阿拉善地块晚古生代构造演化新模式：来自岩浆岩和沉积岩的记录

本文根据阿拉善地块岩浆岩和沉积岩的记录分析，结合造山带岩石圈演化，提出阿拉善地块随着古亚洲洋在晚志留世末闭合，发生弧-陆或陆-陆碰撞、以及与相邻地块的碰撞，使陆壳得到广泛加厚；晚古生代时期以伸展为特征，早石炭世造山带岩石圈初始垮塌，致使阿拉善地块北部珠斯楞—杭乌拉带由泥盆纪相对稳定的被动陆缘，转为活动陆缘，并形成一套前弧碎屑岩-火山岩沉积；晚石炭世乌力吉—宗乃山—沙拉扎山带岩石圈初始垮塌、诺尔公—红古玉林带造山带岩石圈初始垮塌，由此构成阿拉善地块岩石圈部分垮塌，使中南部广泛区域沉降，形成一套后弧环境的海相碳酸盐-碎屑岩沉积岩石组合，并伴随同时期的辉长岩等基性岩体侵入；二叠纪造山带岩石圈完全垮塌，大规模软流圈上涌物质和热，使俯冲的洋壳物质、加厚下地壳混合物质、交代岩石圈地幔衍生新生物质等被加热熔融，形成高（超）钾岩浆储库。早二叠世，因侧向强迫重力翻转或受塔里木早二叠世地幔柱活动的触发，导致高（超）钾质岩浆沿珠斯楞、乌力吉、诺尔公陆壳中的岩石圈不连续挤出，以气球膨胀式短时、快速侵位，形成以珠斯楞、乌力吉、诺尔公为代表的二叠纪巨量花岗岩带，该时期也应该是阿拉善地块最重要的大规模成矿时期。阿拉善地块是华北克拉通的组成部分，至今在其南部依然保留着大于200 km厚的岩石圈。阿拉善地块在早古生代时期汇聚，伴随古亚洲洋、祁连洋的形成、演化与消亡及与华北地块相互作用，使阿拉善地块被“破坏”；晚古生代时期伸展，伴随造山带岩石圈垮塌被“肢解”，总体上属于西部“华北克拉通破坏”范畴，显生宙以来的构造-岩浆事件，是西部“华北克拉通破坏”的响应。

A new model of Late Paleozoic tectonic evolution in the Alxa Block： Records from magmatic and sedimentary rocks

Based on the record analysis of magmatic and sedimentary rocks in the Alxa Block， combined with the evolution of the orogenic-type lithosphere. It is proposed that the Alxa Block underwent arc & land or land & land collision with the closure of the ancient Asian Ocean at the end of the Late Silurian， as well as collision with adjacent blocks， resulting in widespread thickening of the continental crust in this papper； In the Late Paleozoic era， characterized by extension， the orogenic-type lithosphere in Early Carboniferous initially collapsed， causing the northern part of the Alxa Block to transform from a relatively stable passive margin in the Devonian to an active margin， and forming a set of forearc clastic and volcanic sedimentary rocks； The initial collapse of the orogenic-type lithosphere in the Uliji-Zongnaishan-Salazar belt and Noergong-HongguYulin belt during the Late Carboniferous formed a partial collapse of the lithosphere in the Alxa Block， causing widespread subsidence in the central and southern regions， forming a set of marine carbonate clastic sedimentary rock combinations in a backarc environment， accompanied by the intrusion of basic rock masses such as gabbros during the same period； The complete collapse of the Permian orogenic-type lithosphere resulted in the upwelling of materials and heat from the large-scale asthenosphere， which heated and melted the subducted oceanic crust material， thickened lower crustal mixed material， and new biomass derived from the metasomatic lithospheric mantle， forming a high （super） K magma reservoir. In the Early Permian， due to lateral forced gravity overturning or triggering by the activity of the Tarim Early Permian mantle plume， high （super） K magma was extruded along the lithosphere discontinuties of the Zhusileng， Uliji， and Nuoergongin continental crust ， and rapidly invaded in a balloon expansion manner， forming a Permian massive granite belt which represented by Zhusileng， Uliji， and Nuoergong. This period should also be the most important large-scale mineralization period for Alxa Block. The Alxa Block is a component of the North China Craton， and to nowadays， a lithosphere thicker than 200 km is still preserved in its southern part. The Alxa Block converged during the Early Paleozoic era， accompanied by the formation， evolution， and extinction of the ancient Asian Ocean and Qilian Ocean， as well as their interaction with the North China Block， resulting in the destruction of the Alxa Block； During the Late Paleozoic era， the extension was accompanied by the collapse of the orogenic-type lithosphere， which was "dismembered". Overall， it belongs to the category of "North China Craton Destruction" in the west. The tectonic-magmatic events since the Phanerozoic era are a response to the "North China Craton Destruction" in the west.