粵西福湖嶺加里東混合巖-花崗巖形成溫度研究
發(fā)布時間:2018-03-24 11:35
本文選題:欽-杭結(jié)合帶 切入點:福湖嶺剖面 出處:《巖石學報》2017年03期
【摘要】:欽-杭結(jié)合帶南段廣泛發(fā)育加里東期的混合巖和混合花崗巖。研究這些混合巖和混合花崗巖形成的P-T條件,不但有助于了解加里東造山階段本區(qū)地殼內(nèi)部的溫度特征,對于花崗巖漿形成以及大陸流變等理論問題的研究也有重要意義。本文討論的福湖嶺剖面位于欽-杭結(jié)合帶南端,為一海邊巖壁,其上出露分帶清晰的加里東期混合巖-混合花崗巖,自上而下依次為斑點狀混合巖、條紋狀混合巖、窄條帶狀混合巖、寬條帶狀混合巖及混合花崗巖。作者在野外對剖面上不同類型的巖石進行了影像采樣,在計算機上對采集影像樣品進行處理,在統(tǒng)一閥值下轉(zhuǎn)換成代表淺色體(熔體)和暗色體(未熔巖石或熔渣)的黑白影像,并統(tǒng)計淺色體的含量百分比(熔體比)。將由此得到的各類巖石熔融比數(shù)據(jù)投到用Winkler and von Platen(1961)的硬砂巖熔融實驗數(shù)據(jù)構(gòu)成的溫度-熔體比曲線圖上,獲知該剖面混合巖的形成溫度在630~705℃之間,原巖的熔斷溫度("臟"花崗巖漿生成溫度)為705℃,巖石熔融時(439~445Ma)剖面的埋深大體處于當時地表以下7km左右。本文結(jié)合福湖嶺剖面地質(zhì)研究和巖石熔融實驗數(shù)據(jù)建立的"熔融溫度計",為混合巖-混合花崗巖形成溫度的測定提供了一種新方法,不僅適用于福湖嶺,也可用于其它地區(qū)。
[Abstract]:Caledonian migmatite and migmatite are widely developed in the southern part of the Qinghang combined belt. Studying the P-T conditions of these migmatite and migmatite is not only helpful to understand the temperature characteristics of the crust in the Caledonian orogenic stage. It is also important to study the formation of granitic magma and continental rheology. The Fuhuling section discussed in this paper is located at the southern end of Qinghang joint zone and is a seaside rock wall. The clear Caledonian migmatite-migmatite in the upper outcrop zone is followed by speckled migmatite, striped migmatite, narrow stripe migmatite, and narrow stripe migmatite from top to bottom. Wide banded migmatite and mixed granite. In the field, the authors sampled different types of rocks in the profile and processed the image samples on the computer. Converted to black and white images representing light-colored bodies (melts) and dark ones (without lava or slag) at the unified threshold, And the percentage of the content of the light-colored body (melt ratio) is calculated. The obtained melting ratio data of various kinds of rocks are put into the temperature-melt ratio curve of the hard sandstone melt experiment data of Winkler and von platform. The formation temperature of migmatite in this section is between 630 鈩,
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