Late Paleozoic–Early Mesozoic southward subduction-closure of the Paleo-Asian Ocean: Proof from geochemistry and geochronology of Early Permian–Late Triassic felsic intrusive rocks from North Liaoning, NE China

Lithos ◽  
2019 ◽  
Vol 346-347 ◽  
pp. 105165 ◽  
Author(s):  
Yi Shi ◽  
Zhenghong Liu ◽  
Yongjiang Liu ◽  
Shaoshan Shi ◽  
Minghui Wei ◽  
...  
Keyword(s):  
Late Triassic ◽  
Late Paleozoic ◽  
Early Permian ◽  
Ne China ◽  
Early Mesozoic ◽  
Intrusive Rocks

Early Mesozoic granitoids from SW Vietnam and SE Cambodia – an example of the southeastern extension of the Southeast Asian granite belt

2020 ◽  
Author(s):  
Anh Nong ◽  
Christoph Hauzenberger ◽  
Daniela Gallhofer ◽  
Sang Dinh
Keyword(s):  
Large Scale ◽  
Early Stage ◽  
Tectonic Setting ◽  
Biotite Granite ◽  
Coarse Grained ◽  
Late Triassic ◽  
Late Paleozoic ◽  
Western Boundary ◽  
Early Mesozoic ◽  
Granite Belt

<p>Early Mesozoic magmatism in Indochina and its vicinities in Sundaland (SE Asia) has been usually ascribed to be in connection with one of three approximately coeval tectonic regimes: 1) the Indochina-Sibumasu amalgamation leading to the closure of the Paleotethys during the Late Paleozoic – Early Mesozoic forming the Thai-Malaysia tin-bearing granite belt, 2) the Indochina-South China amalgamation along the northern boundary of Indochina closing another branch of the Paleotethys during Late Paleozoic – Triassic times, and 3) the early stage of an active margin with subduction of the Paleo-Pacific plate during Triassic-Jurassic times.</p><p>Scattered granitic plutons (185–210 Ma) located in southern Cambodia and some islands in southernmost Vietnam are distributed along the N-S Rach Gia-Nam Can fault which is a large-scale fault active during the Early Mesozoic. The studied rocks can be distinguished based on petrological features: weakly foliated biotite-rich granite (Hon Khoai Island, SW Vietnam), biotite-tourmaline-bearing granite (Hon Da Bac Island, SW Vietnam), and coarse-grained biotite granite (Tamao, SE Cambodia). The Honkhoai granites are a range of dark to light coloured granites due to a variation in biotite content and display a foliation. They usually contain amphibole, ilmenite, and monazite. The Hondabac granites comprise dark-colored granodiorites and granites with biotite, tourmaline, ilmenite, apatite, fluorite, epidote, and subordinate titanite. The Tamao granites are mainly composed of biotite aggregates with sporadic muscovite and accessory phases such as ilmenite, apatite, and fluorite.</p><p>Zircon U-Pb ages yield 189 ± 1 to 206 ± 2 Ma for the Honkhoai rocks, 192 ± 1 to 202 ± 1 Ma for the Hondabac rocks, and 189 ± 2 Ma for the Tamao rocks. Apparently, these Late Triassic - Early Jurassic granitoids are chronologically consistent with all three tectonic events. However, geographical and geochemical arguments favor a connection to the Thai-Malaysia tin-bearing granites. Similarities include high silica content and predominantly high-K to calc-alkaline affinities. Trace element composition is characterized by enrichments in Cs, Rb, Th, U, and Pb, and depletion in Ba, Sr, Nb, P, and Ti. All analyzed rock samples show (La/Yb)n values of 4.05–17.27 and negative Eu anomalies (Eu/Eu*=0.15–0.65). The whole-rock and biotite chemistry point to an arc-related tectonic setting for the Hondabac rock, while the Honkhoai and Tamao rocks are ambiguous in the tectonic regime but likely close to syn-collision and within-plate field, respectively. Geobarometry of the Honkhoai rocks using the Al-in-amphibole geobarometer yields crystallization pressure up to 3 kbar.</p><p>We conclude that the studied rocks formed during the closure of the Palaeotethys along the western boundary of the Indochina block, particularly similar to the Thai-Malaysia granite belt. Hence, the Sukhothai-Chantaburi Terrane may be extended southeastward as far as to the Hon Khoai Island (Southernmost Vietnam).</p>

