scholarly journals Current-controlled sedimentation in the north-western Weddell Sea

2021 ◽  
Vol 67 (4) ◽  
pp. 382-393
Author(s):  
L. G. Leitchenkov ◽  
V. V. Minina ◽  
Yu. B. Guseva
Keyword(s):  
Seismic Data ◽  
Middle Miocene ◽  
Sedimentary Basins ◽  
Weddell Sea ◽  
Sediment Wave ◽  
The North ◽  
Contourite Drifts ◽  
Antarctic Expedition ◽  
Russian Antarctic Expedition ◽  
North Western

The sedimentary basins of the north-western Weddell Sea are characterized by a variety of contourite drifts. This study is aimed at their identification, spatial mapping and temporal evolution and based on the integration of a large amount of seismic data collected by different countries including the recent data of the Russian Antarctic Expedition. Most of the drifts in the region being studied are classified as separated, confined, plastered or sheeted. The chain of sediment wave fields is mapped in the western and northern Powell Basin. The earliest contourite drifts started to form in the Early Miocene or, possibly, in the Late Oligocene. The changes in the depositional pattern in the Middle Miocene and then in the Late Pliocene are thought to have resulted from successive intensification of the bottom currents.

scholarly journals The two-stage Aegean extension, from localized to distributed, a result of slab rollback acceleration

2016 ◽  
Vol 53 (11) ◽  
pp. 1142-1157 ◽  
Author(s):  
Jean-Pierre Brun ◽  
Claudio Faccenna ◽  
Frédéric Gueydan ◽  
Dimitrios Sokoutis ◽  
Mélody Philippon ◽  
...  
Keyword(s):  
Middle Miocene ◽  
Middle Eocene ◽  
Sedimentary Basins ◽  
Ductile Deformation ◽  
Metamorphic Rocks ◽  
Western Anatolia ◽  
Two Stage ◽  
The North ◽  
Slab Rollback ◽  
Slab Tearing

Back-arc extension in the Aegean, which was driven by slab rollback since 45 Ma, is described here for the first time in two stages. From Middle Eocene to Middle Miocene, deformation was localized leading to (i) the exhumation of high-pressure metamorphic rocks to crustal depths, (ii) the exhumation of high-temperature metamorphic rocks in core complexes, and (iii) the deposition of sedimentary basins. Since Middle Miocene, extension distributed over the whole Aegean domain controlled the deposition of onshore and offshore Neogene sedimentary basins. We reconstructed this two-stage evolution in 3D and four steps at Aegean scale by using available ages of metamorphic and sedimentary processes, geometry, and kinematics of ductile deformation, paleomagnetic data, and available tomographic models. The restoration model shows that the rate of trench retreat was around 0.6 cm/year during the first 30 My and then accelerated up to 3.2 cm/year during the last 15 My. The sharp transition observed in the mode of extension, localized versus distributed, in Middle Miocene correlates with the acceleration of trench retreat and is likely a consequence of the Hellenic slab tearing documented by mantle tomography. The development of large dextral northeast–southwest strike-slip faults, since Middle Miocene, is illustrated by the 450 km long fault zone, offshore from Myrthes to Ikaria and onshore from Izmir to Balikeshir, in Western Anatolia. Therefore, the interaction between the Hellenic trench retreat and the westward displacement of Anatolia started in Middle Miocene, almost 10 Ma before the propagation of the North Anatolian Fault in the North Aegean.

scholarly journals EFFECTS OF SLAB ROLLBACK ACCELERATION ON AEGEAN EXTENSION

2017 ◽  
Vol 50 (1) ◽  
pp. 5 ◽  
Author(s):  
J.-P. Brun ◽  
C. Faccenna ◽  
F. Gueydan ◽  
D. Sokoutis ◽  
M. Philippon ◽  
...  
Keyword(s):  
Middle Miocene ◽  
Middle Eocene ◽  
Sedimentary Basins ◽  
Ductile Deformation ◽  
Western Anatolia ◽  
Localized Deformation ◽  
The North ◽  
Dynamic Relationship ◽  
Slab Rollback ◽  
Slab Tearing

