中上扬子地区印支期以来抬升剥蚀时限的确定

Determination of onset of uplifting for the Mid-upper Yangtze area after Indosinian event

采用磷灰石裂变径迹年龄空间分布特征定性分析与径迹长度分布数据定量模拟相结合,约束了中上扬子地区的抬升剥蚀时限.江汉盆地在157～97Ma和10 Ma以来发生了两期大规模抬升剥蚀;湘鄂西武陵地区、黔中隆起自137Ma开始持续抬升剥蚀;鄂西渝东、川东褶皱带从97 Ma开始持续抬升剥蚀;川东北和川中地区于56 Ma才开始遭受抬升剥蚀;川西滇西地区则自23 Ma以来经历了较大规模的抬升剥蚀.印支期以来,中上扬子不同地区抬升剥蚀开始的时间存在明显差异性,总体上由东往西逐渐变晚.齐岳山断裂带以东,大规模抬升剥蚀始于中燕山期(J_3-K_1);齐岳山断裂与华蓥山断裂带之间的川东高陡背斜带抬升剥蚀始于晚燕山期(K_2);华蓥山断裂与龙泉山断裂之间的川中和缓褶皱带晚期抬升剥蚀始于喜马拉雅早期(E);龙泉山断裂带以西的川西凹陷晚期抬升剥蚀始于喜马拉雅晚期(N).

The onset of uplifting in the Mid-upper Yangtze region is constrained by the combination of analysis of apatite fission track （AFT） ages with modeling of fission track length distribution. Two episodes of uplifting in Jianghan basin occurred within 157-97Ma and 10- 0 Ma; Xiang＇exi-Wuling region and Qianzhong hights experienced an uplifting of 137 -0 Ma; Exiyudong, Chuandong folds and Chuandongnan regions, 9740 Ma; Chuandongbei and Chuanzhong regions, 56-0 Ma; Chuanxi and Dianxi areas 23-0 Ma. The general trend is that the onsets of uplifting for different tectonic units in the Mid-upper Yangtze area decrease westward. The major faults of Qiyueshan, Huanyinshan and Longquanshan controled the boundaries of the onsets of uplifting. The onsets of uplifting for the regions eastern of Qiyueshan fault, in between of Qiyueshan and Huanyinshan faults, in between of Huanyinshan and Longquanshan faults, western of Longquanshan fault are late Jurassic-early Cretaceous （J3-K1）, late Cretaceous （K2）, Paleogene （E） and Neogene （N）, respectively.