柴达木盆地现今大地热流与晚古生代以来构造-热演化  

Present-day heat flow and tectonic-thermal evolution since the late Paleozoic time of the Qaidam basin

作　　者：李宗星[1] 高俊[2] 郑策[1,3] 刘成林[1] 马寅生[1] 赵为永[4] 

机构地区：[1]中国地质科学院地质力学研究所页岩油气调查评价重点实验室,北京100081 [2]中国地质大学(北京)水资源与环境工程北京市重点实验室,北京100083 [3]中国石油大学(北京),北京102249 [4]中石油青海油田分公司勘探开发研究院,甘肃敦煌736202

出　　处：《地球物理学报》2015年第10期3687-3705,共19页Chinese Journal of Geophysics

基　　金：国家自然科学基金项目(41302202);中国地质科学院地质力学研究所基本科研项目(DZLXJK201305)资助

摘　　要：依据钻孔系统稳态测温、静井温度资料与实测热导率数据分析了柴达木盆地地温场分布特征,建立了柴达木盆地热导率柱,新增了17个大地热流数据.柴达木盆地现今地温梯度介于17.1～38.6℃·km^-1,平均为28.6±4.6℃·km^-1,大地热流介于32.9～70.4mW·m^-2,平均55.1±7.9mW·m^-2.盆地不同构造单元地温场存在差异,昆北逆冲带、一里坪坳陷属于＂高温区＂,祁南逆冲带属于＂中温区＂,三湖坳陷、德令哈坳陷及欧龙布鲁克隆起属于＂低温区＂,盆地现今地温场分布特征受控于地壳深部结构、盆地构造等因素.以现今地温场为基础,采用磷灰石、锆石裂变径迹年龄分布特征定性分析与径迹长度分布数据定量模拟相结合,研究了柴达木盆地晚古生代以来的沉积埋藏、抬升剥蚀和热演化史,并结合区域构造背景,对柴达木盆地构造演化过程进行了探讨,研究表明柴达木盆地晚古生代以来经历了六期（254.0—199 Ma,177—148.6 Ma,87—62 Ma,41.1—33.6 Ma,9.6—7.1 Ma,2.9—1.8 Ma）构造运动,六期构造事件与研究区构造演化的动力学背景相吻合.其中白垩纪末期（87—62 Ma）的构造事件导致了柴达木盆地东部隆升并遭受剥蚀,欧龙布鲁克隆起形成雏形,柴达木盆地北缘在弱挤压环境下形成坳陷盆地;中新世末的两期构造事件（9.6—7.1 Ma和2.9—1.8 Ma）使柴达木盆地遭受强烈挤压,盆地快速隆升,构造变形强烈,基本形成现今的构造面貌.The Qaidam basin is the largest intermountain basin on the northern margin of the Tibetan plateau,and is one of three major petroliferous basins in western China.The characteristics of tectonic-thermal evolution of this basin are important for understanding the uplift mechanism ofthe Tibetan plateau.This work studies the terrestrial heat flow and thermal history of the basin,which would help research the regional dynamics and tectonic evolution of the basin and can be applied to the petroleum resource assessment in this region.This work employed the advanced temperature continuous acquisition system which measures the deep well steady state temperature at a large scale and high accuracy.Then mass of rock thermal conductivity was tested by the optical scanning method. Borehole temperature measurement data were fitted linearly using the least squares method,yielding 17 borehole profiles of geothermal gradients.Furthermore,original temperature measurement data from previous studies were re-analyzed,resulting in 56 geothermal gradients and the measured heat flow data of boreholes.Based on the present geothermal field,the time-temperature history of the samples was simulated by the combination of analysis of apatite fission track ages with modeling of fission track length distribution.For this simulation,the one-component annealing model,Monte Carlo method,and the software Hefty were used.Apatite samples enclosed track length values and the median age were adopted to simulate the basic parameters,with kinetic parameter（Dpar）as the initial value of 1.65,and the initial track length 16.3μm.To the zircon fission track samples which did not pass χ^2 test（P（χ^2〈）5%）,decomposition on single grain fission track age data and frequency statistics analysis were carried out.Based on the analysis of thermochronological dating,we have studied the burial history,uplift and denudation and thermal history of the Qaidam basin.Then we analyzed the tectonic evolution of the Qaidam basin combining with regional tectonic

关 键 词：地温梯度 大地热流 裂变径迹 构造-热演化 柴达木盆地 

分 类 号：P314[天文地球—固体地球物理学]