scholarly journals Relationships between Alluvial Facies/Depositional Environments, Detrital Zircon U-Pb Geochronology, and Bulk-Rock Geochemistry in the Cretaceous Neungju Basin (Southwest Korea)

Minerals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1023
Author(s):  
Hyojong Lee ◽  
Min Gyu Kwon ◽  
Seungwon Shin ◽  
Hyeongseong Cho ◽  
Jong-Sun Kim ◽  
...  
Keyword(s):  
Continental Margin ◽  
Detrital Zircon ◽  
Tectonic Setting ◽  
Active Continental Margin ◽  
Depositional Environments ◽  
Source Rocks ◽  
Bulk Rock ◽  
Zircon Age ◽  
Margin Setting ◽  
Weathering Intensity

Zircon U-Pb geochronology and bulk-rock geochemistry analyses were carried out to investigate their relationship with depositional environments of the non-marine Neungju Basin sediments in South Korea. The Neungju Basin was formed in an active continental margin setting during the Late Cretaceous with associated volcanism. Detrital zircon age distributions of the Neungju Basin reveal that the source rocks surrounding the basin supplied sediments into the basin from all directions, making different zircon age populations according to the depositional environments. Mudstone geochemistry with support of detrital zircon U-Pb age data reveals how the heterogeneity affects the geochemical characteristics of tectonic setting and weathering intensity. The sediments in the proximal (alluvial fan to sandflat) and distal (playa lake) environments differ compositionally because sediment mixing occurred exclusively in the distal environment. The proximal deposits show a passive margin signature, reflecting their derivation from the adjacent metamorphic and granitic basement rocks. The distal deposits properly indicate an active continental margin setting due to the additional supply of reworked volcaniclastic sediments. The proximal deposits indicate a minor degree of chemical weathering corresponding to fossil and sedimentological records of the basin, whereas the distal deposits show lower weathering intensity by reworking of unaltered volcaniclastic detritus from unstable volcanic and volcaniclastic terranes. Overall, this study highlights that compositional data obtained from a specific location and depositional environments may not describe the overall characteristic of the basin.

The tectonic setting of the eastern margin of the Sino-Korean Block inferred from detrital zircon U–Pb age and Nd isotope composition of the Pyeongan Supergroup (upper Palaeozoic – Lower Triassic), Korea

2017 ◽  
Vol 156 (3) ◽  
pp. 471-484 ◽  
Author(s):  
MUN GI KIM ◽  
YONG IL LEE ◽  
TAEJIN CHOI ◽  
YUJI ORIHASHI
Keyword(s):  
Detrital Zircon ◽  
Isotope Composition ◽  
Tectonic Setting ◽  
Active Continental Margin ◽  
Lower Triassic ◽  
Zircon Age ◽  
Nd Isotope ◽  
Eastern Margin ◽  
Late Palaeozoic ◽  
Nd Isotope Composition

AbstractThe upper Palaeozoic succession (Pyeongan Supergroup) in central eastern Korea is well correlated with the equivalent successions distributed in North China, suggestive of the Korean upper Palaeozoic being part of the Sino-Korean Block. Detrital zircon U–Pb ages and Sm–Nd isotope compositions of the Pyeongan Supergroup in the Samcheok coalfield of the Taebaeksan Basin were analysed. A single predominant zircon age peak at c. 1.9 Ga (> 70%) is marked in all sedimentary units, followed by varying amounts of minor late Palaeozoic grains (up to 30%). The rarity of Meso- to Neoproterozoic- and Silurian-aged zircons confirms that sediment influx from the South China and Qinling blocks was insignificant. The 2.0–1.8 Ga-dominated zircon age pattern and the Nd isotope composition (average εNd(0) = −15.5±4.0) of the Pyeongan Supergroup most closely reflect the signature of the Yeongnam Massif basements, which supports a previous hypothesis that the Pyeongan Supergroup was mostly derived from a palaeo-orogen located to the east–southeast. Relatively higher εNd(0) values (> −10.1) in the lowermost and the upper parts of the succession are closely matched by the increased occurrence of syn-depositional-aged zircons, which indicates considerable mixing of juvenile materials at c. 320 Ma and 260 Ma. Both arc-related magmatic events are interpreted to have been related to oceanic subduction, suggesting that the eastern margin of the Sino-Korean Block was an active continental margin during late Palaeozoic times.

