CAJ | 학술논문

报道了佳木斯地块东部锦山花岗杂岩体的锆石LA-ICPMS U-Pb 定年结果、全岩地球化学和锆石 Hf同位素特征,确定了花岗质岩石的形成时代、源区性质及其地球动力学背景,同时也为中亚造山带东段的构造演化提供重要线索.花岗岩的锆石主要呈自形—半自形晶,发育显著的震荡生长环带,w(Th)/w(U)值在0．12~1．20之间,显示其典型的岩浆成因.测年结果表明这些花岗质岩石形成于早—中二叠世(260~278 Ma).地球化学特征显示：花岗质岩石w(SiO2)值为66.75％~70.10％,w(Na2 O)值为4.40％~5.23％,w(K2 O)值为0.77％~2.80％,w(K2 O)/w(Na2 O)值为0.18~0.61,A/CNK 值为0.97~1.14；这些岩石富集大离子亲石元素(Rb、Ba 和K),相对亏损高场强元素(Nb、Ta、P、Zr、Ti 和 Hf).锆石原位 Hf 同位素分析显示,花岗岩的εHf(t)值介于－0．8~7．7之间,两阶段 Hf模式年龄介于953~1578 Ma之间.该区花岗质岩石属于偏铝质—弱过铝质的低钾—中钾钙碱性 I 型花岗岩,原始岩浆起源于中—新元古代增生的下地壳物质的部分熔融.结合区域研究资料,研究区内早—中二叠世花岗岩就位于活动大陆边缘环境,其形成可能与佳木斯地块东侧古大洋板块的西向俯冲作用有关.
보도료가목사지괴동부금산화강잡암체적고석LA-ICPMS U-Pb 정년결과、전암지구화학화고석 Hf동위소특정,학정료화강질암석적형성시대、원구성질급기지구동역학배경,동시야위중아조산대동단적구조연화제공중요선색.화강암적고석주요정자형—반자형정,발육현저적진탕생장배대,w(Th)/w(U)치재0．12~1．20지간,현시기전형적암장성인.측년결과표명저사화강질암석형성우조—중이첩세(260~278 Ma).지구화학특정현시：화강질암석w(SiO2)치위66.75％~70.10％,w(Na2 O)치위4.40％~5.23％,w(K2 O)치위0.77％~2.80％,w(K2 O)/w(Na2 O)치위0.18~0.61,A/CNK 치위0.97~1.14；저사암석부집대리자친석원소(Rb、Ba 화K),상대우손고장강원소(Nb、Ta、P、Zr、Ti 화 Hf).고석원위 Hf 동위소분석현시,화강암적εHf(t)치개우－0．8~7．7지간,량계단 Hf모식년령개우953~1578 Ma지간.해구화강질암석속우편려질—약과려질적저갑—중갑개감성 I 형화강암,원시암장기원우중—신원고대증생적하지각물질적부분용융.결합구역연구자료,연구구내조—중이첩세화강암취위우활동대륙변연배경,기형성가능여가목사지괴동측고대양판괴적서향부충작용유관.
Zircon LA-ICPMS U-Pb dating results,whole rock geochemistry and zircon Hf isotopic characteristics of Jinshan granitic complex in the eastern Jiamusi massif were reported,the formation age, source characteristics and geodynamics setting of these granitic rocks were identified in order to find the tectonic evolution of the eastern segment of Central Asian orogenic belt.Zircons from Jinshan granite rocks are euhedral-subhedral in shape,and display distinctly oscillatory zoning structures,and values of w(Th)/w(U)are 0.12-1.20,indicating a magmatic origin.The dating results show that the granitic rocks form in Early-Middle Permian (260-278 Ma).The geochemical characteristics show that w(SiO2 ),w(Na2 O),w(K2 O),w(K2 O)/w(Na2 O) and A/CNK values of the granitic rocks are 66.75%-70.10%,4.40%-5.23%,0.77%-2.80%, 0.18-0.61 and 0.97-1.14,respectively;these rocks are rich in large ion lithophile elements (Rb, Ba and K)and depleted in high field strength elements (Nb,Ta,P,Zr,Ti and Hf).In-situ Hf isotope analysis reveals thatεHf (t)of the granite rocks are -0.8-7.7,and the two-stage Hf model ages are 953-1 578 Ma.These granitic rocks belong to low-middle potassium calc-alkaline I-type granites with metaluminous-weakly peraluminous.The primary magma originates from the partial melting of Mesoproterozoic-Neoproterozoic accreted lower crust. Combined with the regional geological investigation, the Early-Middle Permian granites in the study area are emplaced in an active continental margin setting, which is likely related to the westward subduction of Paleo-oceanic plate beneath the Jiamusi massif.