Petrogenesis of the Mayo-Darley tin formations,anorogenic complex of the Cameroon Line:implication for tin deposit  

作　　者：Ndema Mbongué Jean Lavenir Ndongfong Edson Fuh Emmanuel Eseya Mengu Junior 

机构地区：[1]Department of Geology,Faculty of Sciences,University of Buea,P.O.Box 63,Buea,Cameroon [2]Department of Earth Sciences,Faculty of Sciences,University of Yaounde I,P.O.Box 812,Yaoundé,Cameroon

出　　处：《Acta Geochimica》2023年第4期704-725,共22页地球化学学报（英文）

摘　　要：The Mayo-Darley massif is an anorogenic complex of the Cameroon Line that has a mantle origin.Tin-bearing rocks were analyzed by ICP-AES and INAA analytical methods.The purpose of this work was to provide new geochemical data for the Mayo-Darley tin formation and to understand its petrogenesis and the origin of tin mineralization.The Mayo-Darley tin deposit is made up of tin-granite,and tin-greisen,greisenification was developed on the borders of quartz dykes.These rocks belong to the alkaline series and were classified into acid(SiO2-=61.6%–73.8%;65.4%–98%respectively)and basic(42.9%–47%SiO_(2))rocks.They showed enrichment in HSFE,LILE,Ga/Al and chondrite normalized REE patterns indicating LREE enrichment relative to HREE with a negative Eu anomaly,only sample SB8 of tin-granite showed Eu/Eu*=1.11.Rocks display metaluminous,peralkaline,peraluminous,ferroan,high-K calc-alkaline to shoshonitic,alkalic to calcic affinity,and crystallized at800°C.The chemistry of this deposit reflects the primary composition of granite,quartz monzonite,gabbro,and foid gabbro.This complex experienced multi-stage sub-solidus hydrothermal fluid reactions and shows variable alteration of feldspars alkali mobility.The rocks are classified as A1-type granite,overlap with the OIB field,and were derived from a within-plate setting,similar to mantle non plumederived magmas.The origin of tin mineralization in MayoDarley has a complex evolution,tin mineralization was derived from hydrothermal and hydrogenous metal-rich deposits and shows Sn–Hf–Zr and Sn–Tl–Nb association.These new data confirm the complexity of the Mayo-Darley tin complex and elucidate the origin of tin mineralization.

关 键 词：Mayo-Darley MASSIF Cameroon Line Tingranite Tin-bearing GREISEN A1-type granite Sn–Hf–Zr Sn–Tl–Nb 

分 类 号：P618.44[天文地球—矿床学]