Tectonic Evolution of Southeast Central Asian Orogenic Belt: Evidence from Geochronological Data and Paleontology of the
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ISSN 1674-487X
Tectonic Evolution of Southeast Central Asian Orogenic Belt: Evidence from Geochronological Data and Paleontology of the Early Paleozoic Deposits in Inner Mongolia Shijie Wang
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, Shichao Li *1, 2, Wenjie Li3, Zhongyuan Xu1, Jinfeng Zhang4, Changhai Li1, Qiang Shi1, Yang Liu5, Wenlong Wang5, Qingbin Guan6
1. College of Earth Sciences, Jilin University, Changchun 130061, China 2. Key Laboratory of Mineral Resources Evaluation in Northeast Asia, Ministry of Natural Resources, Changchun 130061, China 3. Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, China 4. School of Earth Sciences, Northeast Petroleum University, Daqing 163318, China 5. Tianjin Center of Geological Survey, China Geological Survey, Tianjin 300170, China 6. Key Lab of Submarine Geosciences and Prospecting Techniques, MOE, Institute for Advanced Ocean Study, College of Marine Geosciences, Ocean University of China, Qingdao 266237, China Shijie Wang: https://orcid.org/0000-0003-4568-1906; Shichao Li: https://orcid.org/0000-0003-3928-2132 ABSTRACT: In this study, we present detrital zircon U-Pb dating and paleontological data for the newly identified Ayadeng Formation in the northern margin of the North China Block (NCB) and Xibiehe Formation (molasse) in the Bainaimiao arc belt (BAB), which could provide strong evidence indicating the affinity of the BAB and the evolution of the southeast Central Asian orogenic belt (CAOB). Zircon U-Pb data of siltstone samples and paleontological data indicate the Ayadeng Formation dates back to the Early Ordovician. Although its location is near the NCB, its zircon age spectra and paleontology share a closer affinity with those of Tarim and NE Gondwana, as the U-Pb data suggest an age range of 490–2 192 Ma (peak age=629, 788, 965 and 1 935 Ma), and similar gastropod fossils are found in Tarim and NE Gondwana. The U-Pb ages of meta-sandstone samples in the Xuniwusu Formation indicate a shared inheritance with the Ayadeng Formation (before 440 Ma), and the U-Pb ages of sandstone samples in the Xibiehe Formation are concentrated, with age peaks centered at ca. 420 Ma. Fossil corals occur in these two formations, and their age components also indicate a collisional setting. Therefore, it is speculated that the BAB drifted away from Tarim or NE Gondwana during the Ordovician and became attached to northern NCB between 440–420 Ma as an exotic terrane. During the Early Paleozoic, there may have occurred a collision between an arc and a continental block. KEY WORDS: detrital zircon, paleontology, Bainaimiao arc belt, North China Block. 0
INTRODUCTION The Central Asian orogenic belt (CAOB), or Altaids, is one of the largest Phanerozoic orogenic systems. It is located between the North China Block (NCB) and Tarim (TA) to the south, and the Siberian Carton (SC) to the north (Wilde, 2015; Windley et al., 2007; Xiao et al., 2003; Jahn et al., 2000; Şengör et al., 1993). This area has been of considerable interest to researchers in recent years, as it was formed via mu
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