Radiolarian age constraints on Mesotethyan ocean evolution, and their implications for development of the Bangong–Nujiang suture, Tibet

Baxter, A.T.; Aitchison, Jonathan C.; Zyabrev, S. V.

doi:10.1144/0016-76492008-128

Cited by 139 publications

(70 citation statements)

References 34 publications

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“…The group consists of dark shales, siltstones, fine-to medium-grained sandstones with olistoliths, limestone lenses and quartzite. The whole sequence of sandy foreshore or shore facies sediments is possibly related to the earliest stages of basin subsidence in the southern Qiangtang realm during Early Jurassic extension (Duan et al, 2009;Schneider et al, 2003) and Meso-Tethys formation (Baxter et al, 2009). Tertiary (possible even Late Cretaceous) to recent terrestrial sediments, mostly conglomerates, cover the area in scattered, usually fault-bounded basins (Kapp et al, 2005).…”

Section: Post-collision Stratigraphy and Lithologiesmentioning

confidence: 99%

“…Jurassic the deep-water flysch sediments (J 1−2 s) cover all the older units in the southern SQT. These are thought to represent the opening of the Bangong-Nujiang suture zone (Schneider et al, 2003;Baxter et al, 2009). It is not known whether Jurassic sediments once covered the whole Qiangtang terrane or they were never deposited there.…”

Section: Jurassic (200-170 Ma)mentioning

confidence: 99%

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Tectonic evolution and high-pressure rock exhumation in the Qiangtang terrane, central Tibet

et al. 2015

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Abstract. Conflicting interpretations of the > 500 km long, east-west-trending Qiangtang metamorphic belt have led to very different and contradicting models for the PermoTriassic tectonic evolution of central Tibet. We define two metamorphic events, one that only affected pre-Ordovician basement rocks and one subduction-related Triassic highpressure metamorphism event. Detailed mapping and structural analysis allowed us to define three main units that were juxtaposed due to collision of the north and south Qiangtang terranes after closure of the Ordovician-Triassic ocean that separated them. The base is formed by the Precambrian-Carboniferous basement, followed by nonmetamorphic ophiolitic mélange containing mafic rocks that range in age from the Ordovician to Middle Triassic. The top of the sequence is formed by strongly deformed sedimentary mélange that contains up to > 10 km size rafts of both unmetamorphosed Permian sediments and highpressure blueschists. We propose that the high-pressure rocks were exhumed from underneath the south Qiangtang terrane in an extensional setting caused by the pull of the northward subducting slab of the Shuanghu-Tethys. Highpressure rocks, sedimentary mélange and margin sediments were thrust on top of the ophiolitic mélange that was scraped off the subducting plate. Both units were subsequently thrust on top of the south Qiantang terrane continental basement. Onset of Late Triassic sedimentation marked the end of the amalgamation of both Qiangtang terranes and the beginning of spreading between Qiantang and north Lhasa to the south, leading to the deposition of thick flysch deposits in the Jurassic.

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Section: Post-collision Stratigraphy and Lithologiesmentioning

confidence: 99%

Section: Jurassic (200-170 Ma)mentioning

confidence: 99%

Tectonic evolution and high-pressure rock exhumation in the Qiangtang terrane, central Tibet

et al. 2015

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“…Ninomiya et al [15,17] suggested the high correlation of the detected ultramafic rocks using ASTER-TIR data with the ones described in the published ophiolite map along the middle Yarlung Zangbo river [44] for the local area south of Xigaze (indicated in Figure 8), but this study suggests the agreement within the entire region of the map. Likewise, the good agreement in the mapping results for the ultramafic rocks of Yongzhu-Guomangco section [39,40], Dong Tso section [41] and Lagkor Tso section [41,42] is suggested.…”

Section: Geological Interpretation On the Resultsmentioning

confidence: 71%

“…The most important geological features targeted in this study include the ophiolite belts appearing at the surface along the sutures of the blocks, the quartzose and carbonite sedimentary rocks deposited as the accretion wedges associated with the subduction of the oceanic plate beneath the continental plate, the granitic rocks intruded with the island arc geological setting, and the distributions of the sulfate layers as the geological evidences of the neo-Tethys environment. The field geological studies so far (e.g., [36][37][38][39][40][41][42][43]) have revealed the distribution of the target lithological features at some limited local areas in the Tibetan Plateau. However, these terranes and suture zones are poorly characterized in central Tibet, with a >1000-km-long and up to 500-km-wide tectonic belt, where the field geological surveys have not yet accomplished well for the most part of the region because this area is remote and inaccessible (Figure 1).…”

