Northernmost paleo-tethyan oceanic basin in Tibet: Geochronological evidence from40Ar/39Ar age dating of Dur’ngoi ophiolite

Chen, Liang; Sun, Yong; Pei, Xianzhi; Gao, Ming; Feng, Tao; Zhang, Zhongqing; Chen, Wen

doi:10.1007/bf02900603

Cited by 73 publications

(32 citation statements)

References 2 publications

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“…Hence, using them to discuss geochemistry of the primary rocks undergoing greenschist metamorphism in this area can be safe and reliable. In fact, the previous studies on geochemistry, tectonic discrimination and geochronology (Ar/Ar method) of the ophiolites have proved that the metamorphic effects are limited [11,13,15] .…”

Section: Geochemistrymentioning

confidence: 98%

“…Bian et al [11] identified early-late Carboniferous siliceous radiolarian from silicalites in the Buqingshan ophiolites. Chen et al [15] determined a whole-rock 40 Ar/ 39 Ar plateau age of 345.3 ± 7.9 Ma from basalts in the Dur'ngoi ophiolites. Later, Zhang et al [16] reported the discovery of early Permian siliceous radiolarian in the Buqingshan ophiolite mélange.…”

Section: Regional Geologymentioning

confidence: 99%

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Geochemistry and spatial distribution of OIB and MORB in A’nyemaqen ophiolite zone: Evidence of Majixueshan ancient ridge-centered hotspot

et al. 2007

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The mafic volcanic association is made up of OIB, E-MORB and N-MORB in the A'nyemaqen Paleozoicophiolites. Compared with the same type rocks in the world, the mafic rocks generally display lower Nb/U and Ce/Pb ratios and some have Nb depletion and Pb enrichment. The OIB are LREE-enriched with (La/Yb) N =5-20, N-MORB are LREE-depleted with (La/Yb) N = 0.41-0.5. The OIB are featured by incompatible element enrichment and the N-MORB are obviously depleted with some metasomatic effect, and E-MORB are geochemically intermediated. These rocks are distributed around the Majixueshan OIB and gabbros in a thickness greater than a thousand meters and transitionally change along the ophiolite extension in a west-east direction, showing a symmetric distribution pattern as centered by the Majixueshan OIB, that is, from N-MORB, OIB and E-MORB association in the Dur'ngoi area to OIB in the Majixueshan area and then to N-MORB, OIB and E-MORB assemblage again in the Buqingshan area. By consideration of the rock association, the rock spatial distribution and the thickness of the mafic rocks in the Majixueshan, coupled with the metasomatic relationship between the OIB and MORB sources, it can be argued that the Majixueshan probably corresponds to an ancient hotspot or an ocean island formed by mantle plume on the A'nyemaqeh ocean ridge, that is the ridge-centered hotspot, tectonically similar to the present-day Iceland hotspot.A'nyemaqen ophiolite zone, OIB, N-MORB and E-MORB association, spatial distribution, Majixueshan ridge-centered hotspot, metasomatism, mantle plume Coexistence of normal mid-ocean-ridge basalts (N-MORB), enriched mid-ocean-ridge basalts (E-MORB) and ocean island basalts (OIB) in the certain tectonic setting has drawn extensive attention and strong interest. Iceland in the North Atlantic Ocean has become a well-known example for the phenomenon. The phenomenon has been thought to be a result of superposition of a hotspot on a ridge (ridge-centered hotspot) [1] or an oceanic island on a ridge (ridge-centered island) [2] or a mantle plume on a ridge (plume on-ridge) [3] , and hotspot-ridge interaction or plume-ridge interaction [4,5] . The spatial superposition and materials interaction between a ridge and a hotspot or an ocean island or a plume cause anomalies of geochemistry, topography, crustal structure, gravity, seismic velocity and bathymetry in the area surrounding a ridge-hotspot [1] .Recent studies have indicated that the coexistence not only occurs in a modern environment like Iceland, but also can be traced into ophiolite zones representing preserved oceanic crust in continental orogenic belts. Hou et al. [6,7] , according to the coexistence of OIB, N-MORB and T-MORB and their specific configuration in space, proposed a paleo-Tethyan mantle plume model to inter-

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Section: Geochemistrymentioning

confidence: 98%

Section: Regional Geologymentioning

confidence: 99%

Geochemistry and spatial distribution of OIB and MORB in A’nyemaqen ophiolite zone: Evidence of Majixueshan ancient ridge-centered hotspot

et al. 2007

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“…identified early Late Carboniferous siliceous radiolarian from silicalites in the Buqingshan ophiolites. Chen et al [9] determined a whole-rock 40 Ar/ 39 Ar plateau age of 345.3 ± 7.9 Ma from basalts in the Dur'ngoi ophiolites. Zhang et al [10] reported the discovery of early Permian siliceous radiolarian in the Buqingshan ophiolite mélange.…”

