松辽盆地北部三叠纪重要火山-岩浆事件——对晚古生代地层时限的约束  

SIGNIFICANT TRIASSIC VOLCANIC-MAGMATIC EVENT IN THE NORTHERN SONGLIAO BASIN:Constraints on the Late Paleozoic Stratigraphic Timing

作　　者：张海华[1] 张健[1] 陈树旺[1] 郑月娟[1] 苏飞[1] 卞雄飞[1] 黄欣[1] 李晓海[1] 张德军[1] 孙雷[1] ZHANG Hai-hua;ZHANG Jian;CHEN Shu-wang;ZHENG Yue-juan;SU Fei;BIAN Xiong-fei;HUANG Xin;LI Xiao-hai;ZHANG De-jun;SUN Lei(Shenyang Center of China Geological Survey,Shenyang 110034,China)

机构地区：[1]中国地质调查局沈阳地质调查中心,辽宁沈阳110034

出　　处：《地质与资源》2021年第3期249-256,283,共9页Geology and Resources

基　　金：中国地质调查局项目“松辽盆地北部及外围石炭-二叠系油气地质调查”(编号DD20190097).

摘　　要：对松辽盆地北部黑富地3井所钻遇的侵入岩进行同位素U-Pb年代学分析,以探讨其形成期次和构造演化特征,并对所侵入的地层进行时代约束.测试分析结果显示,锆石206Pb/238U年龄的加权平均值为245.5±1.9 Ma,表明侵入岩的结晶年龄为早中三叠世,指示松辽盆地北部发育早中三叠世岩浆热事件.同时存在两组捕获的锆石年龄,一组介于269~295 Ma,年龄的加权平均值为289.0±6 Ma;另一组为313~353 Ma,年龄的加权平均值为338.0±3 Ma.捕获的锆石年龄指示松辽盆地北部基底或深部至少还经历了石炭纪和早—中二叠世等火山活动及岩浆侵位等事件.导致岩浆热事件的构造机制应与古亚洲洋的碰撞拼合及碰撞后的伸展体制有关.脉岩的结晶侵位年龄限制了地层的沉积时代上限,即碎屑岩地层是在245.5±1.9 Ma之前固结成岩.综合其他地质依据,证明碎屑岩层系为晚二叠世林西组.The isotopic U-Pb chronology of intrusive rocks in HFD-3 well in northern Songliao Basin is analyzed to study the formation age and tectonic evolution and determine the timing of invaded strata.The results show that the weighted average of zircon206Pb/238U age is 245.5±1.9 Ma,which reflects the crystallization age of intrusive rock is Early-Middle Triassic,indicating the development of Early-Middle Triassic magmatic thermal event in northern Songliao Basin.There are also two groups of zircon ages:269-295 Ma and 313-353 Ma,with the weighted averages of 289.0±6 Ma and 338.0±3 Ma respectively,indicating the basement or deep part of northern Songliao Basin underwent at least once Carboniferous and Early-Middle Permian volcanic activity and magma emplacement event.The tectonic mechanism leading to the magmatic thermal event should be related to the collision and post-collision extension of Paleo-Asian Ocean.The crystallization emplacement age of dike constrains the upper limit of sedimentary age of strata;that means,the clastic formation was consolidated before 245.5±1.9 Ma.Combined with other geological evidence,it is proved that the clastic rocks belong to the Late Permian Linxi Formation.

关 键 词：松辽盆地 闪长玢岩 锆石U-PB年龄 早中三叠世 岩浆事件 

分 类 号：P597[天文地球—地球化学] P534.51[天文地球—地质学]