The Features And Genesis Of Tataleng Rapakivi Granite In North Qaidam Basin

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.