本文選題：西準(zhǔn)噶爾　切入點(diǎn)：謝米斯臺(tái)　出處：《中國地質(zhì)大學(xué)(北京)》2015年碩士論文

【摘要】：傳統(tǒng)上,新疆西準(zhǔn)噶爾謝米斯臺(tái)地區(qū)的火山巖地層被歸屬為泥盆系-石炭系。這種歸屬主要依據(jù)區(qū)域地層對(duì)比,缺乏確定性的科學(xué)依據(jù)。本文報(bào)道了該區(qū)火山巖地層的兩條剖面,并對(duì)區(qū)內(nèi)出露的主要火山巖類型進(jìn)行了詳細(xì)描述。根據(jù)火山巖地層中巖石的不整合接觸關(guān)系、巖石組合及蝕變特征將其分為兩套不同時(shí)代的火山巖。在此基礎(chǔ)上,提供了代表性火山巖的鋯石U-Pb測年結(jié)果。提出謝米斯臺(tái)火山巖的時(shí)代(423.6-394.1Ma)屬于晚志留世-早泥盆世而不是中晚泥盆紀(jì)-石炭紀(jì)。晚志留世火山巖主要為安山巖和英安巖,夾少量火山凝灰?guī)r和蝕變砂巖。下泥盆統(tǒng)的組成巖石主要為安山質(zhì)-英安質(zhì)火山碎屑巖,夾有大量砂礫巖。該區(qū)地層的產(chǎn)狀總體南傾構(gòu)成一個(gè)單斜。此外探討了該區(qū)火山巖地層的大地構(gòu)造歸屬及其時(shí)空聯(lián)系性,認(rèn)為謝米斯臺(tái)火山巖是東哈薩克斯坦博什庫爾-成吉斯早古生代巖漿弧向東的延伸,可與東西兩側(cè)的火山巖地層構(gòu)成一個(gè)連續(xù)的晚志留世-早泥盆世火山巖帶。謝米斯臺(tái)古生代火山巖的Si O2含量多數(shù)56%,其Al2O3含量較高,多數(shù)具有高鉀鈣堿性、準(zhǔn)鋁質(zhì)-過鋁質(zhì)的特點(diǎn)。在主量元素哈克圖解中Ti O2、Al2O、Ca O、Mg O、TFe O和P2O5都與Si O2呈現(xiàn)負(fù)相關(guān)的趨勢�；鹕綆r的LREE相對(duì)于HREE略顯富集,Eu無明顯負(fù)異常。微量元素Rb、K等大離子親石元素為正異常,高場強(qiáng)元素Nb、Ta、P和Ti的負(fù)異常以及構(gòu)造判別圖解都顯示該地區(qū)火山巖來源于俯沖環(huán)境。結(jié)合已報(bào)道的火山巖年齡(435Ma-391Ma),認(rèn)為謝米斯臺(tái)地區(qū)主體為博什庫爾-成吉斯早古生代巖漿弧向東的延伸部分,同時(shí)又復(fù)合有少量扎爾瑪-薩吾爾晚古生代巖漿弧。謝米斯臺(tái)地區(qū)火山巖源于大洋巖石圈向下俯沖,脫水產(chǎn)生的富集大離子親石元素的流體以及洋殼熔融產(chǎn)生的中酸性熔體進(jìn)入地幔楔造成地幔部分熔融,巖漿在上升的過程中由于同化混染或地殼熔融而加入大陸地殼的物質(zhì)并經(jīng)歷一定的巖漿結(jié)晶分異作用而成。巖漿起源深度約為8km-33km,并且晚古生代的火山巖巖漿起源深度略深于早古生代巖漿。
[Abstract]:Traditionally, the volcanic strata in the West Junggar, Xinjiang, are classified as Devonian Carboniferous. This attribution is mainly based on regional stratigraphic correlation. This paper reports two sections of volcanic strata in this area and describes in detail the main types of volcanic rocks exposed in this area. The rock assemblages and alteration features divide them into two sets of volcanic rocks of different ages. The zircon U-Pb dating results of typical volcanic rocks are provided. It is suggested that the age of Shermisi volcanic rocks (423.6-394.1 Ma) belongs to late Silurian and early Devonian rather than middle and late Devonian to Carboniferous. The late Silurian volcanic rocks are mainly andesite and dolomite. A small amount of volcanic tuff and altered sandstone. The rocks of the Lower Devonian are mainly composed of Anshanian and Anshanian volcanic clastic rocks. The occurrence of strata in this area is generally southward inclined to form a monocline. In addition, the geotectonic attribution and space-time connection of volcanic strata in this area are discussed. It is considered that the shemis platform volcanic rock is an extension of the early Paleozoic magmatic arc eastward from Boshkul to Chungis in East Kazakhstan. A continuous late Silurian to early Devonian volcanic rock belt can be formed from the volcanic strata on both sides of the east and west. The Sio 2 content of the Cenozoic volcanic rocks of the Shermisi platform is 56%, its Al2O3 content is relatively high, and most of them have high potassium calc alkalinity. The characteristics of quasi-aluminite-peraluminite. In the Huck diagram of the principal element, TIO _ 2AL _ 2O _ 2, Ca, O, O, Fe, O _ (TO) and P2O5 are negatively correlated with Sio _ 2. The LREE of volcanic rocks is slightly less negative than that of HREE in enrichment of EU, and the trace element RB _ (K) is larger than that of Fe _ (2) O _ (2) O _ (2) O _ (2) O _ (2) O _ 2. The child lithophile element is positive anomaly, The negative anomalies of the high field strength elements NbPand Ti, as well as the tectonic discriminant diagrams, show that the volcanic rocks in this area originated from the subduction environment. Combined with the reported volcanic age of 435 Ma-391Ma, it is considered that the main body of the Shemis platform is Boshkur-early Genghis Paleo. The eastward extension of the Cenozoic magmatic arc, At the same time, there are a small amount of late Paleozoic magmatic arcs in Zarma-Savour. The volcanic rocks in the Shemistai area originated from the downward subduction of the oceanic lithosphere. Fluids enriched in large ion lithophile elements from dehydration and intermediate-acid melts from ocean crust melting into the mantle wedge lead to partial mantle melting. In the process of magma rising, the materials added to the continental crust due to assimilation or crustal melting are formed by certain magmatic crystallization differentiation. The origin depth of magma is about 8km-33km, and the magmatic origin of late Paleozoic volcanic rocks is about 8km-33km. The depth is slightly deeper than the early Paleozoic magma.
【學(xué)位授予單位】：中國地質(zhì)大學(xué)(北京)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：P588.14

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本文編號(hào)：1656479