Late Paleozoic Paleoposition of the Tengchong Block of Southwest China in Gondwana and its implication for the tectonic evolution of Tethys Ocean

Abstract

<p>Decoding the tectonic affinity and correlation of the Tengchong Block with ambient blocks during Late Paleozoic times is crucial to specifically reconstructing their paleogeographic positions in Eastern <a href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/gondwana" title="Learn more about Gondwana from ScienceDirect's AI-generated Topic Pages">Gondwana</a> and understanding the <a href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/tectonic-evolution" title="Learn more about tectonic evolution from ScienceDirect's AI-generated Topic Pages">tectonic evolution</a> of the Meso- and Neo-Tethys in Southeast Asia. Here we present new U<img src="https://sdfestaticassets-us-east-1.sciencedirectassets.com/shared-assets/55/entities/sbnd.gif" alt="single bond">Pb dating results of detrital <a href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/zircon" title="Learn more about zircons from ScienceDirect's AI-generated Topic Pages">zircons</a> from the Carboniferous-Permian Menghong and Gaoligong groups in the Tengchong Block. The youngest magmatic <a href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/zircon" title="Learn more about zircons from ScienceDirect's AI-generated Topic Pages">zircons</a> from the Gaoligong Group showing a weighted mean age of 306.4 Ma, further corroborate that the Gaoligong Group is not the <a href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/precambrian" title="Learn more about Precambrian from ScienceDirect's AI-generated Topic Pages">Precambrian</a> basement but a suite of tectonic complexes including the Late Paleozoic sediments. A compilation of our new results and previously published detrital zircon U<img src="https://sdfestaticassets-us-east-1.sciencedirectassets.com/shared-assets/55/entities/sbnd.gif" alt="single bond">Pb ages for the Carboniferous-Permian sediments in the Tengchong Block show a main age group of 600–400 Ma (peak at 510 Ma) and two subordinate groups of 990–900 Ma (peak at 960 Ma) and 1100–1000 Ma (peak at 1035–1095 Ma). The detrital provenance of the main age group at 600–400 Ma was dominantly derived from the Early Paleozoic orogens on the northern margin of East <a href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/gondwana" title="Learn more about Gondwana from ScienceDirect's AI-generated Topic Pages">Gondwana</a> and partly from the Kuunga Orogen to the southeast of India, while the 990–900 Ma and 1100–1000 Ma components were sourced from the Rayner-Eastern Ghats province between India and <a href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/antarctic-region" title="Learn more about Antarctica from ScienceDirect's AI-generated Topic Pages">Antarctica</a> blocks and the Pinjarra Orogen between the Indo-Antarctica and Australo-Antarctica blocks, respectively. By comparison and analysis of the detrital zircon age spectra, stratigraphy, <a href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/sedimentology" title="Learn more about sedimentology from ScienceDirect's AI-generated Topic Pages">sedimentology</a>, and faunal evidence of the Carboniferous-Permian sediments in the Southeast Asian blocks, we further clarify the tectonic correlation of the Tengchong Block with ambient blocks in the Late Paleozoic and reconstruct their paleoposition in East Gondwana. The Tengchong and Irrawaddy blocks were connected closely and formed a united continental block (Tengchong-Irrawaddy Block: TIB), while the South Qiangtang and Baoshan blocks along with the Shan Plateau were linked together and constituted the Sibuma Block during Late Paleozoic times. The TIB was linked with the <a href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/himalayas" title="Learn more about Himalaya from ScienceDirect's AI-generated Topic Pages">Himalaya</a> <a href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/terrane" title="Learn more about terrane from ScienceDirect's AI-generated Topic Pages">terrane</a> on the northeastern margin of Indian Gondwana, whereas the Sibuma Block had rifted away from northern Indian Gondwana at that time. Our new paleogeographic reconstruction illustrates that the Bangong-Nuijiang Meso-Tethys suture within the <a href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/tibetan-plateau" title="Learn more about Tibetan Plateau from ScienceDirect's AI-generated Topic Pages">Tibetan Plateau</a> extends southward through the Gaoligong Shear Zone in Western Yunnan of China and then into the Medial Myanmar Suture Zone in East Myanmar. The Myitkyina-Tagaung <a href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/ophiolite" title="Learn more about ophiolite from ScienceDirect's AI-generated Topic Pages">ophiolite</a> belt represents the remnants of the Neo-Tethys Ocean.<br></p>