阿尔泰造山带晚古生代高温麻粒岩变质作用与塔里木地幔柱活动的成因联系
发布时间：2019-06-25 18:39
【摘要】：阿尔泰造山带是中亚造山带(CAOB)的重要组成部分,在其南缘出露有高温泥质和镁铁质麻粒岩,确定其P-T轨迹对于理解阿尔泰造山带南缘在晚古生代的构造演化历史具有重要意义。通过对该区乌恰沟泥质和镁铁质麻粒岩样品精细的岩相学观察,显示泥质麻粒岩峰期前矿物组合(M0)为黑云母+堇青石±尖晶石+斜长石+石英+钛铁矿,峰期矿物组合(M1)为石榴石+堇青石+黑云母+斜长石+石英+磁铁矿+钛铁矿±斜方辉石±尖晶石±钾长石,退变质矿物组合(M2)为黑云母+斜长石+石英±堇青石等;镁铁质麻粒岩峰期前矿物(M0)主要为黑云母和斜长石等矿物,峰期矿物组合(M1)为斜方辉石+单斜辉石+角闪石+黑云母+斜长石+钾长石+石英+钛铁矿+磁铁矿,退变质过程中形成少量角闪石和斜长石等矿物(M2)。使用传统温压计和平均温压计算方法对其变质峰期及峰期后的P-T条件进行了计算,并利用Thermocalc软件对其中两个泥质麻粒岩样品进行了视剖面图模拟,确定了其峰期变质条件为770-865℃和3.0-5.1 kbar,并得到了两条峰期后近等压冷却(IBC)的P-T演化轨迹,这样的P-T轨迹反映了一个伸展的大地构造背景。已有年代学数据支持该区高温变质事件发生于二叠纪(270-280 Ma),与塔里木地幔柱活动的时间(~275 Ma)高度一致,这说明二叠纪高温变质事件可能与塔里木地幔柱有着密切的成因联系,因此,二叠纪地幔柱活动引起的幔源岩浆底侵和加热可能提供了阿尔泰南缘高温-超高温变质作用所需的热源。
[Abstract]:Altai orogenic belt is an important part of (CAOB) in Central Asian orogenic belt. High temperature muddy and mafic granulites are exposed in the southern margin of Altai orogenic belt. It is of great significance to determine its P / T trajectory for understanding the tectonic evolution history of the southern margin of Altai orogenic belt in the late Paleozoic. Based on the fine petrographic observation of Wuqagou muddy and mafic granulite samples in this area, it is shown that the mineral assemblage (M0) of argillaceous granulite before the peak period is biomica cordierite 卤spinel plagioclase quartz ilmenite, and the peak mineral assemblage (M1) is garnet cordierite biotite plagioclase quartz magnetite ilmenite 卤clinopyroxene 卤spinel feldspar, and the peak mineral assemblage (M1) is garnet cordierite plagioclase quartz magnetite ilmenite 卤clinopyroxene 卤spinel feldspar. The retrogression mineral assemblage (M2) is biotite plagioclase quartz 卤cordierite and so on. Before the peak period of mafic granulite, the minerals (M0) are mainly biotite and plagioclase, and the peak mineral assemblage (M1) is clinopyroxene hornblende plagioclase potassium feldspar quartz ilmenite magnetite. A small number of minerals such as hornblende and plagioclase (M2) are formed during retrogression. The P 鈮，
本文编号：2505912
[Abstract]:Altai orogenic belt is an important part of (CAOB) in Central Asian orogenic belt. High temperature muddy and mafic granulites are exposed in the southern margin of Altai orogenic belt. It is of great significance to determine its P / T trajectory for understanding the tectonic evolution history of the southern margin of Altai orogenic belt in the late Paleozoic. Based on the fine petrographic observation of Wuqagou muddy and mafic granulite samples in this area, it is shown that the mineral assemblage (M0) of argillaceous granulite before the peak period is biomica cordierite 卤spinel plagioclase quartz ilmenite, and the peak mineral assemblage (M1) is garnet cordierite biotite plagioclase quartz magnetite ilmenite 卤clinopyroxene 卤spinel feldspar, and the peak mineral assemblage (M1) is garnet cordierite plagioclase quartz magnetite ilmenite 卤clinopyroxene 卤spinel feldspar. The retrogression mineral assemblage (M2) is biotite plagioclase quartz 卤cordierite and so on. Before the peak period of mafic granulite, the minerals (M0) are mainly biotite and plagioclase, and the peak mineral assemblage (M1) is clinopyroxene hornblende plagioclase potassium feldspar quartz ilmenite magnetite. A small number of minerals such as hornblende and plagioclase (M2) are formed during retrogression. The P 鈮，
本文编号：2505912
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