【摘要】：本文報道了三江盆地富錦地區(qū)臨山花崗質巖體的鋯石LA-ICP-MS U-Pb年齡、全巖地球化學和Sr-Nd同位素與鋯石Hf同位素資料,以確定其形成時代、巖石成因、源區(qū)性質及其構造屬性。花崗閃長巖中的鋯石均呈半自形-自形晶,震蕩環(huán)帶發(fā)育,Th/U比值=0.31~1.92,指示其巖漿成因。對巖漿鋯石的定年結果顯示,臨山花崗閃長巖形成于~54Ma,這是目前東北地區(qū)報道的最年輕的花崗質巖漿作用。該期花崗閃長巖的SiO_2含量主要在68.71%~72.42%之間,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;該區(qū)花崗閃長巖富集輕稀土元素(LREEs)和大離子親石元素(LILEs),虧損重稀土元素(HREEs)和高場強元素(HFSEs),且輕重稀土元素分餾較強[(La/Yb)N=21.8~34.1]。樣品無明顯Eu異常(δEu=0.84~1.19)。它們的(87Sr/86Sr)i=0.7068~0.7071,εNd(t)介于-2.4~-2.3之間;鋯石εHf(t)值介于+1.7~+5.7之間,二階段Hf模式年齡(tDM2)介于765~1020Ma之間。上述特征表明,該期花崗閃長巖屬于弱過鋁質高鉀鈣堿性I型花崗巖,其原始巖漿起源于中元古代末-新元古代期間增生的陸殼物質的部分熔融。對三江盆地與佳木斯地塊東緣已發(fā)表鋯石Hf同位素資料進行總結和時空對比發(fā)現,佳木斯地塊東緣和三江盆地具有相似的地殼增生歷史,暗示三江盆地之下的基底物質可能仍歸屬于佳木斯地塊范疇。另外,新生代臨山巖體的識別,限制了富錦隆起的時限為始新世之后,并非前人認為的中生代。
[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，

本文編號：2210707