Geology and origin of the post-collisional Narigongma porphyry Cu-Mo deposit, southern Qinghai, Tibet
Geology and origin of the post-collisional Narigongma porphyry Cu-Mo deposit, southern Qinghai, Tibet
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西藏青海南部纳日贡马碰撞后斑岩铜钼矿床地质及成因
DOI：
10.1016/j.gr.2013.07.012
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发表时间：
2014-09
影响因子：
6.1
通讯作者：
Wang, Zhaolin
中科院分区：
文献类型：
--
作者：
Yang, Zhusen;Tian, Shihong;Liu, Yingchao;Wang, Zhaolin
Narigongma是一种研究较少的富钼（~ 0.06 wt.%）青藏高原南部玉龙斑岩型铜钼Au带西北400 km处的碰撞后斑岩型铜存款矿床。纳日贡玛存款与玉龙带斑岩型矿床形成时代相近（43-40 Ma），但矿石组合不同。纳日贡玛存款与始新世花岗闪长岩和花岗岩侵入体有关，侵入二叠纪火山-沉积岩序列。一个~ 43.3 Ma的黑云母花岗岩岩株（P1斑岩）是始新世最早的侵入体，它本身被一些较小的~ 43.6 Ma的细粒花岗斑岩岩株（P2斑岩）和几个矿后石英闪长斑岩脉（~ 41.7 Ma）侵入。纳日贡玛的主要铜钼矿化与P1斑岩体有关。矿床周围的热液蚀变一般以同心带为特征，同心带的范围从内部钾质带向外到叶状和泥质蚀变带，以及外部青岩带。纳日贡玛深生成矿作用以钾质蚀变过程中的早期辉绿石沉淀和千枚蚀变过程中的晚期黄铜矿沉淀为特征。钼、铜成矿阶段的沉积是由温度降低引起的。P1斑岩在流体饱和之前发生了高度结晶，由于Mo的不相容行为，导致Mo在残余熔体中富集。而相容的Cu被结晶相隔离，形成高Mo/Cu岩浆热液，形成Mo ± Cu矿化组合。锆石εHf（t）值为+4.1 ~+7.9，表明岩浆来源于亏损源区。结合纳日贡玛斑岩的高SiO2、K2 O、低MgO、低相容元素丰度、稀土元素高度分馏模式等地球化学特征，表明该斑岩体的成因模式为混合成因。碰撞后成矿斑岩的形成经历了两个阶段：（1）含交代金云母的岩石圈地幔部分熔融，产生钾质-超钾质镁铁质熔体;（2）这些熔体在增厚的新生下地壳下底侵，触发下地壳部分熔融，产生成矿的高钾埃达克质岩浆。
Narigongma is a poorly studied Mo-rich (~ 0.06 wt.%) post-collisional porphyry Cu deposit located in southern Qinghai Province, Tibet, 400 km northwest of the Yulong porphyry Cu–Mo–Au belt. The Narigongma deposit has a similar age (43–40 Ma) to porphyry deposits in the Yulong belt, but different ore assemblages. The Narigongma deposit is associated with Eocene granodiorite and granite intrusions that were emplaced into a Permian volcanic–sedimentary rock sequence. An ~ 43.3 Ma biotite granite stock (P1 porphyry) is the earliest Eocene intrusion, and this was itself intruded by a number of smaller, ~ 43.6 Ma fine-grained granite porphyry stocks (P2 porphyry) and several post-ore quartz diorite porphyry dikes (~ 41.7 Ma). The main Cu–Mo mineralization at Narigongma is associated with the P1 porphyry. Hydrothermal alteration surrounding the deposits is generally characterized by concentric zones that range from an inner potassic zone outward to phyllic and argillic alteration zones, and an outer propylitic zone. Hypogene mineralization at Narigongma was characterized by early-stage precipitation of molybdenite during potassic alteration and late-stage deposition of chalcopyrite during phyllic alteration. Deposition of both the Mo and Cu mineralization stages was caused by decreasing temperature. A high degree of crystallization of the P1 porphyry occurred prior to fluid saturation that produced Mo enrichment in the residual melt due to the incompatible behavior of Mo. However, compatible Cu was sequestered by the crystallizing phases and resulted in the generation of a high-Mo/Cu magmatic–hydrothermal fluid and the final Mo ± Cu mineralization assemblage. Zircon εHf(t) values of + 4.1 to + 7.9 are indicative of magma derivation from a depleted source. These isotopic data, coupled with other geochemical characteristics of the Narigongma porphyry, such as high SiO2and K2O contents, low MgO contents and compatible element abundances, and highly fractionated rare earth element patterns, indicate a mixing model for the origin of the porphyry bodies. Generation of the post-collisional ore-forming porphyries occurred in two stages: (1) partial melting of metasomatized phlogopite-bearing lithospheric mantle that generated potassic to ultra-potassic mafic melts, and (2) underplating of such melts beneath thickened juvenile lower crust, which triggered partial melting of the lower crust to produce the ore-forming, high-K adakitic magma.
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影响因子：
1.8
作者：
R. Bakker
通讯作者：
R. Bakker
影响因子：
6.1
作者：
Yongjun Lu;R. Kerrich;Peter A. Cawood;T. McCuaig;C. Hart;Zhengyuan Li;Z. Hou;L. Bagas
通讯作者：
Yongjun Lu;R. Kerrich;Peter A. Cawood;T. McCuaig;C. Hart;Zhengyuan Li;Z. Hou;L. Bagas
影响因子：
4.8
作者：
T. Augé
通讯作者：
T. Augé
DOI：
--
发表时间：
1979
期刊：
--
影响因子：
--
作者：
C. Burnham
通讯作者：
C. Burnham
影响因子：
2.6
作者：
Cai Li;A. Zheng
通讯作者：
Cai Li;A. Zheng