Reassessment of the Mesozoic metasedimentary rocks and tectonic setting of Taiwan and the adjacent continental margin of eastern Asia

2016 ◽  
Vol 154 (5) ◽  
pp. 1127-1154 ◽  
Author(s):  
YU WANG ◽  
CHIN-HO TSAI ◽  
LIYUN ZHOU ◽  
YAN QIU ◽  
GUIHUA SUN
Keyword(s):  
Continental Margin ◽  
Tectonic Setting ◽  
Active Continental Margin ◽  
Crystalline Basement ◽  
Detrital Zircons ◽  
Source Rocks ◽  
Metamorphic Belt ◽  
Late Mesozoic ◽  
Sedimentary Sequences ◽  
Se China

AbstractIt remains unclear whether a crystalline basement exists in SE China (including Taiwan), whether the formation of the Tananao metamorphic belt in Taiwan was linked to subduction of the Palaeo-Pacific Plate, and whether the source rocks of the sedimentary sequences in the metamorphic belts are late Mesozoic or Palaeozoic in age. Field investigations and zircon age data in the present study indicate that there is no pre-Palaeozoic gneiss (crystalline basement) in Taiwan (although orthogneisses were produced during deformation and metamorphism of Mesozoic granites), and investigations of the metasediments show that the sedimentary sequences in the Tailuko and Yuli belts are similar. Moreover, LA-ICP-MS dating of detrital zircons from the Pingtan–Dongshan belt in Fujian Province yields a cluster of 206Pb–238U ages at ~ 210–190 Ma, and the Tailuko and Yuli belts in Taiwan have similar clusters of detrital zircon ages at 200 Ma, 160 Ma, 120 Ma and 110 Ma, as well as a later overprinting caused by arc–continent collision. The cathodoluminescence images and trace-element characteristics of the zircons show that they were originally magmatic in origin. This finding, combined with the Hf isotope data, indicates that the sources of sediments in the Tananao belt (Tailuko and Yuli belts) were relatively close to an active continental margin, and that both the Tailuko and Yuli belts have similar sedimentary sources. From the margin of the Chinese mainland to Taiwan, the metasediments seem to represent a continuous sequence of deposits ranging in age from Jurassic to Cretaceous, but with the sediments becoming progressively younger towards the east. It can be inferred that the sediments in the Tailuko and Yuli belts were continental-shelf sequences with sources in SE China.

scholarly journals U-Pb Detrital Zircon Ages and Geochemical Features of the Jingxing Formation, (Qamdo Basin, Tibet: Implications): Inferences for the Metallogenic Model of the East Tethys Evaporite

Minerals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 745
Author(s):  
Wenhua Han ◽  
Haizhou Ma ◽  
Weixuan Fang ◽  
Huaide Cheng ◽  
Yongshou Li ◽  
...  
Keyword(s):  
Trace Elements ◽  
Continental Margin ◽  
Detrital Zircon ◽  
Tectonic Setting ◽  
Active Continental Margin ◽  
Age Distribution ◽  
Major And Trace Elements ◽  
Jinsha River ◽  
The North ◽  
Detrital Zircon Ages

Qamdo basin is located between the suture zone of Jinsha River (Ailao Mountains) and that of Ban Gong Lake (Nujiang) in the eastern Tethys. Part of the Jingxing Formation is deposited in the southwest of the basin. In this study, two profiles were investigated from the north and south of Qamdo basin. The characteristics of detrital zircon LA-ICP-MS U-Pb age, and the main and trace elements of sandstone were analyzed. The characteristics of major and trace elements showed that the tectonic setting of the study area is mainly composed of a relatively stable active continental margin and a passive continental margin, showing characteristics of a continental island arc. The weathering degree of Jingxing Formation in the Qamdo area is lower than that in the Lanping-Simao area, which may be closer to the origin. The age distribution characteristics of detrital zircon grains indicate that the Qiangtang Block, Youjiang basin, and Yangtze area jointly constitute the provenance of the Qamdo-Lanping-Simao basin. Both basins may be part of a large marine basin with unified water conservancy connection before evaporite deposition. Metamorphic seawater from the Qamdo basin may migrate to the Lanping-Simao basin and even the Khorat basin, where evaporite was deposited.

scholarly journals Geochemistry, Depositional and Tectonic setting of the Barail Group of the Indo-Myanmar Ranges

2021 ◽  
Vol 38 (1) ◽  
pp. 13-22
Author(s):  
Salam Ranjeeta Devi
Keyword(s):  
Continental Margin ◽  
Chemical Weathering ◽  
Depositional Environment ◽  
Tectonic Setting ◽  
Active Continental Margin ◽  
Source Rocks ◽  
Humid Climate ◽  
Geochemical Study ◽  
High Degree ◽  
Semi Arid

