张广才岭晚古生代A型花岗岩的年代学及构造环境分析

发布时间：2018-07-04 19:28

本文选题：张广才岭 + 晚古生代　；参考：《吉林大学》2015年硕士论文

【摘要】：张广才岭位于黑龙江省中部。东部以牡丹江断裂为界与佳木斯地块相邻；西部以逊克-铁力断裂为界与松辽盆地相邻；南部延伸到吉林省舒兰市附近；北部穿过黑龙江一直延伸到俄罗斯境内。它是早古生代小兴安岭－松嫩地块与佳木斯地块之间的碰撞造山带，在晚古生代成为海西活动大陆边缘的一部分。张广才岭地区显生宙花岗岩广泛出露，被称之为“巨型花岗岩省”。该区花岗岩在20世纪70年代及以前的区域地质调查中，，由于多数岩体侵入晚古生代地层并与侏罗纪地层呈沉积接触关系，所以前人将该区花岗岩中的绝大部分确定为海西期花岗岩。但随着同位素测年技术的发展，人们通过Rb-Sr、K-Ar等测年方法发现,原本被定为海西期的花岗岩年龄均在印支期（250~222Ma）范围内，因此人们将原来的海西期花岗岩确定为印支期。近年来，随着LA-ICP-MS和SHRIMP等测年技术的发展，人们在确定该地区大部分花岗岩的形成年代为印支期的同时，也发现了早古生代花岗岩和海西期花岗岩的存在。根据前人研究成果，该地区海西期花岗岩大部分属于I型花岗岩，而本文在依托“锡霍特成矿带内生矿产成矿模式和成矿系列境内外对比研究”课题对该地区进行研究的过程中，却发现了海西期A型花岗岩的存在。这些花岗岩体的岩性主要为黑云母二长花岗岩和正长花岗岩。它们的SiO2含量为66.03%~77.20%，K2O+Na2O的含量为7.75%~9.94%，属于碱性系列；A/CNK值为0.91~1.15，A/NK值为0.98~1.51，为准铝质到弱过铝质岩石；稀土元素均显示出了明显的的负铕异常，微量元素表现出Ba、Sr、P、Ti等元素的明显亏损。本文中这些准铝质到弱过铝质的碱性A型花岗岩年龄主要集中在260Ma和300Ma，属于晚古生代的晚石炭世末期到二叠纪晚期。本文通过Maniar、Pearce和Barbarin三种花岗岩构造环境判别方法，并结合该地区的大地构造背景，得出这些A型花岗岩的形成应该与古亚洲洋向佳木斯地块俯冲过程中产生的弧后裂陷有关。
[Abstract]:Zhang Guangcailing is located in the middle of Heilongjiang Province. In the east, the Mudanjiang fault is the boundary of Jiamusi block; in the west, the Xunke-Taili fault is adjacent to the Songliao basin; in the south, it extends near Shulan City, Jilin Province; and in the north, it extends through Heilongjiang to Russia. It is a collisional orogenic belt between the Xiaoxinganling-Songnen block and the Jiamusi block in the early Paleozoic and became a part of the Hercynian active continental margin in the late Paleozoic. Zhang Guang Ciling area Phanerozoic granite widely exposed, known as "giant granite province." In the regional geological survey of the granite in the 1970s and before, most of the granites intruded into the late Paleozoic strata and were in contact with the Jurassic strata. Therefore, most of the granites in this area are determined to be Hercynian granites. However, with the development of isotopic dating techniques, it is found by Rb-SrnK-Ar dating method that the original Hercynian granite ages are within the range of the Indosinian period (250 ~ 222Ma), so the original Hercynian granites are defined as the Indosinian epoch. In recent years, with the development of LA-ICP-MS and shrimp dating techniques, the early Paleozoic and Hercynian granitic granites were found in this area, while the formation age of most granites in the area was determined to be the Indosinian epoch. According to previous studies, most of the Hercynian granites in this area belong to I-type granites. In the course of studying this area based on the subject of "metallogenic model of endogenetic minerals and comparative study of metallogenic series at home and abroad" in the Siholt metallogenic belt, the existence of A-type granites in Hercynian period was found in this paper. The lithology of these granite bodies is mainly biotite monzogranite and syenite granite. Their Sio _ 2 content is 66.03 and the content of K _ 2O and Na _ 2O is 7.75 and 9.94, which belongs to the alkaline series A / C _ (K) = 0.91 ~ 1.15% A / N = 0.98 ~ 1.51, quasi aluminous to weakly peraluminous rocks, and the rare earth elements show obvious negative europium anomaly, and the trace elements show obvious depletion of Bao-Sr-PnTi and so on. In this paper, the ages of these quasi-aluminous to weakly peraluminous alkaline A-type granites are mainly concentrated at 260 Ma and 300 Ma, belonging to late Paleozoic late Carboniferous to late Permian. In this paper, by means of three tectonic environments of Maniarine Pearce and Barbarin, and combining with the tectonic setting of this area, it is concluded that the formation of these A-type granites is related to the back-arc rift produced during the subduction of the paleo-Asian oceanic Jiamusi block.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P588.121;P597.3

【参考文献】