Late Mesozoic Paleo-Pacific Plate “scissors-like” subduction: Insight from the magmatism in the Gan-Hang Belt, Southeast China

2020 ◽  
Author(s):  
Liu Boran ◽  
Zhao Xilin ◽  
Yu Shengyao ◽  
Jiang Yang ◽  
Mao Jianren ◽  
...  
Keyword(s):  
Continental Margin ◽  
Middle Jurassic ◽  
Tectonic Setting ◽  
Pacific Plate ◽  
Geochemical Data ◽  
Asian Continent ◽  
Southeast China ◽  
Late Mesozoic ◽  
Extensional Tectonic ◽  
Roll Back

Though it is widely accepted that the Paleo-Pacific Plate has a subducted beneath the eastern Asian continent, controversy still exists regarding the initial timing and geodynamic model of the subduction. In this contribution, we report new geochronology and geochemical data of granitic plutons within the Gan-Hang Belt in Southeast China. The Damaoshan pluton yields zircon U-Pb ages of 139.60 ± 0.69 Ma and 133.90 ± 1.70 Ma, and the Qianshan and Fenglonggu plutons are dated at 135.70 ± 1.30 Ma and 135.33 ± 0.93 Ma, respectively. The Hecun and Huangtuling plutons yield ages of 157.85 ± 0.77 Ma and 167.10 ± 7.50 Ma, respectively. The Damaoshan pluton has an obvious A-type geochemical signature in terms of major and trace element compositions, such as high K2O+Na2O contents (average 8.46 wt%) and FeOT/MgO ratios (average 10.29). The low CaO/Na2O ratios but high Al2O3/TiO2 (average is 110.05), Rb/Ba (average is 9.14), and Rb/Sr (average is 22.53) ratios indicate a derivation from pelite-derived melt. Meanwhile, we also studied the Mesozoic adakites related to magmatic ore formed during a compressive tectonic setting as well as the later bimodal dikes and A-type granitic plutons formed during the extensional tectonic setting in the Gan-Hang Belt. The multiphase qualitative plutons with geochemical characteristics of the adakitic and island arc types (175−150 Ma) related to the northwestward subduction of the Paleo-Pacific Plate, several bimodal dikes, and A-type granitic plutons (135−123 Ma) related to the subducted slab roll-back are found within the Gan-Hang Belt. All of these plutons show a decreasing trend of isotopic ages from the inland area to the coast, from SW to NE. We propose that the distribution pattern of these plutons in Southeast China was controlled by a scissors-like subduction and slab roll-back of the Paleo-Pacific Plate, which occurred roughly from SW to NE along the continental margin approximately during the Middle Jurassic to the Early Cretaceous.

Three late-Mesozoic fluorite deposit belts in southeast China and links to subduction of the (paleo-) Pacific plate

2020 ◽  
pp. 103865
Author(s):  
Haibo Yan ◽  
Xing Ding ◽  
Mingxing Ling ◽  
Congying Li ◽  
Daniel E. Harlov ◽  
...  
Keyword(s):  
Pacific Plate ◽  
Southeast China ◽  
Late Mesozoic

scholarly journals Neoproterozoic Nafun Group Sediments from Oman Affected by an Active Continental Margin

Minerals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 511
Author(s):  
Liang Yue ◽  
Veerle Vandeginste
Keyword(s):  
Continental Margin ◽  
Water Oxidation ◽  
Tectonic Setting ◽  
Active Continental Margin ◽  
Trace Element Analysis ◽  
Deep Ocean ◽  
Geochemical Data ◽  
Ocean Water ◽  
Element Analysis ◽  
Deep Ocean Water

The Neoproterozoic era is a time of major environmental change in Earth history. The Ediacaran period (635–541 Ma), the uppermost division of Precambrian time, is characterized by the remarkable Shuram excursion (largest C isotope negative excursion), a deep ocean water oxidation event, and Ediacaran biota. The Nafun Group of Oman provides a well-preserved and mostly continuous section of an Ediacaran succession. Based on geochemical data from the Nafun Group, the Shuram excursion (SE) and deep ocean oxidation hypotheses were proposed. Now, we sampled this section at high stratigraphic resolution, and present here the petrographical and geochemical analysis of the Khufai, Shuram and Buah Formations. The major and trace element analysis of shales from the Shuram Formation indicates that northern Oman was an active continental margin environment in Neoproterozoic times. The provenance of the Shuram Formation was primarily mafic and intermediate igneous rocks. With the unsteady tectonic setting, the development of the Nafun Group was influenced by hydrothermal supply and volcaniclastic input. Based on the V/Cr and U/Th ratio of the samples from the Nafun Group, our study reveals the transition of the ocean water redox environment, which is connected to the rise and fall of the Ediacaran biota. Our study constrains the tectonic setting of northern Oman and the petrography and geochemical data from the Nafun Group for the hydrothermal and volcaniclastic supply. Thus, our study acknowledges more factors for the explanation of the Ediacaran conundrums.

scholarly journals Tempo-spatial variation of the late Mesozoic volcanism in Southeast China testing the western Paleo-Pacific Plate subduction models

2019 ◽  
Author(s):  
Xianghui Li ◽  
Xianghui Li ◽  
Jingyu Wang ◽  
Chaokai Zhang ◽  
Yin Wang ◽  
...  
Keyword(s):  
Pacific Plate ◽  
Published Data ◽  
Dynamical Process ◽  
Tectonic Zone ◽  
Southeast China ◽  
Late Mesozoic ◽  
Rock Samples ◽  
Lithostratigraphic Units ◽  
Extrusive Rock ◽  
Intensive Group

