【作者】 申文环；

【导师】 胡能高；

【作者基本信息】 长安大学 ， 矿物学、岩石学、矿床学， 2007， 硕士

【摘要】 塔塔楞岩体是位于柴北缘造山带的古生代环斑花岗岩体,前人对该岩体的研究较少,塔塔楞岩体与典型环斑花岗岩在岩相学特征上是相似的,如环斑结构和矿物生长世代方面,但在地球化学特征和构造环境等方面,两者又截然不同。本文通过对塔塔楞岩体的岩相学、矿物学及地球化学的分析研究,再与秦岭造山带的鹰峰和沙河湾环斑花岗岩体及芬兰经典环斑花岗岩体进行对比分析,进而探讨塔塔楞岩体的成因及其构造环境,这对研究古生代柴北缘造山带的形成演化具有重大意义。本文在详细的野外调查基础上,对塔塔楞岩体进行了岩相学、矿物学及地球化学等方面的研究,取得了以下认识:1.塔塔楞环斑花岗岩体是由环斑花岗岩、钾长花岗岩、二长花岗岩及斑状二长花岗岩等岩石构成的一套花岗质岩石组合,主体岩性为环斑花岗岩,具典型的环斑结构,与典型的环斑花岗岩相一致。而在岩石组合上,该岩体没有双峰式岩石组合的特征,这与典型的环斑花岗岩是不同的。2.在主量元素上,塔塔楞岩体显示出了碱性、高钾、过铝及富铁的特征;在稀土元素特征上,为Eu负异常明显的轻稀土富集型;在微量元素特征上,显示出富集Rb、Th、K、Nd、Tb等,相对亏损Zr、Hf、Y、Yb等高场强元素,而显著亏损Ba、Nb、Ta、Sr、P、Ti等元素,这一微量元素特点与碰撞型花岗岩非常吻合;与秦岭—昆仑造山带的鹰峰和沙河湾环斑花岗岩的地球化学特征相比,塔塔楞环斑花岗岩与鹰峰环斑花岗岩更为接近。3.塔塔楞岩体各岩石类型均为A2型花岗岩,说明塔塔楞岩体来源于陆壳,且岩浆直接起源于经历了陆—陆碰撞作用的陆壳,由上地壳物质熔融产生,各岩石类型是在壳源岩浆的不同分异阶段形成的。4.塔塔楞岩体的时代为古生代,锆石SHRIMP年龄为441.7±6.4Ma,这个时间与古生代柴北缘地区加里东期造山作用几乎同时;各岩石的形成与板块深俯冲和陆陆碰撞作用有密切的关系;高压-超高压变质带与塔塔楞岩体的形成时代大体相当,且微量元素特征表明塔塔楞岩体形成于同碰撞构造背景下,说明其在板块深俯冲和陆陆碰撞的同时期侵入;由此,可以将塔塔楞岩体看作是柴北缘古生代碰撞造山的标志,之后,柴北缘向造山期后转变,这对研究古生代柴北缘造山带的形成演化具有重大意义。更多还原

【Abstract】 The Tataleng body which is Paleozoic rapakivi granite is located in the North Qaidam orogenic belt, and Predecessors study less on Tataleng body. Tataleng body and typical rapakivi granite is similar in petrography, such as rapakivi structure and the growth of generation, But in geochemical characteristics and tectonic aspect, the two is very different. This paper, according to analysis and research in petrography, mineralogy and geochemical of Tataleng body, compared with Yingfeng, Shahewan of Qinling orogenic belt and Finland classic rapakivi granite body, Then discusses the origin and tectonic environment of Tataleng body, this research on the formation and evolution of North Qaidam Paleozoic orogenic belt is of great significance.Based on the detailed field works, analysis of petrology, geochemistry and geochronology of the Tataleng body, we can draw several main conclusions as bellows:1. The Tataleng rapakivi granite body is a suit of granitic rock which is comprised of rapakivi granite, moyite, monzonitic granite and porphyritic monzonitic granite, the majority of Tataleng body is rapakivi granite, which has the typical rapakivi structure, is consistent with the typical rapakivi granite. But in magmatic association, this body does not have the character of bimodal magmatic association, which is different from the rapakivi granite.2. In host element, tataleng body has the features of alkali, high value of K, over Al-saturation, and enrichment of Fe; In REE element, the body has the feature of obvious negative Eu anormaly, belonging to LREE enrichment type; In trace element, the body demonstrated the characters of concentrates Rb, Th, K, Nd, Tb, and relatively depleted in HFSE such as Zr, Hf, Y, Yb, but remarkably depleted in Ba, Nb, Ta, Sr, P, Ti, this trace element character of Tataleng body is extremely consist with the collision granite; Compares with geochemistry characteristic of Yingfeng and Shahewan rapakivi granite in Qinling-Kunlun orogenic zone, the Tataleng rapakivi granite is more similar to Yingfeng rapakivi granite.3. Every rock of The Tataleng body is A2-type granite, explained the Tataleng body originates from the continental crust, also the magma directly originned from the continental crust which has experienced the land-land collision function, fused from the substance of supracrust, various rock type was formed different differentiation stage of crustal magma. 4. The Tataleng body formed in Paleozoic Era, the zircon SHRIMP age is 441.7±6.4Ma, this time is nearly simultaneous with the Caledonian orogenesis of Paleozoic north Qaidam area; there was close relationship between the formation of various rocks with the deep subduction of tectonic plate and land-land collision functions; It is roughly quite between HP-UHP zone of metamorphism and the Tataleng body in there formation time, also the trace element characteristic indicated the Tataleng body formed in syncollision tectonic background, showing it intrusioned in that time of deep subduction of tectonic plate and land-land collision functions; From this, We might regard Tataleng body as the symbol of Paleozoic north Qaidam collision, afterwards, north Qaidam transforms to the postorogenic, all of this have great significance to studied formation and evolution of Paleozoic north Qaidam.更多还原