Detrital zircon U–Pb dating of Late Triassic Wenbinshan Formation in southwestern Fujian, South China, and its geological significance

2018 ◽  
Vol 55 (8) ◽  
pp. 980-996 ◽  
Author(s):  
Zhongjie Xu ◽  
Yizhi Lan ◽  
Jintao Kong ◽  
Rihui Cheng ◽  
Liaoliang Wang
Keyword(s):  
South China ◽  
Detrital Zircon ◽  
Coastal Areas ◽  
Late Triassic ◽  
Late Paleozoic ◽  
Age Composition ◽  
Zircon Age ◽  
Early Mesozoic ◽  
Similarities And Differences ◽  
Southwestern Fujian

Based on research of the petrology, geochemistry, and zircon U–Pb dating of detrital rocks in the Late Triassic Wenbinshan Formation in southwestern Fujian, and comparing the detrital zircon ages of Wenbinshan Formation with those of Late Paleozoic – Early Mesozoic main basins in South China, the sedimentary provenance of the Late Triassic in southwestern Fujian and its implications for changes in basin properties are discussed. The research results demonstrate that there is a major age peak at 222 Ma, two subordinate age peaks at 275 Ma and 1851 Ma, and two minor age peaks at 413 Ma and 2447 Ma in the detrital zircon age spectra of the upper samples (YGP–6) of the Wenbinshan Formation, whereas there are two major age peaks at 229 Ma and 1817 Ma and other minor age peaks 265 Ma 309 Ma, 415 Ma, 1968 Ma, and 2435 Ma in the detrital zircon age spectra of the lower samples (YGP–26) of the Wenbinshan Formation. The upper samples contain fewer old detrital zircons than the lower samples, but the upper and lower samples of Wenbinshan Formation are similar in major age composition, which indicates the main provenances of the upper and lower sediments are very similar. The source rocks are mainly sedimentary rocks and their provenances are derived from a source area of recycled orogenic belt and volcanic arc orogenic belt (acidic island arc). The detrital zircon composition of the Wenbinshan Formation is mainly composed of Paleoproterozoic zircon and Late Paleozoic – Early Mesozoic zircon. In the Paleoproterozoic, sedimentary provenances were mainly derived from the Wuyi Massif and partly from northwestern Fujian-southwestern Zhejiang. As for the period of Late Paleozoic – Early Mesozoic, the provenances of the Wenbinshan Formation were derived from magmatic active belts of the Early Indosinian Epoch of northern South China, eastern South China, and the Indosinian Period of northern South China and coastal areas of eastern South China. The similarities and differences between detrital zircon age peaks of the Wenbinshan Formation in southwestern Fujian and that of the main basins in South China during the period of Late Paleozoic – Early Mesozoic indicate that from eastern coastal areas of South China to the north and interior of South China, the age composition of basin sediments has changed from simple to relatively complex, and from young sediments to older sediments. There are similarities and differences in the detrital zircon compositions of the different basins, which can indicate differences in the nature of the basins.

scholarly journals Geochemistry and Zircon U-Pb-Hf Isotopes of Metamorphic Rocks from the Kaiyuan and Hulan Tectonic Mélanges, NE China: Implications for the Tectonic Evolution of the Paleo-Asian and Mudanjiang Oceans

Minerals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 836
Author(s):  
Zuozhen Han ◽  
Jingjing Li ◽  
Zhigang Song ◽  
Guyao Liu ◽  
Wenjian Zhong ◽  
...  
Keyword(s):  
Tectonic Evolution ◽  
Middle Triassic ◽  
Late Triassic ◽  
Metamorphic Rocks ◽  
Late Permian ◽  
Early Permian ◽  
Ne China ◽  
The North ◽  
Tectonic Mélange ◽  
Final Closure