The present paper deals with the study of the depositional environment and tectonic setting during the sedimentation of the Barail Group of rocks of the Indo-Myanmar Ranges (IMR). The Barail Group (Oligocene) consist of sandstone intercalated with shale and siltstone. Geochemical study suggests low to high degree of chemical weathering. ICV vs. CIA, Al2O3 vs. TiO2 diagrams indicate that the sediments were derived from the multiple source rocks dominantly of mafic composition. Arid to semi-arid/semi-humid climate prevailed during the deposition of the Barail Group sediments. Sedimentation occurred in a tectonic setting of overlap of passive to active continental margin under marine environment.

scholarly journals Geochemical Characteristics, Palaeoenvironment and Provenance of Uranium-Bearing Sandstone in the Sifangtai Formation, Northern Songliao Basin, Northeast China

Minerals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1019
Author(s):  
Yan Li ◽  
Feng-Jun Nie ◽  
Li-Cheng Jia ◽  
Sheng-Jun Lu ◽  
Zhao-Bin Yan
Keyword(s):  
Continental Margin ◽  
Tectonic Setting ◽  
Active Continental Margin ◽  
Thick Layer ◽  
Songliao Basin ◽  
Geochemical Characteristics ◽  
Source Rocks ◽  
Geochemical Data ◽  
Water Medium ◽  
Semi Arid

During the Cretaceous period of the northern Songliao Basin (northeast of China), a 100 m thick layer of fluvial-phase sandstone (Sifangtai Formation) with uranium potential was widely deposited, but its geochemical characteristics, paleoenvironment, and provenance remain unknown. This research proposes a new set of relevant geochemical data for sandstones to investigate their paleoenvironment, provenance and tectonic setting. The results revealed that: (1) The sandstone of the Sifangtai Formation was dominated by feldspar lithic sandstone. Geochemical signatures demonstrate that these sandstones have a high silicon content (SiO2 = 68.30~83.60 wt%) and total alkali content, but are poor in magnesium and calcium. They are also enriched in Rb, Th, U, K and LREE, and depleted HFSE (e.g., Nb, Ta), with crustal magmatic source. (2) The paleoclimate discriminant indicated that the rocks of the Sifangtai Formation might that the climate of Sifangtai Formation is semi-arid, and the chemical weathering of the source rocks is weak under the semi-arid climate environment. (3) The combination of element Sr/Ba, 100 MgO/Al2O3 and the combination of v/v + Ni, V/Cr, Ni/Co, and Sr/Cu indicated that the paleo-water medium was deposited in an oxygen-rich freshwater environment when the Sifangtai Formation was deposited. (4) The discriminate diagrams showed that almost all the sandstones of the Sifangtai Formation fell in the range of the active continental margin, indicating that the source area of the sandstones of Sifangtai Formations is an active continental margin tectonic environment, and the source is a felsic rock developed in the Xiaoxing’an Ridge and Zhangguangcailing area.

Geochemical signatures of recent bar deposits in the Tista river, Bangladesh: Implications to provenance, paleoweathering and tectonics

2020 ◽  
Vol 60 ◽  
pp. 1-20
Author(s):  
Pradip Kumar Biswas ◽  
M. Shafiqul Alam ◽  
A.S.M. Mehedi Hasan ◽  
Syed Samsuddin Ahmed ◽  
Mohammad Nazim Zaman
Keyword(s):  
Chemical Weathering ◽  
Tectonic Setting ◽  
Active Continental Margin ◽  
Granulite Facies ◽  
Depositional Environments ◽  
Source Rocks ◽  
Low Grade ◽  
Geochemical Composition ◽  
The North ◽  
Rock Types

Petrography and geochemical composition of sediments is a sensitive indicator which archives the signature of a previous record of a source rock and depositional environments in a basin.  This study deals with the elemental geochemistry of recent bar deposits of the Tista river in the north western part of Bangladesh to evaluate their provenance, paleoweathering and tectonic setting. Petrographically, the sediments are rich in quartz (70%), whereas feldspar and lithic fragments are found about 8% and 3%, respectively. The geochemical composition of the samples exhibits dominantly quartzose litharenites with low grade sedimentary and metasedimentary lithics, low feldspar indicates tectonic provenance field of recycled orogeny. Discrimination functions revels that the sediments of the Tista river are the derivation of active continental margin. The analyses also reflect that the sediments are dominantly a mixture of felsic (e.g., granitic/Gneiss, quartzite, amphibolite, granulite facies rock types) and some of mafic source (e.g., alkali-basalt/greenschist facies). It may occur, since 60% of the sedimentary flux carried out by the river from low-grade metamorphic rock and the rest from high-grade rock (in the west and north Sikkim Himalaya respectively). The weathering indices highlight that the source rocks have not undergone significant chemical weathering. The immature sorting status and petrographic evidences indicate that the sediments deposited in the Tista river basin are simply the product of mechanically weathered rocks.

