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 Temporospatial variation in the late Mesozoic volcanism in southeast China

Solid Earth ◽  
2019 ◽  
Vol 10 (6) ◽  
pp. 2089-2101
Author(s):  
Xianghui Li ◽  
Yongxiang Li ◽  
Jingyu Wang ◽  
Chaokai Zhang ◽  
Yin Wang ◽  
...  
Keyword(s):  
Pacific Plate ◽  
Published Data ◽  
Dynamical Process ◽  
Late Mesozoic ◽  
Magmatic Arc ◽  
Rock Samples ◽  
Lithostratigraphic Units ◽  
Back Arc ◽  
Tectonic Belt ◽  
Se China

Abstract. The magmatism (including volcanism) in East Asia (or China) could provide key clues and age constraints for the subduction and dynamical process of the Paleo-Pacific Plate. Although many absolute isotope ages of extrusive rocks have been published in the 1980s–2000s, large uncertainties and large errors prevent the magmatism in southeast (SE) China from being well understood. In this study, we investigate the zircon geochronology of extrusive rocks and temporospatial variations in the late Mesozoic volcanism in SE China. We reported zircon U–Pb ages of new 48 extrusive rock samples in the Shi-Hang tectonic belt. Together with the published data in the past decade, ages of 291 rock samples from ∼40 lithostratigraphic units were compiled, potentially documenting a relatively complete history and spatial distribution of the late Mesozoic volcanism in SE China. The results show that the extrusive rocks spanned ∼95 Myr (177–82 Ma), but dominantly ∼70 Myr (160–90 Ma), within which the volcanism in the early Early Cretaceous (145–125 Ma) was the most intensive and widespread eruption. We propose that these ages represent the intervals of the Yanshanian volcanism in SE China. Spatially, the age geographic pattern of extrusive rocks shows that both the oldest and youngest age clusters occur in the coastal magmatic arc (eastern Zhejiang and Fujian), and the most intensive and widespread age group (145–125 Ma) occurs in a back arc or rifting basin (eastern Jiangxi, central Zhejiang, and northern Guangdong), implying that the late Mesozoic volcanism migrated northwest and subsequently retreated southeast. This volcanic migration pattern may imply that the Paleo-Pacific Plate subducted northwestward and the roll-back subduction did not begin until the Aptian (∼125 Ma) of the mid-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

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.

Rifting and subduction records of the Paleo–Tethys in North Laos: Constraints from Late Paleozoic mafic and plagiogranitic magmatism along the Song Ma tectonic zone

2020 ◽  
Vol 133 (1-2) ◽  
pp. 212-232 ◽  
Author(s):  
Yuzhi Zhang ◽  
Xue Yang ◽  
Yuejun Wang ◽  
Xin Qian ◽  
Yukun Wang ◽  
...  
Keyword(s):  
South China ◽  
Southwest China ◽  
Hainan Island ◽  
Suture Zone ◽  
Published Data ◽  
Tectonic Zone ◽  
Group 3 ◽  
Group 2 ◽  
Subduction Setting ◽  
Group 1

Abstract In Southeast Asia, the Jinshajiang–Ailaoshan suture in Southwest China and the Song Ma zone in Vietnam were generally accepted as the amalgamation boundary of the South China and Simao/Indochina blocks. However, the tectonic location of the Paleotethyan suture in North Laos and its tectonic affinity remain ambiguous. To address this issue, we present the geochemical and geochronological data of a set of mafic and plagiogranitic rocks along the Song Ma suture zone in North Laos. Three groups of rocks with distinctive petrological, geochronological, and geochemical signatures were identified. The ca. 370 Ma Group 1 plagioclase amphibolite was preserved as xenoliths in the ca. 260 Ma granitoids. It exhibits a normal mid–oceanic–ridge basalt (N–MORB)-like, multi-elemental pattern with highly positive εNd(t) (+3.3 to +10.7) and εHf(t) (+6.68 to +7.41) values and low δ18O values (5.3‰−5.5‰), that are interpreted as products of the Late Devonian − earliest Carboniferous continental rift setting. The ca. 270 Ma Group 2 gabbro/diabase–diorite exhibits arc-like geochemical affinity with the εNd(t), εHf(t), and δ18O values of –5.85 to –3.76, –3.8 to +3.2, and 6.6‰–7.6‰, respectively. It is derived from the metasomatized wedge. The ca. 260 Ma Group 3 plagiogranite shows Nb-Ta and Ti negative anomalies and positive εNd(t) (+3.21 to +4.21), εHf(t) (+8.4 to +13.6), and δ18O (5.9‰−6.8‰) values, which are indicative of its derivation from mafic oceanic crust in a subduction setting. In combination with the published data, these results support the development of the Carboniferous–Permian Paleotethyan branch in North Laos, which represents the tectonic location of the Song Ma suture zone that spatially connects the Jinshajiang–Ailaoshan suture zone in Southwest China and the Chenxing–Bangxi suture zone in Hainan Island, South China.

Oxygen–carbon isotope composition of Middle Jurassic–Cretaceous molluscs from the Saratov–Samara Volga region and main climate trends in the Russian Platform–Caucasus

2019 ◽  
Vol 498 (1) ◽  
pp. 101-127 ◽  
Author(s):  
Yuri D. Zakharov ◽  
Vladimir B. Seltser ◽  
Mikheil V. Kakabadze ◽  
Olga P. Smyshlyaeva ◽  
Peter P. Safronov
Keyword(s):  
Carbon Isotope ◽  
Middle Jurassic ◽  
Isotope Composition ◽  
Russian Platform ◽  
Volga Region ◽  
Published Data ◽  
Climate Trends ◽  
Late Mesozoic ◽  
Oxygen And Carbon Isotope ◽  
Epipelagic Zone

AbstractOxygen and carbon isotope data from well-preserved mollusc shells and belemnite rostra are presented from the Jurassic (Bathonian, Callovian and Tithonian) and Cretaceous (Aptian, Turonian, Campanian and Maastrichtian) of the Saratov–Samara Volga region, Russia. New data provide information on the resulting trends in palaeoclimate and in palaeoceanography and palaeoecology in the late Mesozoic. Palaeotemperatures calculated from Jurassic–Cretaceous benthic (bivalves and gastropods) and semi-pelagic (ammonites) molluscs are markedly higher than those calculated from pelagic belemnites using oxygen isotopes. This is probably due to various mollusc groups of the Saratov–Samara area inhabiting different depths in the marine basins (e.g. epipelagic v. mesopelagic). Our isotope records, combined with a review of previously published data from shallow-water fossils from the Saratov–Samara area and adjacent regions permits us to infer temperature trends for the epipelagic zone from the Middle Jurassic to Cretaceous in the Russian Platform–Caucasus area. The Jurassic–Cretaceous belemnites from the Russian Platform and the Caucasus have a lower δ13C signature than the contemporaneous brachiopods, bivalves and ammonites.

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