Provenance of Late Ordovician sedimentary rocks in the SE Yangtze block: Implications for deposition in an active continental margin

2020 ◽  
Vol 127 ◽  
pp. 103862
Author(s):  
Tao Yu ◽  
Zongqi Wang ◽  
Dongsheng Wang ◽  
Changqian Ma ◽  
Yingli Zhang ◽  
...  
Keyword(s):  
Continental Margin ◽  
Active Continental Margin ◽  
Sedimentary Rocks ◽  
Late Ordovician ◽  
Yangtze Block

scholarly journals Geochemical features, sources and geodynamic settings of accumulation of the cambrian sedimentary rocks of the Mel’gin trough (Bureya continental massif)

2019 ◽  
Vol 64 (5) ◽  
pp. 503-519
Author(s):  
R. O. Ovchinnikov ◽  
A. A. Sorokin ◽  
V. P. Kovach ◽  
A. B. Kotov
Keyword(s):  
Continental Margin ◽  
Active Continental Margin ◽  
Sedimentary Rocks ◽  
Detrital Zircons ◽  
Igneous Rocks ◽  
Early Cambrian ◽  
Relative Probability ◽  
Early Proterozoic ◽  
Geodynamic Settings ◽  
Probability Plots

The first data about geochemical features of the Cambrian sedimentary rocks of the Mel’gin trough of the Bureya continental Massif, as well as ages of detrital zircons of them are obtained. It is established, that among the detrital zircons from the sandstones of the Chergilen and Allin formations of the Mel’gin trough zircons with Late Riphean (peaks on relative probability plots – 0.78, 0.82, 0.94, 1.04 Ga) and Early Riphean (peaks on relative probability plots – 1.38, 1.45, 1.64 Ga) ages predominate. The single grains have a Middle Riphean, Early Proterozoic and Late Archean ages. We can suppose, that the sources of Late Riphean detrital zircons from sandstones of the Chergilen and Allin formations are igneous rocks of gabbro-granitoids (940–933 Ma) and granite- leucogranites (804–789 Ma) association, identified in the Bureya continental Massif. We can`t assume, what kind of rocks were the source for Middle Riphean and older detrital zircons from the Cambrian sedimentary rocks of the Bureya continental Massif, because in this massif still do not identified complexes older Late Riphean age. The most probable geodynamic conditions of accumulation of the Cambrian deposits of the Mel’gin trough is the conditions of active continental margin, which is corresponding to of Early Cambrian granitoids magmatism.

Neoproterozoic gabbro-granite association from the Micangshan area, northern Yangtze Block: Implication for crustal growth in an active continental margin

2017 ◽  
Vol 53 (6) ◽  
pp. 2471-2486 ◽  
Author(s):  
Shao-Cong Lai ◽  
Jiang-Feng Qin ◽  
Xiao-Ping Long ◽  
Yong-Fei Li ◽  
Yin-Juan Ju ◽  
...  
Keyword(s):  
Continental Margin ◽  
Active Continental Margin ◽  
Crustal Growth ◽  
Yangtze Block

Revisiting the tectonic evolution of the Triassic Palaeo-Tethys convergence zone in northern Thailand inferred from detrital zircon U–Pb ages

2020 ◽  
pp. 1-25
Author(s):  
Hidetoshi Hara ◽  
Tetsuya Tokiwa ◽  
Toshiyuki Kurihara ◽  
Thasinee Charoentitirat ◽  
Apsorn Sardsud
Keyword(s):  
Continental Margin ◽  
South China ◽  
Detrital Zircon ◽  
Active Continental Margin ◽  
Sedimentary Rocks ◽  
Convergence Zone ◽  
Accretionary Complex ◽  
Northern Thailand ◽  
Collision Zone ◽  
Back Arc

Abstract Detrital zircon U–Pb ages for sediments in and around the Palaeo-Tethyan convergence zone in northern Thailand provide constraints for tectonic interpretations of the Indochina Block, the Sibumasu Block, the Inthanon Zone accretionary complex and the Nan Back-arc Basin during the Triassic. In sedimentary rocks of the Indochina Block, almost all of the Palaeozoic and Triassic zircons were sourced from the collision zone between the Indochina and South China blocks, and an active continental margin in the western Indochina Block. Sediments of the Sibumasu Block were supplied by erosion of Archaean basement and from the Grenville and the Pan African orogenies, but show no record of Permian to Triassic igneous activity. Accretionary complex sediments have provenances of both the Sukhothai Arc and the Indochina and South China blocks, with detrital zircons of various ages being supplied from crustal uplift and erosion related to the Indosinian I orogeny. Sedimentary rocks of the Nan Back-arc Basin are widely distributed not only in the Nan–Uttaradit but also in northern Sukhothai areas. The origin of the Pha Som Metamorphic Complex and associated formations can be traced to basin-filling sediments in the Nan Back-arc Basin. These detrital zircon U–Pb ages have also allowed identification of the changing tectonic setting in the Palaeo-Tethys convergence zone from the ‘erosion of Proterozoic continental basement’ to ‘Palaeozoic active continental margin in the western Indochina Block’ and ‘Palaeozoic, Permian to Triassic collision zone between the South China and Indochina blocks’ through to ‘Triassic active Sukhothai Arc’.

