黑龙江省东部饶河杂岩的就位时代与东北东部中生代构造演化  

Emplacement age of the Raohe Complex in eastern Heilongjiang Province and the tectonic evolution of the eastern part of Northeastern China.

作　　者：程瑞玉[1] 吴福元[2] 葛文春[1] 孙德有[1] 柳小明[3] 杨进辉[2] 

机构地区：[1]吉林大学地球科学学院,长春130061 [2]中国科学院地质与地球物理研究所岩石圈演化国家重点实验室,北京100029 [3]西北大学地质学系大陆动力学国家重点实验室,西安710069

出　　处：《岩石学报》2006年第2期353-376,共24页Acta Petrologica Sinica

基　　金：国家自然科学基金资助项目(40325006);全国油气资源战略选区调查与评价项目(XQ-2004-07)。

摘　　要：黑龙江省东部饶河杂岩由含放射虫深海沉积岩以及镁铁质的熔岩和侵入岩组成,并被视为大洋壳的残片。该杂岩被晚期蛤蚂河和太平村花岗岩侵入。锆石U-Pb年龄结果表明,上述两花岗岩岩体均形成于早白垩世,其中蛤蚂河岩体形成于131、124和～115Ma三个阶段,太平村岩体形成于111～114Ma左右。饶河杂岩中辉长岩的锆石U-Pb年龄为166±1Ma,深海沉积岩中最晚出现的放射虫的时代为160～150Ma,显示饶河杂岩的就位应发生在150～131Ma的晚侏罗世—早白垩世,古地磁资料显示本区自晚三叠世—侏罗纪有明显的从低纬度向高纬度的北移现象：从而表明在晚侏罗世—早白垩世及以前该区存在太平洋板块的俯冲-走滑作用。岩石学研究显示,两花岗岩岩体中均存在岩浆结晶成因的堇青石,并具有过铝质花岗岩的特点,为典型的来源于沉积岩部分熔融形成的S型花岗岩。Hf同位素测定发现,这些花岗岩中的锆石具有较高的^(176) Hf/^(177)Hf同位素比值和较正的ε_(Hf)(t)值,以长英质地壳为源岩的Hf同位素模式年龄为500～780Ma,说明其源岩应为新元古代—显生宙新增生的地壳物质,从而反映在晚侏罗世—早白垩世以前本区曾发生过显著的地壳抬升与风化剥蚀。Raohe Complex, located in the eastern Heilongiiang Province and composed of deep oceanic sediments and mafic igneous rocks ,was considered as slice of oceanic crust and intruded by Hamahe and Taipingcun granites. Zircon U-Pb dating indicated that both of plutons were emplaced in Early Cretaceous, with the Hamahe pluton formed at three individual stages （ 131Ma, 124Ma and ≈ 115Ma, respectively） and the Taipingcun pluton at 111 - 114Ma. However, the gabbro in Raohe Complex was formed at 166±1Ma, and the latest radiolarian in the deep oceanic sediments is about 160 - 150Ma. Therefore, it is concluded that the emplacement of the Raohe Complex took place at 150 - 131Ma of Late Jurassic-Early Cretaceous, indicating that there existed the Pacific plate subduction and striking-slip in this area before and during Late Jurassic-Early Cretaceous. Petrological studies indicate that both plutons contained magmatic cordierites and show peraluminous characteristics, suggesting their S-type affinity derived from partial melting of the sedimentary rocks. Hf isotopic analyses show that the zircons from plutons have high ^176 Hf/^177 Hf ratios and positive εHf（t） values, and the Hf isotope model age with the felsic crust rocks is 500 - 780Ma, which indicates that their protolith should be the juvenile crust formed in Neo Proterozoic-Phanerozoic. Therefore, it is suggested that there existed significant crust uplift and weathering before Late Jurassic-Early Cretaceous in the area.

关 键 词：饶河地区 S型花岗岩 锆石U—Pb定年 LU-HF同位素 

分 类 号：P588.121[天文地球—岩石学] P597.3[天文地球—地质学]