The Geological Features And Wall-rock Alteration Of The Tin Deposit Related To A-type Granite From Kalamaili, North Xinjiang

Kalamaili region, east of the Junggar, north Xinjiang, develops series of tindeposits, the studies about petrology and geochemistry on the ore-forming granitesshow that granites with high silicon, alkali, low aluminum and poor characteristics ofcalcium and magnesium, have higher differentiation degree, which belong to thealuminum A-type granite. Further systematic studies on tin deposit geologicalcharacteristics and mineralization alteration zone which related to A-type granite,including Kamusite, Ganliangzi, Belekuduke and Sareshike four tin deposits, showthat Kalamaili tin ore belt developes strong alteration. Summed up the depositalteration zoning characteristics as follows: Kamusite deposit: fine grainedgraniteâ†'greisenization fineâ†'grained graniteâ†'tin containing quartz vein;Ganliangzi deposit: fine grained graniteâ†'tin containing greisenâ†'tin containingsilicification vein; Belekuduke deposit: biotite alkali-feldspar graniteâ†'alteration finegrained graniteâ†'tin containing greisen; Sareshike deposit: fine grained iron sodiumamphibole graniteâ†'granite porphyryâ†'tin containing quartz vein.The calculation result of chemical composition migration quantity in thealteration zone, shows that elements in the migration patterns of Deposits’ alteredbelt:from the surrounding rock to altered rock to ore body,SiO2has been in a state ofmoving in; Fe2O3generally in a state of emigration, or moving in before they are out;Na2O, K2O, F, Cl in a state of relatively frequent bigger migration with no constantmigration patterns; Al2O3, MnO, MgO, CaO, P2O5was obviously brought in thenbrought out, and the migration of F and Cl was the largest, which suggesting that theliquids was rich in SiO2, alkali and volatiles, and the mineralization took place in anoxidation environment. Alkali metasomatism was on going throughout theore-forming process, active elements such as Na, K, F, Cl, Ta, Nb et al., were closelyassociated with tin mineralization.The deposit metallogenetic mechanism in this area is: magma isolated rich Snore hydrothermal fluid in the late magmatic evolution, and hydrothermal fluid risedalong the fracture or fracture zone of rock mass, arousing intense alteration in the surrounding rock. Alkali metasomatism and other physical and chemical conditionchanges made the cassiterite enriched then precipitatined, eventually in theappropriate space mineralizede. The formation of ore deposits in the area is the resultof rich alkali granitic magma fully evolved then altered. The deposit type is quartzvein+greisen type deposit, according to the genesis belongs to hypabyssalintermediate high temperature hydrothermal deposit.