Age and tectonic setting of the Nesåa Batholith: implications for Ordovician arc development in the Caledonides of Central Norway

2003 ◽  
Vol 140 (5) ◽  
pp. 573-594 ◽  
Author(s):  
G. B. MEYER ◽  
T. GRENNE ◽  
R. B. PEDERSEN
Keyword(s):  
Rare Earth ◽  
Partial Melting ◽  
Continental Margin ◽  
Tectonic Setting ◽  
Active Continental Margin ◽  
Shear Zones ◽  
Late Ordovician ◽  
Magma Ascent ◽  
Middle Ordovician ◽  
Laurentian Margin

New U–Pb zircon dating yields a crystallization age of 458±3 Ma for the largely gabbroic Grøndalsfjell Intrusive Complex in the Gjersvik Nappe of the Caledonian Upper Allochthon in Scandinavia. This is identical, within error, to the age of the adjacent Møklevatnet Complex that is dominated by quartz monzodiorite (456±2 Ma), and the two intrusive suites may be regarded as members of a composite intrusion here referred to as the Nesåa Batholith. Mafic members of this calc-alkaline batholith are characterized by slightly positive εNd–εSr values, marked enrichment of the light rare earth elements and high Th/Yb ratios suggestive of a subduction-modified mantle source. The I-type granitoids have similar isotope values and highly fractionated rare earth element patterns, and are interpreted as products from partial melting of garnet-bearing mafic rocks. The Nesåa Batholith intruded a previously deformed, 483 Ma or older, metavolcanic sequence of oceanic arc affinity. The margins of the pluton show evidence for synkinematic emplacement, which is tentatively interpreted in terms of magma ascent controlled by deep-seated shear zones. Further uplift and exhumation of the crystallized plutons was followed by rapid deposition of batholith-derived conglomerates and arkoses in a marginal basin represented by the Limingen Group. The age of the Nesåa Batholith fills the gap in reported ages for Caledonian magmatism, between the Early to Middle Ordovician, oceanic to continental margin type, arc sequences of Laurentian palaeotectonic affinity, and the Late Ordovician–Early Silurian batholith complexes of interpreted Laurentian margin affinity. It is interpreted as an early phase of the more extensive plutonism recorded in the Bindal Batholith of the Uppermost Allochthon to the west. Our model implies that the Early Ordovician oceanic arc sequences of the Gjersvik Nappe were deformed and accreted on to Laurentian margin lithologies prior to Late Ordovician times. This composite crustal assemblage was the source for the voluminous quartz monzodioritic intrusions of the Nesåa Batholith, which formed by partial melting due to ponding of subduction-related mantle derived mafic magmas either within or at the base of the active continental margin.

scholarly journals Paleozoic and Early Mesozoic terrigenous deposits of the South-West Primorye: material composition and origin

2020 ◽  
Author(s):  
А.И. МАЛИНОВСКИЙ
Keyword(s):  
Continental Margin ◽  
Active Continental Margin ◽  
Volcanic Rocks ◽  
Sedimentary Rocks ◽  
Source Area ◽  
Material Composition ◽  
Clastic Material ◽  
Power Sources ◽  
Early Mesozoic ◽  
South West

