塔里木盆地库车河地质剖面ESR研究  

ESR study of Kuqa river geological profile, Tarim basin.

作　　者：业渝光[1,2] 邬象隆 刁少波[1,2] 蒋炳南 郑显华[1,2] 董砚如 

机构地区：[1]国土资源部海洋沉积开放研究实验室 [2]中国新星石油公司西北石油地质局

出　　处：《石油勘探与开发》1999年第1期25-27,共3页Petroleum Exploration and Development

基　　金：地质行业科技发展基金

摘　　要：库车地区是塔里木盆地中、新生界出露最全的地区，库车河地质剖面最有代表性。在该剖面系统采样２５块（２块花岗岩，２块烧变岩，２１块砂岩），使用电子自旋共振（ＥＳＲ）谱仪，采用热活化技术测定样品的石英氧空位相对浓度，以寻求沉积物中石英氧空位的ＥＳＲ信号与其所接受的剂量（可换算为沉积年龄）之间的关系。首先测定２块花岗岩（上二叠统侵入岩）样品的ＫＡｒ年龄和石英氧空位ＥＳＲ信号强度；再根据第二块花岗岩样品的ＫＡｒ年龄（２２７．６±３．３４Ｍａ）和ＥＳＲ信号强度，计算出２块烧变岩的形成年龄（上三叠统烧变岩为３．２６±０．３Ｍａ，中侏罗统烧变岩为２．３３±０．２Ｍａ）。由于侵入岩的热作用和第三纪末的煤层自燃，上二叠统至中侏罗统克孜勒努尔组的１０块砂岩样品没有保持初始ＥＳＲ信号，不能用于研究。上侏罗统齐古组至上第三系康村组（时间间隔约１３０Ｍａ）的１１块砂岩样品石英氧空位ＥＳＲ信号强度与所接受的累积剂量明显线性相关（回归关系式的相关系数为０．９７）。根据这１１块样品的ＥＳＲ年龄估算结果，建议把中侏罗世与晚侏罗世的界线定为１５４～１５８Ｍａ，白垩纪和侏罗纪的界线定为１２５Ｍａ，早白垩世与晚白垩世的界线定为１０５～１０８Ｍａ?Mesozoic and Cenozoic formations outcrop most completely in the Kuqa region in Tarim basin, and Kuqa river profile is the most representative one. 25 samples (2 from granites, 2 from thermometamorphic rocks, and 21 from sandstones) are selected to measure relative concentration of quartz oxygen in the samples by means of an ESR meter using the thermoactivated technique to find out the relationship between the ESR signal of the oxygen vacancy in quartz of the sediments and the dosage accepted (which can be transferred to the age of sedimentation). The K Ar age and the strength of ESR signal of oxygen vacancies in the quartz of the 2 granite samples (Upper Permian intrusive) are measured firstly. According to the K Ar age (227.6±3.34Ma) and the strength of ESR signal of the second granite sample, the formation age of the 2 burned metamorphic rocks are calculated (age of Upper Triassic burned metamorphic rock: 3.26±0.3Ma and Middle Jurassic burned metamorphic rock: 2.33±0.2Ma). Due to the thermal action of the intrusive rocks and spontaneous combustion of coal seams at the end of Tertiary, the initial signals in 10 sandstone samples (Upper Permian Middle Permian Kizilnuer Group) could not be kept , and therefore cannot be used in the study. The strength of ESR signals of the oxygen vacancies in quartz and the accumulated dosage in 11 sandstone samples from Qigu Group, Upper Jurassic to Kangcun Group, Upper Tertiary, (a period of about 130Ma) have a clear linear relationship (with a correlation coefficient of 0.97). With the results of age estimation it is suggested the boundary between Middle Jurassic and Late Jurassic is placed at 154 158Ma; the boundary between Cretaceous and Jurassic age is placed at 125Ma; and that between Early Cretaceous and Late Cretaceous at 105 108Ma. The error of ESR age estimation is about 10%. Oxygen vacancy may be a new geochronometer, and will have a bright future in the estimation of the “barren formation” in the sediments. Subject

关 键 词：沉积物 地质剖面 ESR 地质年代 塔里木盆地 

分 类 号：P512.2[天文地球—地质学] P53