Permian fragmentation, accretion and subsequent translation of a low-latitude Tethyan seamount to the high-latitude east Gondwana margin: evidence from detrital zircon age data

2002 ◽  
Vol 139 (2) ◽  
pp. 131-144 ◽  
Author(s):  
PETER A. CAWOOD ◽  
CHARLES A. LANDIS ◽  
ALEXANDER A. NEMCHIN ◽  
SHIGEKI HADA
Keyword(s):  
New Zealand ◽  
Subduction Zone ◽  
Continental Margin ◽  
Detrital Zircon ◽  
Detrital Zircons ◽  
Source Rocks ◽  
Low Latitude ◽  
Zircon Age ◽  
Current Location ◽  
Gondwana Margin

Ion microprobe analyses of detrital zircons in the Te Akatarawa Terrane, New Zealand, reveal that the age of unfossiliferous turbidites overlying a fusuline- and coral-bearing limestone block olistostromal mélange is no older than 255±4 Ma (Late Permian). This is approximately 15 m.y. younger than the Kungurian age of the fusulinid limestone. We interpret this to indicate collapse of a Permian oceanic seamount as it entered a subduction zone along the Pacific margin of Gondwana. These turbidites differ markedly in composition from adjoining Permian to Middle Triassic sand-stones of the Torlesse Terrane. Detrital zircon age data indicate predominantly Permian and Carboniferous ages for source rocks supplying the Te Akatarawa turbidites, but also reveal significant earlier Palaeozoic and Proterozoic components, ranging back to 1.9 Ga. The warm-water setting of limestone blocks and the short 15 m.y. time period between sedimentation and accretion onto a continental margin require the limestone to have formed in a low-latitude position probably off the northeast Australian (New Guinea) margin of Gondwana. Zircons within the sample underwent re-crystallization at around 230±11 Ma which may be related to alteration during accretion in a subduction zone environment. Over a period of 100 to 150 m.y. from 255 Ma the terrane underwent more than 5000 km translation along the continental margin southward to its current location as an exotic mini-terrane enclosed within the New Zealand Torlesse Terrane.

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.

Neoproterozoic active margin in the northwestern Yangtze Block, South China: new clues from detrital zircon U–Pb geochronology and geochemistry of sedimentary rocks from the Hengdan Group

2020 ◽  
pp. 1-17
Author(s):  
Bo Hui ◽  
Yunpeng Dong ◽  
Feifei Zhang ◽  
Shengsi Sun ◽  
Shuai He
Keyword(s):  
South China ◽  
Detrital Zircon ◽  
Active Continental Margin ◽  
Geodynamic Setting ◽  
Provenance Analysis ◽  
Yangtze Block ◽  
Essential Information ◽  
Zircon Age ◽  
Age Patterns ◽  
Depositional Age

Abstract The Yangtze Block in South China constitutes an important Precambrian landmass in the present East Asian continent. The Neoproterozoic sedimentary successions of the Hengdan Group in the NW Yangtze Block record essential information for deciphering the Neoproterozoic tectonics along the NW margin. However, its depositional age, provenance and tectonic properties remain uncertain. Here, a combined analysis of detrital zircon U–Pb dating and geochemistry is performed on representative samples from the Hengdan Group. Concordant dating results of samples from the bottom and upper parts constrain the maximum depositional age at c. 720 Ma. Detrital zircon age patterns of samples reveal a uniformly pronounced age peak at c. 915–720 Ma, which is consistent with the magmatic pulses in domains at the NW end of the Yangtze Block. In addition, these samples display left-sloping post-Archaean Australian shale (PAAS)-normalized rare-earth element patterns and variable trace element patterns, resembling sediments accumulated in a basin related to an active continental margin geodynamic setting. Provenance analysis reveals that the main sources featured intermediate to felsic components, which experienced rapid erosion and sedimentation. These integrated new investigations, along with previous compilations, indicate that the Hengdan Group might have been deposited in a fore-arc basin controlled by subduction beneath the Bikou Terrane. Thus, such interpretation further supports proposals for subduction-related tectonics along the western margin of the Yangtze Block during the early Neoproterozoic.

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