摘要
根据三江盆地绥滨断陷滨参1井基底花岗岩锆石LA-ICP-MS U-Pb定年结果,探讨了盆地基底的性质。滨参1井基底花岗岩中的锆石呈自形—半自形晶,并具有典型的岩浆生长环带;锆石的Th/U值为0.22～0.82,表明其岩浆成因。花岗岩中锆石22个测点的206Pb/238U年龄值为427～502Ma,其加权平均年龄分为2组,分别为(430±8)Ma和(496±6)Ma。(430±8)Ma的年龄代表了三江盆地绥滨断陷基底花岗岩的形成时代为早志留世晚期;而(496±6)Ma可能是花岗岩浆形成或侵位过程中的捕获锆石年龄,并且它与佳木斯地块麻山群和泛非期片麻状花岗岩的形成时间一致。上述结果表明:三江盆地绥滨断陷基底中存在加里东期花岗岩,三江盆地西部基底与佳木斯地块的属性相同。
Based on the LA-ICP-MS zircon dating of the basement granite from the well Bincan 1, the characters of the basement in the Sanjiang basin are discussed. Zircons from the granite of the well Bincan 1 are euhedral to subhedral in shape and show the typical oscillatory zoning, which indicates their magmatic origin. Their Th/U ratios ranging from 0.22 to 0.82 imply that they derived from crystallization of magma.206Pb/238U ages of zircons from the granite are between 427 Ma and 502 Ma, weighted mean 206Pb/238U ages are subdivided into two groups, i.e., （430±8） Ma and （496±6） Ma, respectively. The age of （430±8） Ma represents the formation time of the basement granite beneath the Suibin depression, i.e., the Early Silurian, whereas the age of （496±6） Ma represents the timing of captured zircons during the formation of granitic magma and/or magmatic emplacement. These captured zircons are temporally consistent with the Mashan Group and the Pan-African gneissic granites within the Jiamusi massif. It’s concluded that the there occur Calidonian granites within the basin basement. Moreover, the basement beneath the Suibin depression within the Sanjiang basin has the same geological features as the Jiamusi massif.
出处
《吉林大学学报（地球科学版）》
EI
CAS
CSCD
北大核心
2010年第4期955-960,共6页
Journal of Jilin University：Earth Science Edition
基金
国家油气选区专项(XQ2004-07-04)
