伊犁盆地白垩纪剥露事件的裂变径迹证据  被引量:16

CRETACEOUS DENUDATION OF THE ILI BASIN AS REVEALED BY FISSION-TRACK THERMOCHRONOLOGY

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作  者:宫红良[1] 陈正乐[1] 胡远清 李丽[1] 李胜祥[3] 郑恩玖 韩效忠[3] 

机构地区:[1]中国地质科学院地质力学研究所,北京100081 [2]湖北地矿局鄂东北地质大队,湖北孝感432100 [3]核工业北京地质研究院,北京100029 [4]核工业地质局216大队,乌鲁木齐810001

出  处:《地质力学学报》2007年第1期42-50,共9页Journal of Geomechanics

基  金:国家重点基础研究发展计划"973"项目(2001CB409808;2001CB7110013);国家自然科学基金资助项目(40572116)

摘  要:本文利用砂岩中磷灰石的裂变径迹方法,研究了伊犁盆地中生代抬升-剥露事件。根据磷灰石裂变径迹测年结果,开展了温度-时间热模拟反演研究,结果揭示出伊犁盆地在115-95Ma期间存在一期重要的抬升-剥露冷却事件,剥蚀量至少可达1.8km,剥蚀速率至少为0.09mm/a。区域资料对比分析表明中晚白垩世的抬升剥露事件,在天山地区乃至整个新疆的造山带普遍存在。The fission-track dating method has been widely used to constrain the exhumation of mountains and tectono-thermal evolution of basins. This paper mainly presents the results of apatite fission-track dating and discusses the Mesozoic dating revealed that the fission-track ages of three uplift-denudation event in the Hi basin. Fission-track sandstones from drilling wells at the south margin of the basin are 112.6 ± 9, 79.3 ± 11.4 and 94.0 ± 7.4 Ma respectively, and that the corresponding fissiontrack lengths are 13.45 ± 0.17, 13.15 ± 0.16 and 13.17 ± 0.17μm respectively with a single peak distribution pattern. Further temperature-time modeling of apatite was conducted using the apatite fissiontrack solution program after the model of Ketcham, based on measurements of the fission-track lengths and pooled ages. The results show that one important uplift-denudation and cooling event took place in the Ili basin at 115-95 Ma. This cooling event is fairly consistent with the absence of Upper Jurassic- Lower Cretaceous strata in the basin, suggesting the uplift and subsequent denudation of the Hi basin during this period of time. The coexistence of the single apatite fission-track ages older and younger than the sedimentation age indicates that the apatite fission track was partially annealed after sedimentation as response to the temperature increase resulting from the burial. Supposing that the geothermal gradient is 30℃/km and that the temperatures of the partial annealing zone of apatite fission track vary from 80℃ to 120℃, it can be estimated that the samples were buried at - 2.6-4 km depth and that at least at least 1.8-km-thick material has been denuded with a denudation ratio of 0.09mm/a during the Mid-Late Cretaceous ( 115 - 95Ma). Correlation and analysis of regional data suggest that the Mid-Late Cretaceous uplift and denudation event was widespread in the whole Tianshan Range and even the whole orogenic belt in northern Xinjiang.

关 键 词:伊犁盆地 裂变径迹 剥露 白垩纪 天山造山带 

分 类 号:P542[天文地球—构造地质学] P548[天文地球—地质学]

 

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