scholarly journals Origin and age of the Shenshan tectonic mélange in the Jiangshan-Shaoxing-Pingxiang Fault and late Early Paleozoic juxtaposition of the Yangtze Block and the West Cathaysia terrane, South China

2021 ◽  
Author(s):  
Lijun Wang ◽  
Kexin Zhang ◽  
Shoufa Lin ◽  
Weihong He ◽  
Leiming Yin
Keyword(s):  
South China ◽  
Strike Slip ◽  
Carbonaceous Shale ◽  
Early Paleozoic ◽  
Yangtze Block ◽  
The West ◽  
Northern Margin ◽  
The North ◽  
Tectonic Mélange ◽  
Different Parts

When and how the Yangtze Block (Yangtze) and the West Cathaysia terrane (West Cathaysia) in South China were amalgamated are critical to a better understanding of the Neoproterozoic to early Paleozoic tectonic evolution of South China and remain highly debatable. A key to this debate is the tectonic significance of the Jiangshan-Shaoxing-Pingxiang (JSP) Fault, the boundary between Yangtze and West Cathaysia. The Shenshan mélange along the JSP Fault has the typical block-in-matrix structure and is composed of numerous shear zone-bounded slivers/lenses of rocks of different types and ages that formed in different tectonic environments, including middle to late Tonian volcanic and volcanogenic sedimentary rocks (turbidite) of arc/back-arc affinity, a series of middle Tonian ultramafic to mafic plutonic rocks of oceanic island basalt affinity, a carbonaceous shale that was deposited in a deep marine environment, and a red mudstone. U-Pb zircon ages and acritarch assemblages (Leiosphaeridia-Brocholaminaria association) found in the turbidite confirm its Tonian age, and fossils from the carbonaceous shale (Asteridium-Comasphaeridium and Skiagia-Celtiberium-Leiofusa) constrains its age to the Early to Middle Cambrian. Field relationships and available age data leave no doubt that the ultramafic-mafic rocks are exotic blocks (rather than intrusions) in the younger metasedimentary rocks. We conclude that the Shenshan mélange is not an ophiolitic mélange, but rather a tectonic mélange that formed as a result of movement along the JSP Fault in the early Paleozoic. We suggest that Yangtze and West Cathaysia were two separate microcontinents, were accreted to two different parts of the northern margin of Gondwana in the early Early Paleozoic, and juxtaposed in the late Early Paleozoic through strike-slip movement along the JSP Fault. We further suggest that the ca. 820 Ma collision in the Jiangnan Orogen took place between Yangtze and a (micro)continent that is now partly preserved as the Huaiyu terrane and was not related to West Cathaysia. We compare our model for South China with the accretion of terranes in the North American Cordillera and propose a similar model for the relationship between the Avalon and Meguma terranes in the Canadian Appalachians, i.e., the two terranes were accreted to two different parts of the Laurentian margin and were later juxtaposed through margin-parallel strike slip faulting.

scholarly journals Supplemental Material: Origin and age of the Shenshan tectonic mélange in the Jiangshan-Shaoxing-Pingxiang Fault and late Early Paleozoic juxtaposition of the Yangtze Block and the West Cathaysia terrane, South China

2021 ◽  
Author(s):  
Lijun Wang ◽  
Shoufa Lin ◽  
et al.
Keyword(s):  
South China ◽  
Mixture Modeling ◽  
Early Paleozoic ◽  
Yangtze Block ◽  
The West ◽  
Tectonic Mélange

Photos of acritarchs, table of U-Pb zircon data and results of mixture modeling of U-Pb zircon data from the Shenshan tectonic mélange of South China.

scholarly journals Supplemental Material: Origin and age of the Shenshan tectonic mélange in the Jiangshan-Shaoxing-Pingxiang Fault and late Early Paleozoic juxtaposition of the Yangtze Block and the West Cathaysia terrane, South China

2021 ◽  
Author(s):  
Lijun Wang ◽  
Shoufa Lin ◽  
et al.
Keyword(s):  
South China ◽  
Mixture Modeling ◽  
Early Paleozoic ◽  
Yangtze Block ◽  
The West ◽  
Tectonic Mélange

Photos of acritarchs, table of U-Pb zircon data and results of mixture modeling of U-Pb zircon data from the Shenshan tectonic mélange of South China.

