LA-ICP-MS Zircon U-Pb Dating of Syenite Granite in the Lailishan Tin Deposit of Western Yunnan Province and Its Geological Significance
详细信息
- 责任者：Jin Canhai (Chengdu Institute of Geology and Mineral Resources ; Chengdu 610081 ; China) ; Fan Wenyu
- 刊名：Acta Geologica Sinica
- 出版年：2013
- 卷期：87(9)
- 关键词：锡矿 ; tin ores ; 正长花岗岩 ; syenogranite ; 云南 ; Yunnan Province
- 页码：p.1211-1220
- 图表：9 illus., 4 tables, 45 refs.
- 分类号：1001
- issnNo：ISSN0001-5717
- isbnNo：CN11-1951/P
摘要
Lailishan tin deposit is located in the Tengchong-Lianghe tin metallogenic subzone of western Yunnan tin metallogenic zone,and is between Nujiang suture zone and Myitkyina suture zone in Tengchong block south of Sanjiang tectonic zone.Tin ore bodies occur in both the Mid-Carboniferous Siguangping Group fracturing zone and syenite granite contact zone in the southeastern margin of the Lailishan complex.Tin mineralization was closely related to syenite granitic magma activity.The syenite granite has SiO2content of 76.00%77.10%,Al2O3 content of 12.62%13.50%,TFeO/MgO of 9.7972.50,suggesting rich Si,Al,and high Fe and low Mg.A/CNK of 1.021.32,K2O/Na2O of 1.422.26,and Rittman index（δ）of 1.402.29,show the rock belongs to the high-K calc-alkaline and peraluminous granite series.The rocks are characterized byΣREE=98.68×10-6191.89×10-6,strong negative Eu anomalies（δEu= 0.070.10）,very weak Ce anomalies（δCe= 0.630.99）,LR/HR=0.190.69,（La/Yb）N =0.311.24,with no clear differentiation in light and heavy rare earth elements,severe depletion of P and Ti,depletion of Ba,K and Nb,enrichment of La,Zr,and Th.All this results indicate it is crustal sourced Stype syn-collisional granite.LA-MC-ICP-MS U-Pb method yielded a diagenetic age of 52.530.29 Ma（MSWD=1.8）,indicating it was the product of Middle Eocene India-Eurasia collisional orogeny,which resulted in emplacement and cooling of partially melting magma consisting of upper crustal shale rocks due to extensive compression and thickening under the condition of unsaturated water.Metallogenic material of the Lailishan Tin deposit originated from surrounding rocks and granite,and metallogenic fluids were mainly magmatic water.The age of metallogenic is consistent with the diagenetic age of syenite granite.Tin ore reflects the response to the magmatic activities during Early Himalayan India-Eurasia collisional orogeny,and indicates that there was at least one tin metallogenesis closely related to the Lailishan syenite granite in this area 51.154Ma ago.
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