| 大兴安岭南部扎赉特旗团发村晚古生代沉积岩源区和时代限定 |
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| 关键词:southern Da Hinggan Mountains source analysis detrital zircon U-Pb geochronology LA-ICP-MS Middle Triassic Central Asian orogenic belt |
| 基金项目:中国地质调查局地质调查项目(编号: DD20189613; DD2019005);国家自然科学基金项目(编号: 41772233; 41772114) |
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| Constraints of the Provenance and Deposition Time of the Late Paleozoic Sedimentary Rocks in Tuanfa Village, Jalaid Banner, Southern Da Hinggan Mountains |
| A group of Late Paleozoic strata, composed of sandstone, siltstone and mudstone, is distributed in the Jalaid Banner area in southern Da Hinggan Mountains. Due to lack of paleontological fossils and chronological evidence, the previous researchers assigned it to Late Permian Linxi Formation based on stratigraphic correlation. In this study, LA-ICP-MS was used to determine the zircon U-Pb isotopes in sandstone. The detrital zircon dating results of three sandstone samples (18TF-01, 18YSL-04 and 18XBL-01) show that the ages of 219 zircon samples are mainly distributed in six ranges, i.e., 243~269 Ma, 273~298 Ma, 305~339 Ma, 350~377 Ma, 445~507 Ma and 754~1053 Ma. The weighted mean age of the youngest group zircons is 245 Ma. Combined with the age of intrusive granite, the authors hold that the maximum sedimentary age of the formation is Middle Triassic. The ages reflect the multi-source supply characteristics of the strata: 243~269 Ma detrital zircon mainly came from the volcanic activity related to the closure and collisional orogeny of the southwestern part of the Asian-Asian Ocean; 273~298 Ma detrital zircon came from the Dashizhai Formation volcanic rocks; 305~339 Ma zircon is consistent with the volcanic rocks of the Gegenyubao Formation volcanic rocks in formation time; the 350~ 377 Ma detrital zircon has the same age as the volcanic rocks in northern Damingshan Formation; the 754~ 1053 Ma detrital zircon was derived from the Proterozoic magmatism in the Mohe complex, the Xinghuadukou Group and the Jiamusi micro-blocks; the older ~1800 Ma zircon age is consistent with the age of the paleo-continental basement in the Paleo-Asian Ocean. In the sandstone samples, the crystallization age of zircon is similar to that of stratigraphic sedimentary age, implying a background of convergence. Combined with sandstone material composition, zircon age characteristics and the positional relationship between the arc and the basin, the authors hold that the strata were formed in a pre-arc basin under the convergence background during the Middle Triassic. |
| WANG Ming-qian,WANG Tao,JIA Jian-liang,WANG Zong-qi,BAI Yu-ling,CAI Peng-rui,WU Yan-jia.2020.Constraints of the Provenance and Deposition Time of the Late Paleozoic Sedimentary Rocks in Tuanfa Village, Jalaid Banner, Southern Da Hinggan Mountains[J].Acta Geoscientica Sinica,41(1):49-64. |
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