stone fire altar of Qanat Baq. The fire altar is situated slightly below the rise of the eastern arch, which suggests that the fire altar pedestal originally feature a rather tall, column-like structure. The exact form of the main altar slab and its supports is, however, unknown due to the debris that covers them.

The east side of the fire temple. Leyla Fazel in Fazel & Mohammadifar (2019).

Theplanof this fire temple is similar to that of the Konar Siyah, Tol Jangi and Khormayak fire temples in Fars, the Negar fire temple in Kerman, the Juliyan fire temple in Abdanan and the Mil-e Milgah fire temple in Kermanshah. While these all date back to the Sassanid reign, finer chronological precision is not currently possible.

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