The Late Paleozoic–Early Mesozoic tectonic evolution of the Changchun-Yanji suture (CYS) was mainly associated with the Paleo-Asian and Mudanjiang tectonic regimes. However, the spatial and temporal overprinting and variations of these two regimes remains are still dispute. In order to evaluate this issue, in this contribution, we present new zircon U-Pb ages and a whole-rock geochemical and zircon Hf isotopic dataset on a suite of metamorphic rocks, including gneisses, actinolite schist, leptynites, and biotite schists, from tectonic mélanges in northern Liaoning and central Jilin provinces, NE China. Based on zircon LA-ICP-MS U-Pb dating results, protoliths show wide ranges of aging spectrum, including Paleoproterozoic (2441 Ma), Early Permian (281 Ma), Late Permian (254 Ma), and Late Triassic (230 Ma). The Permian protoliths of leptynites from the Hulan Tectonic Mélange (HLTM) and gneisses from the Kaiyuan Tectonic Mélange (KYTM) exhibit arc-related geochemical signatures, implying that the Paleo-Asian Ocean (PAO) did not close prior to the Late Permian. The Late Triassic protoliths of gneisses from the KYTM, in combination with previously reported coeval igneous rocks along the CYS, comprises a typical bimodal igneous suite in an E–W-trending belt, suggesting a post-orogenic extensional environment. Consequently, we infer that the final closure of the PAO took place during the Early–Middle Triassic. The Early Permian protoliths of biotite schists from the HLTM are alkali basaltic rocks and contain multiple older inherited zircons, which, in conjunction with the geochemical features of the rocks, indicate that they were generated in a continental rift related to the initial opening of the Mudanjiang Ocean (MO). Data from this contribution and previous studies lead us to conclude that the MO probably opened during the Middle Triassic, due to the north–south trending compression caused by the final closure of the PAO.

Local and global abundance associated with extinction risk in late Paleozoic and early Mesozoic gastropods

Paleobiology ◽  
2011 ◽  
Vol 37 (4) ◽  
pp. 616-632 ◽  
Author(s):  
Jonathan L. Payne ◽  
Sarah Truebe ◽  
Alexander Nützel ◽  
Ellen T. Chang
Keyword(s):  
Regression Analysis ◽  
Population Size ◽  
Extinction Risk ◽  
Geographic Range ◽  
Early Jurassic ◽  
Occurrence Frequency ◽  
Late Paleozoic ◽  
Early Permian ◽  
Early Mesozoic ◽  
Minimum Criteria

Ecological theory predicts an inverse association between population size and extinction risk, but most previous paleontological studies have failed to confirm this relationship. The reasons for this discrepancy between theory and observation remain poorly understood. In this study, we compiled a global database of gastropod occurrences and collection-level abundances spanning the Early Permian through Early Jurassic (Pliensbachian). Globally, the database contains 5469 occurrences of 496 genera and 2156 species from 839 localities. Within the database, 30 collections distributed across seven stages contain at least 75 specimens and ten genera—our minimum criteria for within-collection analysis of extinction selectivity. We use logistic regression analysis, based on global and local measures of population size and stage-level extinction patterns in Early Permian through Early Jurassic marine gastropods, to assess the relationship between abundance and extinction risk. We find that global genus occurrence frequency is inversely associated with extinction risk (i.e., positively associated with survival) in 15 of 16 stages examined, statistically significantly so in five stages. Although correlation between geographic range and occurrence frequency may account for some of this association, results from multivariable regression analysis suggest that the association between occurrence frequency and extinction risk is largely independent of geographic range. Within local assemblages, abundance (number of individuals) is also inversely associated with extinction risk. The strength of association is consistent across time and modes of fossil preservation. Effect strength is poorly constrained, particularly in analyses of local collections. In addition to limited power due to small sample size, this poor constraint may result from confounding by ecological variables not controlled for in the analyses, by taphonomic or collection biases, or from non-monotonic relationships between abundance and extinction risk. Two factors are likely to account for the difference between our results and those of most previous studies. First, many previous studies focused on the end-Cretaceous mass extinction event; the extent to which these results can be generalized to other intervals remains unclear. Second, previous findings of nonselective extinction could result from insufficient statistical power rather than the absence of an underlying effect, because nonselective extinction is generally used as the null hypothesis for statistical convenience. Survivorship patterns in late Paleozoic and early Mesozoic gastropods suggest that abundance has been a more important influence on extinction risk through the Phanerozoic than previously appreciated.