Aegean extension is a process driven by slab rollback that, since 45 Ma, shows a twostage evolution. From Middle Eocene to Middle Miocene it is accommodated by localized deformation leading to i) the exhumation of high-pressure metamorphic rocks from mantle to crustal depths, ii) the exhumation of high-temperature rocks in core complexes and iii) the deposition of Paleogene sedimentary basins. Since Middle Miocene, extension is distributed over the whole Aegean domain giving a widespread development of onshore and offshore Neogene sedimentary basins. We reconstructed this two-stage evolution in 3D at Aegean scale by using available ages of metamorphic and sedimentary processes, geometry and kinematics of ductile deformation, paleomagnetic data and available tomographic models. The restorationmodel shows that the rate of trench retreat was around 0.6 cm/y during the first 30 My and then accelerated up to 3.2 cm/y during the last 15 My. The sharp transition observed in the mode of extension, localized versus distributed, which occurred in Middle Miocene correlates with the acceleration of trench retreat and is more likely a consequence of the Hellenic slab tearing documented by mantle tomography. The development of large dextral NE-SW strike-slip faults during the second stage of Aegean extension, since Middle Miocene, is illustrated by the 450 Km-long fault, recently put in evidence, offshore from Myrthes to Ikaria and onshore from Izmir to Balikeshir, in western Anatolia. Therefore, the interaction between the Hellenic trench retreat and the westward displacement of Anatolia started in Middle Miocene,almost 10 Ma before the propagation of the North Anatolian Fault in the North Aegean. This raises a fundamental issue concerning the dynamic relationship between slab tearing and Anatolia displacement.

scholarly journals The biochronology and palaeobiogeography of Baru (Crocodylia: Mekosuchinae) based on new specimens from the Northern Territory and Queensland, Australia

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3458 ◽  
Author(s):  
Adam M. Yates
Keyword(s):  
Middle Miocene ◽  
New Records ◽  
Drainage System ◽  
Northern Territory ◽  
Valid Species ◽  
Late Oligocene ◽  
Drainage Basins ◽  
Local Fauna ◽  
The North ◽  
North Western

New records of the Oligo–Miocene mekosuchine crocodylian, Baru, from Queensland and the Northern Territory are described. Baru wickeni and Baru darrowi are accepted as valid species in the genus and their diagnoses are revised. Both species are present in Queensland and the Northern Territory but are restricted in time, with B. wickeni known from the late Oligocene and B. darrowi from the middle Miocene. The broad geographic distributions and restricted time spans of these species indicate that this genus is useful for biochronology. The record of B. wickeni from the Pwerte Marnte Marnte Local Fauna in the Northern Territory establishes that the species inhabited the north-western margin of the Lake Eyre Basin (LEB) drainage system. More southerly Oligo–Miocene sites in the LEB contain only one crocodylian species, Australosuchus clarkae. The Pwerte Marnte Marnte occurrence of B. wickeni indicates that the separation of Baru and Australosuchus did not correspond with the boundaries of drainage basins and that palaeolatitude was a more likely segregating factor.

Ore geological studies of the Citronen Fjord zinc deposit, North Greenland: project ‘Resources of the sedimentary basins of North and East Greenland’

1997 ◽  
pp. 44-49
Author(s):  
Karsten Kragh ◽  
Sven Monrad Jensen ◽  
Henrik Fougt
Keyword(s):  
Sedimentary Basins ◽  
Geological Mapping ◽  
Zinc Deposit ◽  
East Greenland ◽  
The North ◽  
Diamond Drilling ◽  
Field Season ◽  
Research Councils ◽  
North Western ◽  
North Greenland

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Kragh, K., Monrad Jensen, S., & Fougt, H. (1997). Ore geological studies of the Citronen Fjord zinc deposit, North Greenland: project ‘Resources of the sedimentary basins of North and East Greenland’. Geology of Greenland Survey Bulletin, 176, 44-49. https://doi.org/10.34194/ggub.v176.5060 _______________ The multidisciplinary research project ‘Resources of the sedimentary basins of North and East Greenland’ was initiated in 1995 with financial support from the Danish Research Councils (Stemmerik et al., 1996). In the 1996 field season, ore geological studies continued on the shale-hosted Citronen Fjord zinc-lead prospect in North Greenland (Figs 1, 2). Platinova A/S discovered the deposit in 1993, and has subsequently explored the area by means of geological mapping, gravity surveys and diamond drilling. About 30 km of diamond drilling have been completed, and a resource of over 20 million tons of stratiform ore with 7% zinc and 1% lead has been estimated (Platinova A/S, 1996a, b). An additional fault-controlled, high-grade zinc-mineralised zonewas encountered in the north-western part of the ‘Discovery Zone’ in 1996 (Platinova A/S, 1996b).

