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黑龙江霍龙门地区位于兴蒙造山带东部的兴安地块和松嫩地块接触带上,区内花岗岩类以晚古生代花岗岩为主,岩性主要为正长花岗岩、二长花岗岩、碱长花岗岩和二长闪长岩等。研究区的正长花岗岩的SHRIMP锆石U-Pb定年结果为294.8 Ma±1.8Ma,表明其形成于早二叠世,且在早三叠世(244.6 Ma±4.1 Ma)遭受了较弱的岩浆侵位事件的叠加影响。该时代岩石的主量元素具有高钾(K_2O质量分数平均为4.52%)、富钠(Na_2O质量分数平均为3.85%)、略富铝(Al_2O_3质量分数平均为13.73%)、低镁(MgO质量分数平均为0.21%)和贫磷(P_2O_5质量分数平均为0.06%)贫钙(CaO质量分数平均为0.61%)的特征;微量元素表现出Th,Zr,Nd,Rb明显富集,而Ba,Sr,P,Ti明显亏损;稀土元素具有轻稀土元素富集、重稀土元素相对亏损的特征,有较明显的负Eu异常(δEu平均为0.49),轻重稀土元素分馏程度较强。岩石总体上属于高钾钙碱性系列花岗岩。花岗岩的R_1-R_2构造环境判别图解与微量元素Rb-Yb+Nb,Rb-Yb+Ta构造环境判别图解显示,该期发育的早二叠世花岗岩处于碰撞造山晚期向造山期后伸展的构造环境,结合区域北东向大量分布晚石炭世-早二叠世期间反映造山期后伸展环境的A型花岗岩的特征及本区所处的构造环境推测,研究区内早二叠世花岗岩应为兴安地块与松嫩地块北东向碰撞造山晚期向造山期后伸展拉张环境下岩浆侵位的产物。
The Huolongmen area of Heilongjiang is located in the contact zone between the Xing’an block and the Songnen block in the eastern part of the Xingmeng orogenic belt. The granitic rocks in the area are dominated by the Late Paleozoic granites. The lithologies are mainly of the orthoclase, monzogranite, Diorite and so on. The SHRIMP zircon U-Pb dating of the orthoclase granites in the study area was 294.8 Ma ± 1.8Ma, indicating that it was formed in the Early Permian and suffered a weaker magma in the Early Triassic (244.6 Ma ± 4.1 Ma) Overlapping effects of emplacement events. The main elements of this age rock have high potassium (K 2 O 5 average 4.52%), sodium rich (average Na 2 O 3 3.85%), slightly aluminum (Al 2 O 3 average 13.73%), low magnesium (0.21% on average) and lean P (average 0.06% on P 2 O 5). The contents of trace elements such as Th, Zr, Nd and Rb were obviously enriched while those of Ba, Sr, P, and Ti. The rare earth elements have the characteristics of light rare earth elements enrichment and heavy rare earth elements loss, and have obvious negative Eu anomalies (δEu average of 0.49). The fraction of light and heavy rare earth elements is highly fractionated. The rocks are generally high-K calc-alkaline series of granites. The discrimination of R_1-R_2 tectonic setting and the Rb-Yb + Nb, Rb-Yb + Ta tectonic setting of granite show that the Early Permian granites of this period were in the tectonic environment of late collision orogeny to extension after orogeny , Combined with the characteristics of the A-type granites reflecting the extensional environment during the late Carboniferous-Early Permian during the Late Carboniferous with a large distribution in the north east of the area and the tectonic setting in this area, it is suggested that the Early Permian granites in the study area should be Xing’an Late Pleistocene orogeny of Songnen Tennessee Massif to magmatic emplacement in extensional extension after orogeny.