小兴安岭逊克地区第四纪高镁安山岩的岩石学、K-Ar年代学及火山地质特征

发布时间：2018-02-26 19:07

本文关键词： 小兴安岭逊克高镁安山岩 K-Ar年龄　出处：《岩石学报》2017年01期 　论文类型：期刊论文

【摘要】：黑龙江省小兴安岭北段逊克地区出露大面积的第四纪火山岩,分布面积约3000km~2。岩性主要为玄武安山岩和玄武质粗面安山岩,还有少量的粗面安山岩和安山岩。逊克火山岩的Si O2含量为54.3%~57.4%,MgO含量变化为3.82%~5.80%,镁指数(Mg#=100×Mg/(Mg+Fe~(2+))变化于49.6~57.8之间,属于高镁安山岩。逊克高镁安山岩火山口的位置分布在火山岩区的南面,根据火山岩区南高北低的地势,推测北边的火山岩是由南侧的岩浆向北流动形成的。岩浆流动形成了具有特征性的火山地貌,如沿河谷形成数公里长的石垄以及大面积的翻花熔岩形成的石海景观。火山岩的K-Ar测年结果表明,逊克高镁安山岩可以划分为早更新世(1.12~1.00Ma)和中更新世(0.68~0.25Ma)两期。在第四纪熔岩和河湖相沉积之间还夹有薄层火山灰,推测在岩浆溢流形成大面积熔岩之前有小规模岩浆爆发活动。
[Abstract]:A large area of Quaternary volcanic rocks were exposed in Xunke area of Xiaoxinganling region, Heilongjiang Province, with an area of about 3000km2. The lithology is mainly composed of Black Tortoise andesite and Black Tortoise coarse-faced andesite. There is also a small amount of coarse andesite and andesite. The content of Sio 2 in the xunke volcanic rocks varies from 54.3 to 57.4and the content of MgO varies from 3.82 to 5.80. The mg index of mg #100 脳 Mg/(Mg Fe~(2 changes from 49.6 to 57.8. Belonging to high mafic andesite. The volcanic crater of the xunke high mafic andesite is located on the south side of the volcanic rock area, according to the south high north low terrain of the volcanic rock area, It is assumed that the volcanic rocks in the north are formed by the flow of magma from the south to the north. The flow of magma forms a characteristic volcanic geomorphology. The K-Ar dating results of volcanic rocks show that the rock ridges are several kilometers long along the river valley and the rock landscape is formed by a large area of igneous lava. The Xunke high-mafic andesite can be divided into two periods: early Pleistocene Y1.121.00 Maand Middle Pleistocene 0.680.25Ma. there is also a thin layer of volcanic ash between the Quaternary lava and lacustrine deposits, which suggests that there was a small-scale magmatic eruption before the magmatic overflow formed a large area of lava.
【作者单位】：南京大学地球科学与工程学院内生金属矿床成矿机制研究国家重点实验室;
【基金】：国家自然科学基金项目(41672049) 地震动力学国家重点实验室开放基金课题(LED2016B01) 内生金属矿床成矿机制研究国家重点实验室自主课题(ZZKT-201307)联合资助
【分类号】：P588.144

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