scholarly journals Multi-Level Detachment Deformation of the West Segment of the South Dabashan Fold-and-Thrust Belt, South China: Insights From Seismic-Reflection Profiling

2021 ◽  
Vol 9 ◽  
Author(s):  
Hanyu Huang ◽  
Qinghua Mei ◽  
Dengfa He ◽  
Renqi Lu ◽  
Yingqiang Li
Keyword(s):  
South China ◽  
Late Jurassic ◽  
Lower Triassic ◽  
Drill Hole ◽  
Structural Deformation ◽  
Yangtze Block ◽  
The South ◽  
The West ◽  
Northern Margin ◽  
Multi Level

The South Dabashan arcuate tectonic belt located at the northern margin of the Yangtze Block in South China, which primarily comprises a series of northwestern (NW)-trending foreland fold-and-thrust belts (FTBs), is useful for determining the intracontinental orogeny processes of the Yangtze Block. In this study, we integrated the latest pre-stack depth migration of three- and two-dimensional seismic profiles, drill hole, and outcrop data to explore the structural geometric and kinematic features of the west segment of the South Dabashan FTB. This belt is characterized by multi-level detachment structures due to the presence of three predominant sets of weak layers: the Lower Triassic Jialingjiang Formation gypsum interval, Silurian mudstone beds, and Cambrian shale beds. The belt is accordingly subdivided vertically into three structural deformation systems. The upper system appears above the Jialingjiang Formation gypsum layer and exhibits Jura-type folds, which were formed by alternating anticlines and synclines that are parallel to each other. The middle system comprises Silurian shale as the base and Jialingjiang Formation gypsum interval as the passive roof and exhibits NW-striking imbricate thrusts. The lower system is bounded by Cambrian and Silurian detachment layers, forming a duplex structure. The Sinian and Proterozoic basements below the Cambrian were not involved in deformation. The west segment of the South Dabashan FTB underwent four periods of tectonic evolution: Late Jurassic to Early Cretaceous, Late Cretaceous, Paleogene, and Neogene to Quaternary. The deformation was propagated southward in imbricate style, resulting in the passive uplifting of the overlying strata. Based on the magnetotelluric and deep seismic profile, the tectonic processes of the west segment of the South Dabashan FTB are inferred to be primarily controlled by the Yangtze Block northward subduction under the Qinling Orogenic Belt and the pro-wedge multi-level thrusting during the Late Jurassic to Cretaceous.

scholarly journals The state of mental health in the Philippines

2004 ◽  
Vol 1 (6) ◽  
pp. 8-11 ◽  
Author(s):  
Udgardo Juan L. Tolentino
Keyword(s):  
Mental Health ◽  
South China Sea ◽  
South China ◽  
The Philippines ◽  
Land Area ◽  
The South ◽  
The West ◽  
The North ◽  
The Pacific ◽  
The Pacific Ocean

The Philippines, known as the Pearl of the Orient, is an archipelago of 7107 islands, bounded on the west by the South China Sea, on the east by the Pacific Ocean, on the south by the Sulu and Celebes Sea, and on the north by the Bashi Channel. The northernmost islands are about 240 km south of Taiwan and the southernmost islands approximately 24 km from Borneo. The country has a total land area of some 300 000 km2. It is divided into three geographical areas: Luzon, Visayas and Mindanao. It has 17 regions, 79 provinces, 115 cities, 1495 municipalities and 41 956 barangays (the smallest geographic and political unit). It has over 100 ethnic groups and a myriad of foreign influences (including Malay, Chinese, Spanish and American).

The Late Cenozoic evolution of the Aksu basin (Isparta Angle; SW Turkey). New insights

2011 ◽  
Vol 182 (2) ◽  
pp. 133-148 ◽  
Author(s):  
André Poisson ◽  
Fabienne Orszag-Sperber ◽  
Erdal Kosun ◽  
Maria-Angella Bassetti ◽  
Carla Müller ◽  
...  
Keyword(s):  
Coral Reefs ◽  
Normal Faults ◽  
The West ◽  
Shallow Marine ◽  
Northern Margin ◽  
Sea Level Fluctuations ◽  
Marine Deposits ◽  
The North ◽  
Sw Turkey ◽  
Isparta Angle

