地质学报2018，Vol.92Issue(1)：41-64,24.
北淮阳汞洞冲铅锌矿区石英正长斑岩成因
Petrogenesis of Quartz Syenite Porphyry in the Gongdongchong Pb-Zn Deposit, North Huaiyang Belt
摘要
Abstract
The Gongdongchong Pb-Zn deposit,located in the western part of North Huaiyang zone (Anhui section),is the largest Pb-Zn deposit in the Dabie Orogen at present.The deposit is a typical cryptoexplosive breccia type,and ore-forming fluid shows features of magmatic origin.Field investigation indicates that cryptoexplosion has a genetic link with the quartz syenite porphyry cropped out in the Sunchong area.LA-ICPMS U-Pb dating of two zircon samples from the Sunchong quartz syenite porphyry yields two ages of 128.4 ± 1.3 Ma and 129.2 ± 1.2 Ma,suggesting that it was the result of early Cretaceous magmatism.The Sunchong quartz syenite porphyry has high SiO2 (62.04％ ～69.30％),K2O (4.54％～7.16％),ALK (K2O+Na2O=8.76％～10.01％) and high K2O/Na2O ratios ranging from 0.94 to 2.86,A/NK=1.17～1.97,and A/CNK=1.03～1.59,suggesting that it can be grouped into weak to strong peraluminous rock.The rock is enriched in LILE such as Rb,Th,U,Pb,and depleted in HFSE such as Nb,Ta,P,Ti.The Sunchong quartz syenite porphyry has highly enriched Sr-Nd-Pb-Hf isotopic compositions:87Sr/86Sr(t) =0.71129～0.71323,εNd (t) =-10.8 to-9.8,206Pb/204 Pb(t) =17.495～17.891,207Pb/204pb(t) =15.526～ 15.593,208Pb/204 Pb(t) =38.257～38.547,most zircon εHf(t) values from-17.1 to-10.4.This study,combined with geochemical analysis of the Sunchong quartz syenite porphyry,indicates that the magmatic source of the Sunchong quartz syenite porphyry should be similar to that the upper part of three-layer crustal structure in the Dabie orogen with addition of minor mantle material,which is represented by the gneiss in the central-south Dabie belt.The widely spreading Paleozoic black shale in the South China Block,which subducted into deep crust in the North Huaiyang belt,may constitute an ideal source region for the ore-forming magmatic rocks.关键词
锆石U-Pb年龄/Sr-Nd-Pb-Hf同位素/石英正长斑岩/汞洞冲/北淮阳/大别造山带Key words
zircon U-Pb dating/Sr-Nd-Pb-Hf isotope/quartz syenite porphyry/Gongdongchong/North Huaiyang belt/Dabie orogen引用本文复制引用
刘晓强,闫峻,王爱国..北淮阳汞洞冲铅锌矿区石英正长斑岩成因[J].地质学报,2018,92(1):41-64,24.基金项目
本文为国家自然科学基金项目(编号41272074)、中国地质调查局地质矿产调查评价专项(编号12120113067800)资助的成果. （编号41272074）