Mineralization characteristics, genetic type and metallogenic time of stratiform ore bodies in Hongtaiping copper polymetallic deposit in Yanbian area, NE China

2020 ◽  
Author(s):  
Yunsheng Ren ◽  
Siyu Lu ◽  
Henan Hou ◽  
Qun Yang
Keyword(s):  
Genetic Type ◽  
Late Triassic ◽  
Late Paleozoic ◽  
Ne China ◽  
Rock Samples ◽  
Polymetallic Deposit ◽  
Ore Body ◽  
Ore Bodies ◽  
Icp Ms ◽  
Isotope Dating

<p>   </p><p>      The Yanbian area in northeast (NE) China is located in the eastern segment of the Central Asian Orogenic Belt. Due to its special tectonic location and complicated geologic evolution history, this area has been taken as a crucial region for studying late Paleozoic and Mesozoic tectonics, magmatism and metallogeny. There are a series of late Paleozoic volcanic-sedimentary formations in Yanbian area which host several copper polymetallic deposits including Hongtaiping in Wangqing area and Dongfengnanshan in Tianbaoshan ore district.</p><ol><li><strong>Rock assembles of ore-hosting volcanic-sedimentary formations </strong></li> </ol><p>     Filed survey and petrography researches indicate rock types in the late Paleozoic ore-hosting volcanic-sedimentary formations within and around the Hongtaiping and Dongfengnanshan deposit, Miaoling Formation, are mainly composed of tuffaceous sandstone, andesitic tuff, rhyolite, andesite, basalt, dacite, sandstone, carbonate, as well as minor silicolite and fluorite. These rock assembles imply the ore-hosting rocks belong to shallow-marine terrigenous sedimentary-volcanic-pyroclastic rock formation.</p><ol><li><strong>Mineralization characteristics and genetic type of stratiform ore bodies in Hongtaiping copper polymetallic deposit </strong></li> </ol><p>      Sixteen ore bodies in Hongtaiping deposit can be classified into two types, the stratiform and vein-type. The major stratiform ore bodies are flat and nearly horizontal, consistent with the Miaoling Formation in occurrence. The largest ore body is 570m long, 50 to 150m wide. The ore in the stratiform ore body is mainly characterized by the banded, lamellar and massive structure. The metal minerals mainly include pyrrhotite, pyrite, chalcopyrite and sphalerite, and most of the metal minerals show allotriomorphic granular and weak metasomatic texture. The microscopic characteristics of the ore show that the boundary between sphalerite and pyrite is relatively flat. According to the ore-hosting rock assembles, some typical alternation and mineralization characteristics, including exhalite in ore-hosting rock series, banded and layered ore bodies, as well as comparisons between the Hongtaiping and some typical VMS-type (e.g. the Laochang in Yunnan Province and the Dabaoshan in Guangdong Province), the Hongtaiping deposit can be classified into the VMS-type.</p><ol><li><strong> Metallogenic time of Hongtaiping copper polymetallic deposit</strong></li> </ol><p>      LA-ICP-MS zircon U-Pb dating of 69 igneous zircon grains in four volcanic clastic rock samples from the ore-hosting Miaoling Formation in the Hongtaiping deposit yields <sup>206</sup>Pb/<sup>238</sup>U ages from 258±8 Ma to 293±10 Ma, and weighted mean age of 268.2±3.3Ma (MSWD=0.42), 273.8±4.7Ma (MSWD=1.3), 268.0±3.2Ma (MSWD=0.66) and 272.4±3.2Ma (MSWD=1.04), respectively. Rb-Sr isotope dating of seven sulfides (one pyrite, one sphalerite, two pyrrhotite and three chalcopyrite) yields the isochron age of 268.3±2.6Ma, which nearly consistent with LA-ICP-MS zircon U-Pb dating results of four ore-hosting volcanic rock samples. Isotope dating results demonstrate the VMS-type stratiform copper polymetallic mineralization in Hongtaiping deposit formed in the early-middle Permian period instead of late Triassic or early Jurassic period.</p><p>Acknowledgments: This work was supported by the National Natural Science Foundation of China (NSFC) (No.41772062)</p>

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