Abstract The Mio-Pliocene basins around the Antalya gulf in SW Turkey developed above the Tauric Mesozoic platforms on which the Antalya nappes had been thrusted (in Late Cretaceous-Paleocene times). The closure of the initial Isparta Angle during these events (E-W compression) initiated the N-S orientation of the main structural lines, which persisted later and explains the orientation of the Aksu basin in contrast with the E-W orientation of the eastern Neo-gene Mediterranean basins. The area, and all southwestern Turkey, became emergent at the end of the Oligocene and were the site of shallow-marine carbonate deposits in the Chattian-Aquitanian, giving way to the wide Lycian basin in Burdigalian-Langhian times. The progressive emplacement of the Lycian nappes from the north over this basin provoked first its subsidence and then its emersion when the nappes attained their final position over the Bey Daglari platform in Langhian times. Coinciding, or in response to the Lycian nappes emplacement, the Aksu basin was initiated as an elongated N-S graben which was filled by thick accumulations of terrestrial and marine deposits(including coral reefs), which derived from the erosion of the Lycian allochton and its basement (Langhian?, Serravallian and Tortonian times). The syn-sedimentary tectonics : reactivation of the normal faults along the west margin of the basin, the continuous uplift of the neighbouring continental areas (beginning of the Aksu thrust), governed the geometry of the basin. As a result and due to the uplift of its northern margin, the Aksu basin migrated towards the south and in Messinian times it was reduced to a narrow gulf along the eastern margin of which the Gebiz limestones were deposited as fringing coral reefs. The age of these limestones has been debated. Our new data allow us to attribute them to the Messinian. The drastic retreat of the sea at the end of this period, provoked the erosion of large parts of the Messinian deposits and the formation of deep canyons on land and under the sea down to the Antalya abyssal plain, in which evaporites were deposited. During the Zanclean transgression, the Eskiköy-Kargi canyon was filled by coarse clastics of a Gilbert delta derived from the northern continental area following a model well known elsewhere in the Mediterranean basins. Southward, shallow-marine sands and marls unconformably cover the remnants of the Messinian deposits and the emergent areas of the southern Antalya gulf. After Zanclean times (end of Pliocene?), the Aksu basin was deformed, due to the west-directed Aksu compressional event (end of the Aksu thrust). Quaternary terraces of the Aksu river at various altitudes, as well as the terraces of the Antalya tufa can be related to sea level fluctuations.

V.—Two Bronze Age Cairns in South Wales: Simondston and Pond Cairns, Coity Higher Parish, Bridgend

Archaeologia ◽  
1938 ◽  
Vol 87 ◽  
pp. 129-180 ◽  
Author(s):  
Cyril Fox
Keyword(s):  
Bronze Age ◽  
East Side ◽  
The West ◽  
Northern Margin ◽  
The North ◽  
Outstanding Feature ◽  
South Wales ◽  
The Town

In the angle between the rivers Ogwr and Ewenny on the northern margin of the Vale of Glamorgan, east of the town of Bridgend, Brackla Hill (287 ft.) is the outstanding feature. Its pastoral slopes are linked to higher ground on the north by a saddle, on the east side of which there is a gentle fall to a tributary of the Ewenny, and on the west to a rivulet which flows into the Ogwr. Coity village lies at the point where the saddle merges into the upland.

scholarly journals A reconstruction of Iberia accounting for W-Tethys/N-Atlantic kinematics since the late Permian-Triassic

2020 ◽  
Author(s):  
Paul Angrand ◽  
Frédéric Mouthereau ◽  
Emmanuel Masini ◽  
Riccardo Asti
Keyword(s):  
Plate Boundary ◽  
Strike Slip ◽  
Late Permian ◽  
Seismic Profiles ◽  
The West ◽  
Geological Evidence ◽  
The North ◽  
Kinematic Evolution ◽  
Well Data ◽  
Strike Slip Movement