Section: A'nyêmaqên Ophiolite Zonementioning

confidence: 99%

“…The triple-junction first rifted on the Precambrian and Caledonian continental basement, which was marked by the Devonian diabase dykes [12] . And then, during the late Devonian and early Carboniferous, around the Majixueshan area, the oceanic crust occurred in the eastern and western arms of the junction, also in the southern potion of the KS zone [6][7][8][9]14] that is a failed northern arm of the junction and the main section is the continental rift setting. In terms of tectonics, the formation of the triple-junction is an expression of hotspot activities that initiated the continental breakup and continent-ocean transformation.…”

Section: Majixueshan Triple-junctionmentioning

confidence: 99%

Geochemistry and spatial distribution of late-Paleozoic mafic volcanic rocks in the surrounding areas of the Gonghe Basin: Implications for Majixueshan triple-junction and east Paleotethyan archipelagic ocean

Guo

Zhang

Sun

et al. 2007

Sci. China Ser. D-Earth Sci.

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The late-Paleozoic mafic volcanic rocks occurring in the surrounding areas of the Gonghe basin are distributed in the A'nyêmaqên ophiolite zone, Zongwulong tectonic zone and Kuhai-Saishitang volcanic zone. The mafic volcanics in the A'nyêmaqên zone formed an ancient ridge-centered hotspot around the Majixueshan OIB, the Kuhai-Saishitang mafic rocks consist of E-MORB and continental rift basalts and the Zongwulong volcanic rocks are enriched N-MORB. The regionally low Nb/U and Ce/Pb ratios reflect the influence of the OIB material on the mafic magma source. From geochemistry, spatial distribution and tectonic relationship of the mafic rocks, an ancient triple-junction centered at the Majixueshan can be inferred. The existence of the Kuhai-Saishitang aulacogen may have provided a tectonic channel for the Majixueshan OIB materials metasomatizing the magma source for the Zongwulong rocks. The formation of the triple-junction and the rifting of the Zongwulong zone have separated the orogens and massifs in the region.

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“…To the south, at Dur'ngoi, in the eastern part of the southern east Kunlun (the A'nyêmaqên area), Carboniferous ages were reported (whole-rock 40 Ar/ 39 Ar plateau age of 345.3±7.9 Ma [18] and zircon SHRIMP U-Pb age of 308.2±4.9 Ma for basalts [19] ) but no Early Paleozoic ages. Thus some researchers suggest that the southern east Kunlun tectonic belt is comparable to the Mianlüe tectonic belt in the Qinling orogenic belt, both belonging to the Paleo-Tethys tectonic system at the northwestern margin of the Yangtze Plate [20] .…”

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confidence: 99%

Zircon SHRIMP U-Pb ages and trace element geochemistry of the Kuhai gabbro and the Dur’ngoi diorite in the southern east Kunlun tectonic belt, Qinghai, Western China and their geological implications

Guo

et al. 2007

Sci. China Ser. D-Earth Sci.

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Timing of the intermediate-basic igneous rocks developed in the area of Kuhai-A'nyêmaqên along the southern east Kunlun tectonic belt is a controversial issue. This paper presents new zircon SHRIMPU-Pb dating data for igneous zircons from the Kuhai gabbro and the Dur'ngoi diorite in the Kuhai-A'nyemaqen tectonic belt, which are 555±9 Ma and 493±6 Ma, respectively. The trace element geochemical features of the Kuhai gabbro and the Dur'ngoi diorite are similar to those of ocean island basalts (OIB) and island arc basalts (IAB), respectively. Thus, the Kuhai gabbro with the age of 555±9 Ma and OIB geochemical features is similar to the Yushigou oceanic ophiolite in the North Qilian orogen, whereas the Dur'ngoi diorite with the age of 493±6 Ma and IAB geochemical features is similar to the island arc volcanic rocks developed in the north Qaidam. The Late Neoproterozoic to Early Ordovician ophiolite complex in the area of Kuhai-A'nyêmaqên suggests that the southern margin of the "Qilian-Qaidam-Kunlun" archipelagic ocean in this period was located in the southern east Kunlun tectonic belt. Therefore, the southern east Kunlun tectonic belt in the early Paleozoic is not comparable to the Mianlüe tectonic belt in the Qinling orogenic belt.

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Northernmost paleo-tethyan oceanic basin in Tibet: Geochronological evidence from40Ar/39Ar age dating of Dur’ngoi ophiolite

Cited by 73 publications

References 2 publications

Geochemistry and spatial distribution of OIB and MORB in A’nyemaqen ophiolite zone: Evidence of Majixueshan ancient ridge-centered hotspot

Geochemistry and spatial distribution of OIB and MORB in A’nyemaqen ophiolite zone: Evidence of Majixueshan ancient ridge-centered hotspot

Geochemistry and spatial distribution of late-Paleozoic mafic volcanic rocks in the surrounding areas of the Gonghe Basin: Implications for Majixueshan triple-junction and east Paleotethyan archipelagic ocean

Zircon SHRIMP U-Pb ages and trace element geochemistry of the Kuhai gabbro and the Dur’ngoi diorite in the southern east Kunlun tectonic belt, Qinghai, Western China and their geological implications

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