Geochronology and geochemistry of Permo-Triassic sandstones in eastern Jilin Province (NE China): implications for final closure of the Paleo-Asian Ocean
Geochronology and geochemistry of Permo-Triassic sandstones in eastern Jilin Province (NE China): implications for final closure of the Paleo-Asian Ocean
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吉林省东部（中国东北）二叠纪-三叠纪砂岩的年代学和地球化学：对古亚洲洋最终闭合的影响
DOI：
10.1016/j.gsf.2018.03.014
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发表时间：
2019
影响因子：
8.9
通讯作者：
Zhong Wenjian
中科院分区：
文献类型：
--
作者：
Du Qing Xiang;Han Zuozhen;Shen Xiao Li;Han Chao;Song Zhigang;Gao Lihua;Han Mei;Zhong Wenjian
在中国东北部中亚造山带东部，零星的磨拉石沉积标志着造山带的结束，对了解古亚洲洋的演化具有重要意义。然而，构造事件的时间和这些地层之间的关系仍然存在争议。为了更好地约束这些地质事件，对吉林省东部开山屯组（KST）和克岛群（KD）砂岩进行了碎屑锆石U-Pb年代学和地球化学的综合研究。KST组传统上被认为是磨拉石存款。低CIA、PIA、高ICV值和低Th/U、Rb/Sr比值表明，该砂岩来自未成熟的中长英质火成岩源，经历了简单的沉积循环史，化学风化作用相对较弱。KST组两个样品的LA-ICP-MS锆石U-Pb定年结果为748-252 Ma，表明KST组沉积于晚二叠世254.5 ~ 252 Ma之间。锆石主要来源于华北陆块北方。KD群5个样品的碎屑锆石U-Pb年龄为2611-230 Ma，表明KD群样品沉积于早中三叠世（约1000 ~ 2000 Ma）。248-233 Ma）。KD样品的碎屑锆石年龄在2.5Ga、1.8Ga、800-1000 Ma、500 Ma和440-360 Ma处有峰值，表明样品来自佳木斯-兴卡地块和华北克拉通的双向物源。结合前人的研究结果，认为吉林省中东部至少发生了早二叠世（270-262 Ma）、早三叠世（254-248 Ma）和中晚三叠世（242-227 Ma）三次造山事件。PAO的最终闭合发生在沿着长春-延吉缝合带的中晚三叠世242-227 Ma。碎屑锆石年代学数据清楚地记录了CAOB东部PAO的板块会聚和剪刀状闭合。
In the eastern part of the Central Asian Orogenic Belt (CAOB) in northeastern (NE) China, scattered outcrops of molasse deposits mark the ending of an orogeny and are crucial for understanding the evolution of the Paleo-Asian Ocean (PAO). However, the timing of tectonic events and the relationships among these strata remain controversial. To better constrain these geologic events, a comprehensive study of the detrital zircon U-Pb geochronology and geochemistry of the sandstones of the Kaishantun (KST) Formation and Kedao (KD) Group in eastern Jilin Province, NE China, was conducted. The KST Formation is traditionally considered a molasse deposit. The sandstones display low CIA, PIA and high ICV values and low Th/U and Rb/Sr ratios, which suggest that the rocks were derived from an immature intermediate-felsic igneous source and experienced a simple sedimentary recycling history with relatively weak chemical weathering. LA-ICP-MS U-Pb dating of detrital zircons from two samples of the KST Formation yields ages of 748–252 Ma, suggesting that the KST Formation was deposited between 254.5 Ma and 252 Ma in Late Permian. The zircons were mainly derived from the continental northern part of the North China Craton (NCC). In contrast, the U-Pb dating of detrital zircons from five samples of the KD Group yields ages of 2611–230 Ma, suggesting that the KD samples were deposited in the Early to Middle Triassic (ca. 248–233 Ma). The detrital zircon ages for the KD samples can be divided into groups with peaks at 2.5 Ga, 1.8 Ga, 800–1000 Ma, 500 Ma and 440–360 Ma, which suggest that the samples were derived from bidirectional provenances in the Jiamusi-Khanka Block and the NCC. These new data, combined with previously published results, suggest that at least three orogenic events occurred in central-eastern Jilin Province during the Early Permian (270–262 Ma), Early Triassic (254–248 Ma) and Middle–Late Triassic (242–227 Ma). The final closure of the PAO occurred during 242–227 Ma in the Middle–Late Triassic along the Changchun-Yanji suture zone. The detrital zircon geochronological data clearly record plate convergence and the scissor-like closure of the PAO in the eastern CAOB.