Abstract. The westward subduction of Paleo-Pacific plate (PPP) played a governing role in tectonic evolution of East Asia. Although various PPP subduction models have been proposed, the subduction age and dynamical process of the PPP remain controversial. In this study, we investigate the geochronology of extrusive rocks and tempo-spatial variations of the late Mesozoic volcanism in Southeast China. We reported zircon U-Pb ages of new 48 extrusive rock samples in the Shi-Hang tectonic zone. Together with the published data, ages of ~ 300 rock samples from ~ 40 lithostratigraphic units were compiled, potentially documenting a relatively complete history and spatial distribution of the late Mesozoic volcanism in Southeast China. The results show that the extrusive rocks spanned ~ 95 Myr (177–82 Ma), but dominantly ~ 70 Myr (160–90 Ma), with two main age populations of 145–125 Ma and 105–95 Ma. We propose that these ages represent the intervals of the Yanshanian volcanism in Southeast China and the western subduction of the PPP, within which two intensive volcanic eruptional pulses happened. Spatially, the age geographic pattern of extrusive rocks is both the oldest and youngest age clusters occurring in the CZ and the younger intensive group in the SHTB, indicating that the late Mesozoic volcanism migrated northwestly from the coast to the inland prior to ~ 145 Ma and subsequently retreated southeastly back to the coast. This migration pattern is interpreted to result from a northwestward subduction followed by a southeastward rollback or retreat of the PPP.

scholarly journals Singularity Analysis of Volcanic Ages and Implications for Tectonic Setting in the Mesozoic, Great Xing’an Range, Northeast China

Minerals ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 419
Author(s):  
Zhu ◽  
Cheng
Keyword(s):  
Tectonic Setting ◽  
Singularity Analysis ◽  
Pacific Plate ◽  
Late Mesozoic ◽  
Plate Movement ◽  
Geological Processes ◽  
The Pacific ◽  
Slab Rollback ◽  
Slab Breakoff ◽  
Great Xing’An Range

Frequency distribution of zircon U–Pb ages has been commonly utilized to interpret the age of a magmatic event. Anomalies in age peaks are related to plate movement caused by mantle convection during the formation of supercontinents and continent crust growth. In this paper, a singularity analysis method (frequency anomalies) is used to analyze a dataset (n = 823, discordance lower than 10%) of zircon U–Pb ages from the Great Xing’an Range (GXR), in order to characterize the causal relationship between age transitions and Pacific Plate subduction. The numberage plot result shows that there is a peak around at 125 Ma, and the log–log plot reveals that there are two transitional ages (knee points) at 125 Ma and 145 Ma. The age densities of the peak at 125 Ma and the transition at 145 Ma can both be fitted by power law functions, which indicate transitional ages have the characteristic of singularity. Combined with the subduction geological background in the late Mesozoic, the possible singularity mechanisms corresponding to the age peak at 125 Ma and the transition at 145 Ma are slab rollback and slab breakoff of the Pacific Plate, which is consistent with conclusions from geology and geochemistry. This result suggests that singularity analysis can be used as a new method to quantitatively characterize volcanic activities and tectonic setting in geological processes.

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.

Lower Cretaceous alkali feldspar granites in the central part of the Great Xing’an Range, northeastern China: chronology, geochemistry and tectonic implications

2014 ◽  
Vol 152 (3) ◽  
pp. 383-399 ◽  
Author(s):  
DEXIN TIAN ◽  
WENCHUN GE ◽  
HAO YANG ◽  
GUOCHUN ZHAO ◽  
YANLONG ZHANG
Keyword(s):  
Lower Cretaceous ◽  
Tectonic Setting ◽  
Alkali Feldspar ◽  
Pacific Plate ◽  
Northeastern China ◽  
Formation Time ◽  
Granitic Rocks ◽  
Geochemical Data ◽  
Regional Geology ◽  
Great Xing’An Range

AbstractThe Mingshui–Jilasitai–Suolun area, located in the central part of the Great Xing’an Range, is characterized by large volumes of alkali feldspar granites. However, the formation time and tectonic setting of these rocks remains controversial owing to a lack of precise geochronological and detailed geochemical data. In this paper, we report new SIMS U–Pb zircon ages and mineralogical, petrographical and geochemical data for Lower Cretaceous alkali feldspar granites from the Mingshui–Jilasitai–Suolun area. The SIMS zircon dating results indicate that these granites formed at 133.6–135.9 Ma. The mineralogical, petrographical and geochemical data show that these granitic rocks belong to highly fractionated I-type granites. Combined with the regional geology data, we propose that the formation of the Lower Cretaceous alkali feldspar granitic rocks was related to an extension induced by delamination of the lithosphere that arose from subduction of the Palaeo-Pacific plate.

Geochemical evidence for the volcanic arc tectonic setting of the Dhanjori volcanics, Singhbhum craton, eastern India

1992 ◽  
Vol 129 (3) ◽  
pp. 337-348 ◽  
Author(s):  
Shabber H. Alvi ◽  
M. Raza
Keyword(s):  
Oceanic Crust ◽  
Continental Margin ◽  
Tectonic Setting ◽  
Geochemical Data ◽  
Chemical Characteristics ◽  
Eastern India ◽  
Volcanic Arc ◽  
Plate Convergence ◽  
Singhbhum Craton ◽  
Geological Information

AbstractGeochemical data on the Dhanjori volcanics of the Singhbhum craton indicate that they range from basalt to andesite and show an iron-enrichment trend. Various chemical characteristics suggest that they are differentiated along the trend similar to that of orogenic suites and have a strong affinity with island arc tholeiites. The field relationships as well as other geological information also support this conclusion and indicate their eruption on a thin continental margin. It is inferred that the Dhanjori volcanics were probably erupted as a result of plate convergence in northern Singhbhum with subduction of oceanic crust below the Singhbhum craton.

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