Abstract. The West European kinematic evolution results from the opening of the West Neotethys and the Atlantic oceans since the late Paleozoic and the Mesozoic. Geological evidence shows that the Iberian domain well preserved the propagation of these two rift systems and is therefore key to significantly advance our understanding of the regional plate reconstructions. The Late Permian-Triassic tectonic evolution of Iberian rift basins shows that they have accommodated significant extension, but this tectonic stage is often neglected in most plate kinematic models, leading to the overestimation of the movements between Iberia and Europe during the subsequent Mesozoic (Early Cretaceous) rift phase. By compiling existing seismic profiles and geological constraints along the North Atlantic margins, including well data over Iberia, as well as recently published kinematic and paleogeographic reconstructions we propose a coherent kinematics model of Iberia that considers both the Neotethyan and Atlantic evolutions. Our model shows that the Europe-Iberia plate boundary was a domain of distributed and oblique extension made of two rift systems, in the Pyrenees and in the Iberian intra-continental basins. It differs from standard models that consider left-lateral strike-slip movement localized only in the northern Pyrenees in introducing a significant strike-slip movement south of Ebro accounting for Late Permian-Triassic extension and by emphasizing the need for an Ebro microcontinent. At a larger scale it emphasizes the role played by the late Permian-Triassic rift and magmatism, as well as strike-slip faulting in the evolution of the western Neotethyan Ocean and their control on localization of the Atlantic rift.

A Tarim-North India connection in northern Gondwana: Constraints from provenance of early Paleozoic sedimentary rocks in the Altyn Tagh orogen, southeastern Tarim

2021 ◽  
Author(s):  
Qian Liu ◽  
Toshiaki Tsunogae ◽  
Guochun Zhao ◽  
Yigui Han ◽  
Jinlong Yao ◽  
...  
Keyword(s):  
South China ◽  
East Asian ◽  
Sedimentary Rocks ◽  
Detrital Zircons ◽  
Early Paleozoic ◽  
The North ◽  
Altyn Tagh ◽  
Tarim Craton ◽  
Tethys Ocean ◽  
Final Closure

<p>Amalgamation of northern Gondwana involves a wealth of present-day East Asian blocks (e.g., South China, North China, Alxa, Tarim, Indochina, Qiangtang, Sibumasu, Lhasa, etc.) due to consumption and closure of the Proto-Tethys Ocean. Locating the Tarim craton during assembly of northern Gondwana remains enigmatic, with different models separating Tarim from Gondwana by a paleoceanic domain throughout the Paleozoic, advocating a long-term Tarim-Australia linkage in the Neoproterozoic to the early Paleozoic, or suggesting a Tarim-Arabia connection in the early Paleozoic.</p><p>This study carried out field-based zircon U-Pb dating and Hf isotopic analyses for early Paleozoic sedimentary rocks in the Altyn Tagh orogen, southeastern Tarim. New dating results revealed that the early Paleozoic sedimentary rocks were deposited from ca. 494 to 449 Ma. Provenance tracing indicates the ca. 494-477 Ma sedimentary rocks were primarily sourced from the local Altyn Tagh orogen to the south of the North Altyn Ocean (one branch of the Proto-Tethys Ocean between southeastern Tarim and northern Gondwana). In contrast, the ca. 465-449 Ma sedimentary rocks have remarkably increasing ca. 840-780 Ma, 2.0-1.7 Ga, and 2.7-2.4 Ga detrital zircons, indicating an augmented supply of detritus from the Tarim craton to the north of the North Altyn Ocean. Such a significant provenance shift between ca. 477 and 465 Ma marks the timing of the final closure of the North Altyn Ocean. Combined with the timing of the final closure of other branches of the Proto-Tethys Ocean, the entire Proto-Tethys Ocean might have been progressively closed at ca. 500-420 Ma, resulting in the connection of most East Asian blocks with northern Gondwana. Based on detrital zircon U-Pb-Hf isotopic comparison, Tarim most likely shared a North Indian affinity with many East Asian blocks (such as North Qilian, North Qinling, South China, Indochina, South Qiangtang, etc.). This new finding argues against an Australian or Arabian affinity for the Tarim craton.</p><p>This work was financially supported by National Natural Science Foundation of China Projects (grants 41730213, 42072264, 41902229, 41972237, and 41888101), Hong Kong Research Grants Council General Research Fund (grant 17307918), and Grant-in-Aids for Scientific Research from Japan Society for the Promotion of Science (JSPS) to Prof. Toshiaki Tsunogae (No. 18H01300) and to Dr. Qian Liu (No. 19F19020). JSPS fellowship is also much appreciated.</p>

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