Petrographical Notes on the Rock-Specimens collected in the Little Island of Trinidad, S. Atlantic, by the Antarctic Expedition of 1839–43, under Sir James Clark Ross

1900 ◽  
Vol 12 (58) ◽  
pp. 317-323 ◽  
Author(s):  
G. T. Prior
Keyword(s):  
Atlantic Ocean ◽  
West Indies ◽  
South Atlantic Ocean ◽  
Western Coast ◽  
The West ◽  
The North ◽  
Antarctic Expedition ◽  
The Antarctic ◽  
North Western ◽  
Rock Specimens

The Little Island of Trinidad, as it is called to distinguish it from the larger island in the West Indies, is situated in the South Atlantic Ocean, about 700 miles off the coast of Brazil, in lat. 20°31' S. and long. 29°19' W.According to Ross, who in 1839 effeeted a landing on tile N.W. coast, the island is a mass of volcanic matter, the rocks of which it is composed assuming the most extraordinary shapes. The most remarkable of these are the Sugar Loaf Hill on the southern and the Nine-Pin Rock on the north-western coast.

scholarly journals XXX.—Shackleton Antarctic Expedition, 1914–1917: Depths and Deposits of the Weddell Sea

1921 ◽  
Vol 52 (4) ◽  
pp. 781-793 ◽  
Author(s):  
J. M. Wordie
Keyword(s):  
Deep Sea ◽  
Weddell Sea ◽  
Western Area ◽  
North Eastern ◽  
Antarctic Expedition ◽  
Extreme North ◽  
North Western ◽  
Made In

Previous to the voyage of the Endurance in 1914–1915, the depth and extent of the Weddell Sea were either based on or surmised from the deep-sea soundings made on the Scotia by Dr Bruce in 1903 and 1904; on Dr Otto Nordenskjöld's ship Antarctic in 1901–1902; and on the German Expedition ship Deutschland under the leadership of Lieut. Filchner in 1912–1913. The first set are confined to the eastern and north-eastern portion, and may be said to run diagonally across the mouth of the sea; the second set were made in the extreme north-western area; whilst those of the Deutschland are disposed right down the centre of the sea, and consist mainly of a south-to-north series approximately along the meridian of 43° W.

scholarly journals IV.—The Temperatures, Specific Gravities, and Salinities of the Weddell Sea and of the North and South Atlantic Ocean

1916 ◽  
Vol 51 (1) ◽  
pp. 71-169
Author(s):  
William S. Bruce ◽  
Andrew King ◽  
David W. Wilton
Keyword(s):  
Atlantic Ocean ◽  
Physics Of The Ocean ◽  
South Atlantic ◽  
Weddell Sea ◽  
South Atlantic Ocean ◽  
The Past ◽  
The North ◽  
Franz Josef Land ◽  
Antarctic Expedition ◽  
North And South

After my return from my first voyage, namely, the Scottish Antarctic Expedition of 1892–93, for which I was chosen as naturalist, I had the advantage of coming closely in touch with Mr J. Y. Buchanan, who then trained me in his Edinburgh laboratory in the use of his hydrometer. During the past twenty years I have been in constant touch with him regarding problems relating to the physics of the ocean. As a consequence, before my departure for a voyage to, and wintering in, Franz Josef Land during 1896–97, I was well trained in the use of his hydrometer, and obtained during that expedition observations of considerable interest. I also carried out all the hydrometer work on board the Prince of Monaco's yacht Princess Alice during his Arctic voyage of 1898, under the direction of Mr J. Y. Buchanan, who was also on board during that cruise, and also during the Prince of Monaco's second Arctic cruise during 1899, when I was solely responsible for that work. Consequently, I was thoroughly familiar with hydrometer work when I set sail in the Scotia.

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