东北三江盆地始新世花岗闪长岩的发现及其地质意义:锆石U-Pb年代学、地球化学和Sr-Nd-Hf同位素证据
发布时间：2018-08-29 08:13
【摘要】：本文报道了三江盆地富锦地区临山花岗质岩体的锆石LA-ICP-MS U-Pb年龄、全岩地球化学和Sr-Nd同位素与锆石Hf同位素资料,以确定其形成时代、岩石成因、源区性质及其构造属性。花岗闪长岩中的锆石均呈半自形-自形晶,震荡环带发育,Th/U比值=0.31~1.92,指示其岩浆成因。对岩浆锆石的定年结果显示,临山花岗闪长岩形成于~54Ma,这是目前东北地区报道的最年轻的花岗质岩浆作用。该期花岗闪长岩的SiO_2含量主要在68.71%~72.42%之间,Na_2O=3.29%~4.41%,K_2O=2.79%~3.47%,Na_2O/K_2O=0.95~1.58,A/CNK=0.99~1.12;该区花岗闪长岩富集轻稀土元素(LREEs)和大离子亲石元素(LILEs),亏损重稀土元素(HREEs)和高场强元素(HFSEs),且轻重稀土元素分馏较强[(La/Yb)N=21.8~34.1]。样品无明显Eu异常(δEu=0.84~1.19)。它们的(87Sr/86Sr)i=0.7068~0.7071,εNd(t)介于-2.4~-2.3之间;锆石εHf(t)值介于+1.7~+5.7之间,二阶段Hf模式年龄(tDM2)介于765~1020Ma之间。上述特征表明,该期花岗闪长岩属于弱过铝质高钾钙碱性I型花岗岩,其原始岩浆起源于中元古代末-新元古代期间增生的陆壳物质的部分熔融。对三江盆地与佳木斯地块东缘已发表锆石Hf同位素资料进行总结和时空对比发现,佳木斯地块东缘和三江盆地具有相似的地壳增生历史,暗示三江盆地之下的基底物质可能仍归属于佳木斯地块范畴。另外,新生代临山岩体的识别,限制了富锦隆起的时限为始新世之后,并非前人认为的中生代。
[Abstract]:Zircon LA-ICP-MS U-Pb age, whole rock geochemistry, Sr-Nd isotopic and zircon Hf isotopic data of Linshan granitic body in Fujin area, Sanjiang Basin, are reported in this paper, in order to determine its formation age, petrogenesis, source nature and tectonic attributes. The zircon in granodiorite is semi-automorphic and the Th-U ratio is 0.31 ~ 1.92, indicating the magmatic origin of the magma. The dating results of magmatic zircon show that the Linshan granodiorite was formed in Guan54 Ma. this is the youngest granitic magmatism reported in Northeast China. 璇ユ湡鑺卞矖闂暱宀╃殑SiO_2鍚噺涓昏鍦，
本文编号：2210707
[Abstract]:Zircon LA-ICP-MS U-Pb age, whole rock geochemistry, Sr-Nd isotopic and zircon Hf isotopic data of Linshan granitic body in Fujin area, Sanjiang Basin, are reported in this paper, in order to determine its formation age, petrogenesis, source nature and tectonic attributes. The zircon in granodiorite is semi-automorphic and the Th-U ratio is 0.31 ~ 1.92, indicating the magmatic origin of the magma. The dating results of magmatic zircon show that the Linshan granodiorite was formed in Guan54 Ma. this is the youngest granitic magmatism reported in Northeast China. 璇ユ湡鑺卞矖闂暱宀╃殑SiO_2鍚噺涓昏鍦，
本文编号：2210707
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