CAJ | 학술논문

吉林通化二密铜矿区次火山岩为其成矿的主要围岩。该次火山岩成岩时代未定，对其成岩及成矿机理等问题仍有很大的争论。本文即通过利用LA-MC-ICP-MS锆石U-Pb分析测定了该次火山岩的形成时代：二长闪长玢岩(JEM02)、石英二长闪长岩(JEM03-1)以及石英二长岩(JEM03-2)锆石的206Pb/238U 加权平均年龄分别为(95.71±0.33) Ma (MSWD=1.6)、(97.18±0.46) Ma (MSWD=1.19)和(96.10±0.50) Ma (MSWD=2.0)，与其相应的206Pb/238U-207Pb/235U 谐和年龄一致。松顶山次火山岩侵位的先后顺序为：石英二长闪长岩、石英二长岩、二长闪长玢岩。通过主、微量元素分析，本文认为该次火山岩为碰撞后到晚造山或非造山环境下形成的花岗岩-A 型花岗岩的系列。该次火山岩形成的过程为：在中国东部岩石圈减薄的过程中，地幔物质上涌与地壳发生强烈的相互作用形成富碱的钙碱性岩浆。该岩浆在岩浆房中进一步分异形成二长-闪长岩浆和花岗斑岩岩浆。两种岩浆先后沿火山喷发通道浅成侵入形成次火山岩。
길림통화이밀동광구차화산암위기성광적주요위암。해차화산암성암시대미정，대기성암급성광궤리등문제잉유흔대적쟁론。본문즉통과이용LA-MC-ICP-MS고석U-Pb분석측정료해차화산암적형성시대：이장섬장분암(JEM02)、석영이장섬장암(JEM03-1)이급석영이장암(JEM03-2)고석적206Pb/238U 가권평균년령분별위(95.71±0.33) Ma (MSWD=1.6)、(97.18±0.46) Ma (MSWD=1.19)화(96.10±0.50) Ma (MSWD=2.0)，여기상응적206Pb/238U-207Pb/235U 해화년령일치。송정산차화산암침위적선후순서위：석영이장섬장암、석영이장암、이장섬장분암。통과주、미량원소분석，본문인위해차화산암위팽당후도만조산혹비조산배경하형성적화강암-A 형화강암적계렬。해차화산암형성적과정위：재중국동부암석권감박적과정중，지만물질상용여지각발생강렬적상호작용형성부감적개감성암장。해암장재암장방중진일보분이형성이장-섬장암장화화강반암암장。량충암장선후연화산분발통도천성침입형성차화산암。
The sub-volcanic rocks in the Ermi copper deposit constitute the host rocks of the copper orebodies. As their ages remain unclear, many basic geological problems, such as the mechanism of their intrusion and the mineralization of the deposit, remain controversial. In this paper, the technique of LA-MC-ICP-MS was applied to determining the age of the sub-volcanic rocks. The results show that the weighted206Pb/238U ages of the zircons from monzodiorite porphyrite (JEM02), monzodiorite (JEM03-1) and quartz monzonite (JEM03-2), are (95.71±0.33) Ma (MSWD=1.6), (97.18±0.46) Ma (MSWD=1.19), and (96.10±0.50) Ma (MSWD=2.0), respectively, which are consistent with their corresponding concordant ages, and therefore the intrusion sequence of the sub-volcanics should be quartz monzodiorite, quartz monzonite, and monzodiorite porphyrite. According to the investigation of the composition of the sub-volcanics, the sub-volcanics should be island-arc granitoid-A type granitoid formed in the environment from the post-collision to late-orogenic or anorogenic stage. Combined with the ages of these sub-volcanics, the formation process of the sub-volcanics are considered to be as follows: the lithospheric thinning of eastern China triggered the interaction between the enriched mantle and the crust, and formed the calc-alkaline magma with alkali enrichment. The calc-alkaline magma evolved into two types of magma (monzodiorite-quartz monzonite magma and monzodiorite porphyrite-granite porphyry magma) in the magma chamber in the course of the magma rising, and formed the two kinds of sub-volcanics.