摘要
自晚三叠世以来,川西坳陷先后经历了安县运动、印支晚幕运动和喜山运动,造成工区内地层的多次抬升剥蚀,形成了多个不整合面。本次研究是通过镜质体反射率和声波时差法,恢复川西坳陷中段喜山期的剥蚀厚度。通过镜质体反射率恢复的剥蚀厚度为844 m～3 192.6 m,平均为1 642.5 m;通过声波时差法恢复的剥蚀厚度为1 015.5 m～1 676.1 m,平均为1 386.4 m。这一差值是由于工区内普遍存在的超压,对声波时差法恢复剥蚀厚度的影响造成的。剥蚀厚度恢复结果表明:川西坳陷具有从北往南剥蚀厚度减小的特征;从西往东,则表现为先变小后变大的特征。在鸭子河地区剥蚀较强、往东到马井地区剥蚀厚度变小,再往东到中江,剥蚀厚度又变大。
Uplift and erosion of stratigraphy in a basin is a common phenomenon. Denudation Recovery of stratigraphy is the key and basis during the study of basin evolution and resource assessment. Tectonic movements have occurred frequently in the middle section of west Sichuan depression since the late Triassic, including the Indosinian movement, the Anxian movement, the Yanshan movement and the Himalaya movement. They are mainly caused by compressive stresses leading to many unconformity surfaces. Vitrinite reflectance distribution characteristics and the sonic velocity analysis method are used in this study to recover the denuded amount caused by three movements respectively. The erosion thickness is 844 m ～3 192. 6 m which is restored by vitrinite reflectance,and the average thickness is 1642.5 m;the erosion thickness is 1015.5.m～1676.1 m which is restored by waves time law, and the average thickness is 1 386. 4 m. The difference is produced by super pressure that generally exists in study area. The calculation results of the denuded amounts show that the thickness of erosion has decreased fromnorth to south ;The thickness has increased from west to east, in Yazihe region, the erosion is strong, smaller thickness of erosion decreased from east to the Majin regional. Then Zhongjiang erosion has become a large thickness.
出处
《物探化探计算技术》
CAS
CSCD
2011年第2期189-194,108,共6页
Computing Techniques For Geophysical and Geochemical Exploration
基金
国家自然科学基金资助项目(40772804)
关键词
川西坳陷
喜山期
剥蚀厚度
镜质体反射率
声波时差
west Sichuan depression
himalayan
erosion thickness
vitrinite reflectance
sonic time difference