Section: Study Areamentioning

confidence: 99%

Regional Lithological Mapping Using ASTER-TIR Data: Preliminary Case Study for the Tibetan Plateau and the Surrounding Area

Ninomiya

2016

Preprint

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Abstract:The mineralogical indices; the Quartz Index (QI), Carbonate Index (CI) and Mafic Index (MI) for ASTER multispectral thermal infrared (TIR) data were applied to various geological materials for regional lithological mapping on the Tibetan Plateau. Many lithological and structural features are not currently well understood in the central Tibetan Plateau, including the distribution of mafic-ultramafic rocks related to the suture zones, the quartzose and carbonate sedimentary rocks accreted to the Eurasian continent, and sulfate layers related to the Tethys and neo-Tethys geological setting. These rock types can now be mapped with the interpretation of the processed ASTER TIR images described in this paper. A methodology is described for the processing of ASTER TIR data applied to a very wide region of the Tibetan Plateau. The geometrical and radiometric performance of the processed images is discussed, and the advantages of using ortho-rectified data are shown. The challenges of using ASTER data with small footprint in addition to selecting an appropriate subset of scenes are also examined. ASTER scenes possess a narrow swath width when compared to LANDSAT data (60 km vs. 185 km respectively). Furthermore, the ASTER data archive is vast consisting of approximately 3 million images. These details can present an added level of complexity during an image processing workflow. Finally, geological interpretations made on the maps of the indices are compared with prior geological field studies. The results from the investigations suggest that the indices perform well in the classification of quartzose rocks based on the carbonate and the mafic mineral content, in addition to the granitic rocks based on the feldspar content.

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“…This understanding could provide critical background information for interpreting the origin and emplacement mechanism of various types of ophiolites reported from the BNSZ, because previous studies were mostly petrology-and geochronology-oriented [18][19][20][21][22][23].…”

Section: Mappable Features Of the Mg And Tectonic Implicationsmentioning

confidence: 99%

Mapping Lithologic Components of Ophiolitic Mélanges Based on ASTER Spectral Analysis: A Case Study from the Bangong-Nujiang Suture Zone (Tibet, China)

Zhang

Zeng

2018

IJGI

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ASTER (Advanced Spaceborne Thermal Emission and Reflection) satellite imagery is useful in assisting lithologic mapping and, however, its effectiveness is yet to be evaluated for lithologic complex such as tectonic mélange. The Mugagangri Group (MG), the signature unit of the Bangong-Nujiang suture zone (BNSZ), Tibet and consisting of ophiolitic mélanges, was previously mapped as a single unit due to its poorly-described internal structures and an informative map with refined lithologic subdivision is needed for future petrologic and tectonic studies. In this paper, based on a combination of field work and ASTER data analysis, the MG is mapped as five subunits according to our newly-proposed lithologic subdivision scheme. In particular, we apply a data-processing sequence to first analyze the TIR band ratios to reveal approximate distribution of carbonates and silicate-dominated lithologies and then the VNIR/SWIR band ratios and false color images to differentiate the lithologic units and delineate their boundaries. The generalized procedures of ASTER data processing and lithologic mapping are applicable for future studies in not only the BNSZ but also other Tibetan ranges. Moreover, the mapping result is consistent with that the MG represents an accretionary complex accreted to the south Qiangtang margin as a result of northward-subduction of the Bangong-Nujiang oceanic crust.

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Radiolarian age constraints on Mesotethyan ocean evolution, and their implications for development of the Bangong–Nujiang suture, Tibet

Cited by 139 publications

References 34 publications

Tectonic evolution and high-pressure rock exhumation in the Qiangtang terrane, central Tibet

Tectonic evolution and high-pressure rock exhumation in the Qiangtang terrane, central Tibet

Regional Lithological Mapping Using ASTER-TIR Data: Preliminary Case Study for the Tibetan Plateau and the Surrounding Area

Mapping Lithologic Components of Ophiolitic Mélanges Based on ASTER Spectral Analysis: A Case Study from the Bangong-Nujiang Suture Zone (Tibet, China)

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