Рассматриваются результаты изучения вещественного состава палеозойских–раннемезозойских терригенных отложений Лаоелин-Гродековского террейна (юго-западное Приморье). Цель исследования – палеогео­динамическая реконструкция обстановок формирования отложений изученных свит, а также определение типов и породных составов их источников питания. Установлено, что отложения свит существенно различаются по вещественному составу, следовательно, они формировались в различных палеогеодинамических обстановках. Отложения кордонкинской свиты накапливались в бассейне, связанном с океанической островной дугой, при этом областью их питания была сама дуга, сложенная основными и средними вулканитами, а также магматическими и осадочными образованиями, входившими в состав ее фундамента. Накопление решетниковской свиты происходило в бассейнах, расположенных на пассивной континентальной окраине. Источниками вещества служили участвовавшие в строении этой окраины кратоны и краевые части рифтов, сложенные гранитоидами, метаморфическими и осадочными породами. Тальминская свита формировалась на активной континентальной окраине в бассейнах рифтогенного происхождения. Источниками кластического материала были краевые части этих рифтов, сложенные кислыми и средними изверженными, а также метаморфическими породами. Полученные результаты позволяют рассматривать Лаоелин-Гродековский террейн как аккреционную призму, сложенную силурийскими, пермскими и триасовыми образованиями, сформировавшимися в различных палеогеодинамических обстановках. Results of material composition study of Paleozoic–Early Mesozoic terrigenous deposits of Laoeling-Grodekovo terrane (South-West Primorye) are collected. The purpose of the study was to reconstruct paleogeodynamic setting of deposits of studied formations, as well as to determine the types and rock compositions of their power sources. It was established that the deposits differ significantly in their material composition and, accordingly, were formed in different paleogeodynamic settings. Deposits of the Kordonka formation accumulated in the basin associated with the oceanic island arc, while the source area was the arc itself, composed of basic and intermediate volcanic rocks, as well as igneous and sedimentary formations that were part of its foundation. The accumulation of the Reshetnikovka formation took place in basin located on the passive continental margin. The sources of the matter were the cratons and marginal parts of rifts participating in the structure of this margin, composed of granitoids, metamorphic, and sedimentary rocks. The accumulation of the Tal’mi formation took place on the active continental margin in the basins of riftogenic origin. The sources of the clastic material were the marginal parts of these rifts, composed of acidic and intermediate igneous Laoeling-Grodekovo terrane as an accreationary prism formed by Silurian, Permian and Triassic deposits, which were formed in various paleogeodynamic settings.

Geochemical and isotope composition of pebbles from the Caban Conglomerate Formation and their bearing on the source of Welsh Palaeozoic sedimentary rocks

1992 ◽  
Vol 129 (5) ◽  
pp. 581-587 ◽  
Author(s):  
J. A. Evans
Keyword(s):  
Continental Margin ◽  
Igneous Rock ◽  
Isotope Composition ◽  
Active Continental Margin ◽  
Sedimentary Rocks ◽  
Geochemical Composition ◽  
Nd Isotope ◽  
Ree Geochemistry ◽  
Depleted Mantle ◽  
Igneous Origin

AbstractMajor, trace and REE geochemistry, together with Nd isotope determinations, provide new insights into the provenance of seven pebbles of igneous origin from an early Silurian facies of the Caban Conglomerate Formation from central Wales. The geochemical composition of the pebbles supports formation in a subduction related environment on an active continental margin. Biotite whole-rock Rb-Sr systematics constrain the age of a granite pebble to 650±38 Ma. The pebbles provide discrete examples of Avalonian basement which contributed to the isotope composition of sedimentary rocks in the Welsh Basin and one granite pebble provides a rare example from the Welsh Basin of an igneous rock with a Palaeoproterozoic depleted mantle model age.

Geochemistry of the Laiyang Group from outcrops and Lingke-1 core on Lingshan Island, Shandong Province, Eastern China: implications for provenance, tectonic setting and palaeo-environment

2021 ◽  
pp. 1-18
Author(s):  
Qing Ma ◽  
Yaoqi Zhou ◽  
Hongyu Mu ◽  
Tengfei Zhou ◽  
Hanjie Zhao ◽  
...  
Keyword(s):  
Continental Margin ◽  
Lower Cretaceous ◽  
Tectonic Setting ◽  
Eastern China ◽  
Active Continental Margin ◽  
Sedimentary Rocks ◽  
Source Rocks ◽  
Oceanic Anoxic Event ◽  
Weathering Processes ◽  
Geochemical Indices

Abstract Lower Cretaceous sedimentary rocks of Lingshan Island, located along the continental margin of East Asia, have received increased attention. The Lingke-1 core mainly belongs to the Lower Cretaceous Laiyang Group. We investigate provenance, tectonic setting, palaeoclimate and palaeoredox conditions in the study area using elemental geochemistry, thereby elucidating the depositional history of the Lower Cretaceous sediments and reconstructing the palaeo-environment. To achieve this, 90 siltstones and 76 mudstones were sampled from this core and other outcrops on Lingshan Island. The chemical index of alternation (CIA) values for the majority of the samples and the bivariate diagrams indicate that the sedimentary rocks were subjected to minor weathering processes. Geochemical results suggest that source rocks for the region are felsic igneous and metamorphic rocks, along with minor proportions of intermediate igneous rocks. Major- and trace-element discrimination diagrams, deciphering the tectonic history, indicate that source rocks mainly originated from the continental island-arc and active continental margin. Several representative geochemical indices and the bivariate plots based on elemental contents show that the Laiyang Group was predominantly deposited in arid conditions. Sr/Ba values suggest a palaeosalinity transition from brackish to saline, demonstrating a depositional transformation from lacustrine facies for the lower Laiyang Group to marine facies in the upper Laiyang Group. U/Th and V/(V+Ni) ratios and Ce anomalies in the rocks indicate anoxic conditions. We conclude that the conspicuous decline in the trends of the above three geochemical indices, ranging between 400 and 800 m, may be related to the latest Hauterivian oceanic anoxic event.

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