| 江汉盆地始新统滩坝砂沉积的物源分析及其对古气候的响应——来自碎屑锆石的证据 |
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| 引用本文：周婧,何云龙,彭伟,张亮,黄华,杜学斌,张成,杨允柳.2025.江汉盆地始新统滩坝砂沉积的物源分析及其对古气候的响应——来自碎屑锆石的证据[J].地球学报,46(6):1173-1187. |
| DOI：10.3975/cagsb.2024.123021 |
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| 基金项目:国家自然科学基金项目(编号: 41502102; 42130408; 42072137) |
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| 中文摘要:近年来的非常规油气勘探表明, 江汉盆地始新统是页岩油富集的重要层系。其中, 江陵凹陷新沟咀组厚层泥岩中发育的滩坝砂为江陵凹陷有利勘探目标之一, 但由于盆地周边复杂的物源体系, 目前仍不清楚滩坝砂沉积物来源。本文对江陵凹陷新沟咀组发育滩坝砂的钻井Hu5与Y1井进行样品采集, 开展碎屑锆石U-Pb年龄测定, 并与周缘潜在物源区的锆石U-Pb年龄进行对比。结果表明, 本文样品与前人碎屑锆石年龄谱皆具有145 Ma左右和440 Ma左右两个年龄主峰。与潜在物源对比和Inverse Monte Carlo混合模型计算后发现, 以湘江147 Ma和432 Ma主峰为主的南部物源是江陵凹陷最主要的物源体系: 其中湘江物源贡献占比65.12%; 华容隆起物源占比24.78%; 沅江物源占比3.79%, 北部汉江物源对盆地贡献较小, 约为6.31%。结合始新世时期中国东部古气候变化和江陵凹陷沉积体系发育背景, 研究认为江陵凹陷滩坝砂主要源于南部湘江三角洲砂体, 并在东亚季风影响形成的环湖沿岸流的作用下, 被搬运至江陵凹陷形成广泛分布的滩坝砂。 |
| 中文关键词:滩坝砂 物源分析 古气候响应 锆石U-Pb定年 江汉盆地 |
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| Provenance Analysis of Beach Bar Deposits During the Eocene Period in Jianghan Basin and Their Response to Paleoclimate: Evidence from Detrital Zircon U-Pb Ages |
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| Abstract:Exploration of unconventional oil and gas in recent years has shown that the Eocene is an important period for shale oil enrichment in the Jianghan Basin, and beach-bar sandstone developed in the thick mudstone of the Xingouzui Formation in Jiangling Sag is a favorable exploration target. However, the provenance of the beach-bar sandstone is still unclear owing to the complex provenance system around the basin. In this study, samples were collected from wells Hu5 and Y1 in the Xingouzui Formation of the Jiangling Sag, a detrital zircon U-Pb age test was conducted, and the results were compared with the zircon U-Pb age of the surrounding potential source area. The results showed that the age spectra of these samples and previous detrital zircons have two main peaks at approximately 145 and 440 Ma. By comparing the potential provenance and Inverse Monte Carlo mixture model calculation, this study found that the southern provenance dominated by the main peaks of 147 and 432 Ma of the Xiangjiang River is the most important provenance in the Jiangling Sag, the contribution of the Xiangjiang River provenance accounts for 65.12%, Huarong uplift accounts for 24.78%, the Yuanjiang River accounts for 3.79%, and the contribution of the northern Hanjiang River source to the basin is approximately 6.31%. Combined with the paleoclimatic changes in eastern China during the Eocene period and the development background of the depositional system in the Jiangling Sag, it is most likely that the beach bar sand in the Jiangling Sag was mainly derived from the Xiangjiang Delta in the south. Under the influence of the East Asian monsoon and related coastal currents, part of the sand in the Xiangjiang Delta was transported to the Jiangling Sag and deposited as widely distributed beach bar sand. |
| keywords:beach bar sandstone provenance analysis response of paleoclimate zircon U-Pb dating Jianghan Basin |
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