Confirmation of Indosinian Age of the Niulanling Granite from Limu Orefield, Guangxi Province and Its Significance
详细信息
- 责任者：Zhang Huaifeng (State Key Laboratory for Mineral Deposit Research ; Department of Earth Sciences ; Nanjing University ; Nanjing 210093 ; China) ; Lu Jianjun
- 刊名：Geological Journal of China Universities
- 出版年：2013
- 卷期：19(2)
- 关键词：深成岩体 ; plutons ; 铀—铅计时 ; U-Pb dating ; 广西 ; Guangxi Province
- 页码：p.220-232
- 图表：illus., 3 tables, 49 refs.
- 分类号：0801
- issnNo：ISSN1006-7493
- isbnNo：CN32-1440/P
摘要
The samples from the Niulanling fine-grained and porphyritic granites have been analyzed for zircon U-Pb ages and whole rock geochemical compositions to discuss the emplacement age,genetic type,source and relationship with the mineralization.LA-ICP-MS zircon U-Pb dating results of the two granite samples indicate that the granites formed in the Late Indosinian period with weighted average age of(223.6±1.7) Ma and(223.7±1.7) Ma,respectively.The granites are rich in SiO 2,K 2 O,Na 2 O and P 2 O 5 and poor in CaO,MgO and TiO 2.The granites are strongly peraluminous with the A/CNK values changing from 1.08 to 1.31.CIPW-normative calculation gives 1.6%-4.5% corundum.Chondrite-normalized REE diagrams of the granites have slightly right-leaning shape with strong negative Eu anomalies and δEu values vary from 0.01 to 0.05;The granites are enriched in LILE(Cs,Rb,K) and HFSE(U,Pb,Hf,Ta),but are relatively low in Ba,Sr and Ti.The zircon saturation temperatures(t zr) are from 631 to 681 ℃,which are lower than the averageing value of S-type granites.The(1947±23) Ma inherited zircon indicates that the source region of the granite is mainly Late Palaeoproterozoic crustal materials.The inherited zircon of(248±4) Ma suggests an addition of the Early Indosinian magma in the formation of the granites.The geological and geochemical characteristics of the granites show that the granites could provide W and Sn for the W-Sn mineralization in the Niulanling district and there might be mineralization of about 224 Ma in this area.The Indosinian mineralization should be the key target in the Limu district and very important even for western Nanling Range as a whole in the further ore-prospecting work.