The Study On The Spodumene Deposit Geological Features And Genesis In South Of Rongxuka,Daofu County,Sichuan Province

The western area of Sichuan, China is the important metallogenic province of pegmatite deposit which has famous such as Jiajika super large lithium deposit, Keeryin super large beryllium deposit and Danba large muscovite deposit,are all located at Songpan-Ganzi orogenic belt. Number of rate metal pegmatite deposits are discovered in this area. The research degree of pegmatite deposit is low because of the influence of geographical conditions and the whole industrial backwardness. Rare metal deposits in China is relatively rich, and with the development of the rare metal, especially the electronic industry, lithium battery industry in our country, the demand for rare metals especially spodumene ore will be more and more. So in the coming decades, the exploration and development of spodumene ore deposit will enter a exuberant period.South Rongxuka spodumene ore deposit is located in the junction of Kangding county,Yajiang county and Daofu county. Geographical coordinates: longitude 101 ° 12 ’45’- 101 ° 18 ’00 ", north latitude 30 ° 26’ 15-30 ° 29 ’00 ".The elevation is 3200m~4500m.This region is belong to the deeply cut high mountain between the Sichuan basin and Sichuan-Tibet plateau. This spodumene ore deposit is a typical rare metal granite pegmatite deposit.This article rely on the “Reconnaissance Survey on spodumene ore of South Rongxuka,Sichuan province Daofu county ”project which is from the Land and Resources Department of Sichuan Province, choose the spodumene ore deposit as the research object. The author summarizing the pegmatite and rare metals pegmatite research results and related data from the predecessors, on the basis of a lot of detailed geological work, studies the spatial distribution relationship of orebody, strata,lithology,structure and magmatic rock. Basically find out the main composition and the structure characteristics of the ore through the identification of the light slice and thin slice. Preliminary discussed the geological characteristics and genesis of the deposit at study area through the study of geochemistry. The following key knowledge and results:(1)Study area is located the southeast of Songpan-Ganzi orogenic belt, the west of Xianshuihe fracture, in the Yajiang domal plasmid group, on the Yajiang arc tectonite. The extension of late Songpan-Ganzi orogenic belts caused the appreared of Yajiang hot rise fields is shallow level “thermal uplift” stretch structure because of the rise deep molten granite as the center.So fornix is the main structure characterize in this area, and Rongxuka fornix and Jiajika fornix were formed.Affected by the Himalayan Xianshuihe fault, the other faults are northwest. With the orogeny occurred,granite magmatism is strong,frequent and massive since late Paleozoic, Mesozoic in particular. There were formed numerous granite rock types which has a extensive distribution and proves the material sources of rare ore.(2)The main exposure strata comes from upper Triassic,Xinduqiao group(T3xd) which composed of two-mica-quartz schist containing staurolite andalusite, schist containing garnet andalusite staurolite, muscovite microcrystalline schist containing garnet with a little lenticular hornfels quartz siltstone. The study area is low pressure metamorphic zone, and the metamorphic formation is deposited of Triassic silty and sandy flysch. It is called shallow “thermal uplift” by Hou Liwei etc.(1994,1996), and there is S-type granite and pegmatite in it’s core part. And the increasing metamorphic zone such as biotite zone, garnet zone, andalusite zone, staurolite zone, fibrolite zone are ring distributed in Triassic metamorphic strata. Triassic formation of study area has been through superimposed of metamorphism with many times and multi-type. In the early days, with the development of Indosinian period tectonic movement, regional layers are generally experienced regional metamorphism which is just greenschist facies, namely early syntectonic metamorphism. The metamorphism agents is given priority to with stress, heat. The stage of metamorphism type formed the regional level of sericite chlorite metamorphic belt.(3)The intermediate acid intrusive rocks in Yajiang super unit of Yajiang tectonic magmatic zone, mainly adamellite, biotite diorite, adamellite quartz diorite and plenty of granite pegmatite dyke which is particular development. There is rich rare metal inside the pegmatite dike which produced the lithium spodumene ore. The ore-occurred strata position on upper Triassic,Xinduqiao group with fissure filling. This group is middle-low metamorphic rock system such as biotite quartz schist, two-mica-quartz schist, andalusite staurolite quartz schist formed by regional metamorphism and contact metamorphism. The study area developed a variety of joint and fracture, it’s tendency is 300°~310°, dip 60°~70°. The most important is NE steep shear fracture which constitute the host space of granite pegmatite type rare metal ore.(4)The rare metal granite pegmatite genetic in study area is divided into the following five types. Ⅰ,microcline type. Ⅱ,microcline sodium feldspar type. Ⅲ,sodium feldspar type. Ⅳ,sodium feldspar spodumene type. Ⅴ,albite lithium mica type. The formation of all types are in a certain stage of pegmatite melting solution unified evolution process. Therefore there is a certain degree of inheritance development characteristics of the adjacent type. So the transition characteristics and the transitional type is inevitable. The rare metal granite pegmatite type deposit with industrial value generally distributed in albite spodumene pegmatite type belt(Ⅳ). The useful group is spodumene, and the associated element is beryllium, niobium and tantalum which have high grad, and it is the main prospecting direction of rare metal in study area.(5)Besides of lithium, other rare metal elements such as beryllium, niobium, tantalum and rubidium also got full enrichment. Lithium is mostly in the spodumene and the single mineral concentration factor is 96.42%. And it is secondly in the lithium mica, a little into the forming minerals lattice quality and same. Beryllium is also the main associated components of this deposit and mostly enriched in the fine grain beryl occurred in metasomatic period. In addition, tin element as well as comprehensive recycling useful components. The main rock forming elements such as silicon, aluminum potassium, sodium and iron of the pegmatite dike are relatively stable, the relationship with the rare metal mineralization degree is not obvious.