LA-ICPMS zircon U-Pb dating of the Heilongjiang Complex in the Luobei area: New constraints for the late Palaeozoic-Mesozoic tectonic evolution of Jiamusi Block, NE China
LA-ICPMS zircon U-Pb dating of the Heilongjiang Complex in the Luobei area: New constraints for the late Palaeozoic-Mesozoic tectonic evolution of Jiamusi Block, NE China
复制标题
萝北地区黑龙江杂岩LA-ICPMS锆石U-Pb定年：佳木斯地块晚古生代-中生代构造演化的新约束
DOI：
10.1002/gj.3443
复制
发表时间：
2020
影响因子：
1.8
通讯作者：
Long Li
中科院分区：
文献类型：
--
作者：
Wei Han;Jian‐Bo Zhou;Simon A.Wilde;Long Li
黑龙江杂岩是一套高压变质岩系，分布于中国东北部佳木斯与松辽地块之间的S缝合带。为了了解黑龙江杂岩的地质年代学和构造格架，我们对萝北的样品进行了调查。黑龙江杂岩由二云母片岩、白云母钠长石片岩、石英片岩、斜长片麻岩、花岗片麻岩、蛇纹岩、蓝片岩、绿片岩、角闪岩和大理岩组成。所有样品的LA-ICPMS测年结果表明，原岩年龄范围为435~210 Ma。这些数据与伊兰地区花岗片麻岩样品的492 Ma±16.6 Ma年龄相结合，表明黑龙江杂岩的原岩形成于~490~~210 Ma的较长时间段。此外，两个样品中的五个锆石颗粒含有变质边缘，其年龄为197 Ma±5.2 Ma。结合黑龙江杂岩被中侏罗世地层覆盖的野外证据，这些结果表明黑龙江杂岩是在210~197 Ma之间变质的，而不是以前认为的白垩纪。这一证据，再加上佳木斯地块东缘晚古生代亲弧火山岩和张广才、小兴安岭同碰撞中生代火山岩的产出，表明黑龙江杂岩是晚古生代潘德拉萨俯冲和中生代古太平洋俯冲的结果。
The Heilongjiang Complex is a sequence of high‐pressure (HP) metamorphic rocks that are distributed along the N‐S suture zone between the Jiamusi and Songliao blocks in NE China. In this study, we investigated samples from Luobei in order to understand the geochronological and tectonic framework of the Heilongjiang Complex. The Heilongjiang Complex consists of two‐mica schist, muscovite‐albite schist, quartz schist, plagioclase gneiss, granitic gneiss, serpentinite, blueschist, greenschist, amphibolite, and marble. LA‐ICP‐MS dating of all samples shows a range of protolith ages from 435 to 210 Ma. These data, together with a 492 ± 6 Ma age from a granite gneiss sample in the Yilan area, indicate that the protoliths of the Heilongjiang Complex were formed over a protracted time span from ~490 to ~210 Ma. In addition, five zircon grains in two samples contain metamorphic rims that yield ages of 197 ± 2 Ma. These results, when combined with field evidence that the Heilongjiang Complex is overlain by Middle Jurassic strata, indicate it was metamorphosed between ~210 and 197 Ma and not in the Cretaceous as previously considered. This line of evidence, plus the occurrence of late Palaeozoic arc‐affinity volcanic rocks in the eastern margin of the Jiamusi Block and syn‐collisional Mesozoic volcanic rocks in the Zhangguangcai and Lesser Xing'an ranges, suggests the Heilongjiang Complex was a result of Panthalassa subduction during the late Palaeozoic and Paleo‐Pacific subduction during the Mesozoic.