【摘要】：中亞造山帶內(nèi)東準(zhǔn)噶爾地區(qū)北西西-南東東走向的大型卡拉麥里斷裂帶,為野馬泉島弧與哈爾里克島弧之間的拼貼邊界,沿卡拉麥里蛇綠巖帶南緣出現(xiàn)。本文通過(guò)詳細(xì)的野外與室內(nèi)構(gòu)造分析表明,卡拉麥里斷裂帶經(jīng)歷了四期構(gòu)造活動(dòng)。第一期為晚石炭世中期的脆-韌性右行走滑活動(dòng),剪切帶內(nèi)較軟弱的板巖、砂板巖及淺變質(zhì)凝灰?guī)r內(nèi)出現(xiàn)了密集的面理化帶及張裂脈,而在泥灰?guī)r內(nèi)形成了糜棱巖。第二期為中二疊世晚期與三疊紀(jì)末的脆性逆沖活動(dòng),主要表現(xiàn)上盤(pán)向南的逆沖,疊加的逆沖斷層一方面沿著早期陡立的剪切帶面理發(fā)育,另一方面以較緩的產(chǎn)狀切割剪切帶。第三期為晚侏羅世的脆性左行走滑活動(dòng),疊加在早期脆-韌性剪切帶與脆性逆沖斷層之上。第四期為古近系初的脆性逆沖活動(dòng),并帶有一定的右行分量。各類(lèi)地質(zhì)現(xiàn)象指示,晚石炭世中期卡拉麥里斷裂帶脆-韌性右行走滑剪切帶的形成溫度為250-300℃,與該區(qū)前二疊紀(jì)海相火山-碎屑巖的低級(jí)區(qū)域變質(zhì)作用和緊閉褶皺同時(shí)發(fā)生。這期變質(zhì)、變形也與區(qū)內(nèi)海退同時(shí)發(fā)生。這些現(xiàn)象表明該剪切帶是野馬泉島弧與哈爾里克島弧斜向碰撞的結(jié)果,并指示早期卡拉麥里洋盆向北俯沖。中二疊世晚期卡拉麥里斷裂帶第二期逆沖活動(dòng)是發(fā)生在該區(qū)后造山伸展之后,屬于陸內(nèi)變形,應(yīng)為中亞造山帶區(qū)域上一次中二疊世碰撞活動(dòng)導(dǎo)致的。作為準(zhǔn)噶爾盆地東北緣的一級(jí)邊界斷裂帶,卡拉麥里斷裂帶控制和影響了準(zhǔn)東地區(qū)盆地的形成和演化。準(zhǔn)噶爾盆地形成于早二疊世的后造山伸展環(huán)境下。中二疊世,沿卡拉麥里斷裂帶及其南側(cè)山前大規(guī)模向盆地的逆沖活動(dòng),構(gòu)成了準(zhǔn)噶爾盆地東北緣的前陸沖斷構(gòu)造帶,盆地轉(zhuǎn)化為前陸型盆地。隨后在三疊紀(jì)期間,區(qū)內(nèi)構(gòu)造活動(dòng)較弱,盆地進(jìn)入穩(wěn)定沉積的坳陷階段。三疊紀(jì)末,沿卡拉麥里斷裂帶再次發(fā)生了逆沖活動(dòng)。這兩次逆沖活動(dòng)造成了陸梁隆起上一系列北西西-南東東向凸起與凹陷相間的盆地格局。早-中侏羅世期間,準(zhǔn)噶爾盆地又進(jìn)入坳陷階段。晚侏羅世,卡拉麥里斷裂帶在近東西向擠壓背景下發(fā)生了左行走滑活動(dòng),同時(shí)該期區(qū)域擠壓造成了盆內(nèi)東部隆起一系列近南北向的逆沖斷層與褶皺,從而呈現(xiàn)出近南北向凹陷與凸起相間的盆地格局。隨后在早白堊世該盆地又進(jìn)入穩(wěn)定沉積的坳陷階段。古近紀(jì)初,卡拉麥里斷裂帶在近南北擠壓背景下又發(fā)生了逆沖活動(dòng),該期擠壓造成了準(zhǔn)噶爾盆地東部隆起內(nèi)一系列近東西向的凹陷與凸起疊加在早期近南北向的凹陷與凸起之上,從而形成現(xiàn)今的“棋盤(pán)式”盆地構(gòu)造格局。
[Abstract]:The large Karamaili fault zone in the east Junggar area of the Central Asian orogenic belt is the collage boundary between the Nomaquan island arc and the Harrik island arc, which appears along the southern margin of the Kalamaili ophiolite belt. Through detailed field and indoor structural analysis, it is shown that the Karamaili fault zone has experienced four stages of tectonic activity. The first stage is the brittle-ductile right-lateral strike-slip activity in the middle of the late Devonian. In the shear zone, there are weak slate, sand slate and shallow metaphorical tuff, and dense facified zones and tensioned veins appear, while mylonite is formed in the marl. The second stage is the brittle thrust activity in the late Middle Permian and the end of Triassic, which mainly shows the southward thrust of the upper plate. On the one hand, the superimposed thrust fault develops along the surface of the early steep shear zone, on the other hand, it cuts the shear zone with a slow occurrence. The third stage is brittle left strike-slip activity in late Jurassic, which is superimposed on the early brittle-ductile shear zone and brittle thrust fault. The fourth stage is the brittle thrust activity at the beginning of Paleogene, and has a certain right-lateral component. All kinds of geological phenomena indicate that the formation temperature of the brittle-ductile right walking slip shear zone in the Karamaili fault zone in the middle of late Carboniferous is 250 擄300 鈩，

本文編號(hào)：2504356