当前位置: X-MOL 学术Gondwana Res. › 论文详情
Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)
In-situ mineralogical interpretation of the mantle geophysical signature of the Gangdese Cu-porphyry mineral system
Gondwana Research ( IF 7.2 ) Pub Date : 2022-07-16 , DOI: 10.1016/j.gr.2022.07.005
Bo Xu , Zeng-Qian Hou , William L. Griffin , Suzanne Y. O'Reilly , Yuan-Chuan Zheng , Tao Wang , Bin-Fu , Ji-Feng Xu

The lithosphere provides a reservoir for ore-forming elements introduced by repeated fertilisation during asthenosphere-lithosphere interaction by the slab subduction. Here we use the Gangdese copper metallogenic belt to show how mineralogical study can help to interpret these mantle signatures. We present insights into the in-situ geochronological, geochemical and whole-rock isotopic analyses of minerals from mantle-derived lamprophyres that intruded the Bairong Cu-porphyry deposit in the Gangdese metallogenic belt. Zircon U-Pb dating yields weighted-mean concordant 206Pb/238U ages of 11.69 ± 0.27 Ma to 12.41 ± 0.83 Ma. These zircons show juvenile εHf (t) (+1.0 ∼ +10.9) and low δ18O (5.5‰ ∼ 7.7‰) values. Variable initial 87Sr/86Sr ratios (0.7073–0.7080), εNd(t) values (−6.3 ∼ −5.0) and initial 187Os/188Os ratios (0.1382–0.1591) suggest hybridization between lithosphere mantle and asthenospheric melts. Phlogopites in the lamprophyres reflect partial dissolution and incipient melting with low Mg# values but high Al2O3 contents in core. And these phlogopites are surrounded by a zone with high Mg# values. We interpret this as superheating and hybridization of refractory lithosphere mantle and asthenosphere. The 3-D magnetotelluric and seismic signature of the Gangdese mineral belt reflect a mantle source region comprising asthenosphere, old refractory lithosphere, ponded mafic melts near the crust-mantle boundary, and higher-level magma chambers where more extensive mixing between crust- and mantle-derived melts occurs. The asthenospheric upwelling provides a mechanism for heat transfer and the expulsion of volatile elements. It is generating a new young, fertile lithosphere beneath the southeast Lhasa block, which has driven the mineralization processes in the Gangdese metallogenic belt.



中文翻译:

冈底斯铜斑岩矿物系统地幔地球物理特征的原位矿物学解释

岩石圈为板片俯冲软流圈-岩石圈相互作用过程中反复施肥引入的成矿元素提供了储层。在这里,我们使用冈底斯铜成矿带来展示矿物学研究如何帮助解释这些地幔特征。我们提出了对侵入冈底斯成矿带白绒铜斑岩矿床的幔源灯斑矿物的原位年代学、地球化学和全岩同位素分析的见解。锆石 U-Pb 测年得出的加权平均一致206 Pb/ 238 U 年龄为 11.69 ± 0.27 Ma 至 12.41 ± 0.83 Ma。这些锆石显示幼年 ε Hf (t) (+1.0 ∼ +10.9) 和低 δ 18O (5.5‰ ∼ 7.7‰) 值。可变的初始87 Sr/ 86 Sr 比率(0.7073-0.7080)、ε Nd(t)值(-6.3 ∼ -5.0)和初始187 Os/ 188 Os 比率(0.1382-0.1591)表明岩石圈地幔和软流圈熔体之间存在杂交。灯石中的金云母反映部分溶解和初熔,Mg# 值低但 Al 2 O 3高核心内容。并且这些金云母被高 Mg# 值的区域所包围。我们将此解释为耐火岩石圈地幔和软流圈的过热和混合。冈底斯矿带的 3-D 大地电磁和地震特征反映了一个地幔源区,包括软流圈、古老的难熔岩石圈、壳幔边界附近的池状镁铁质熔体,以及地壳和地幔之间更广泛混合的高层岩浆房衍生熔体发生。软流圈上升流提供了传热和排出挥发性元素的机制。它正在拉萨地块东南部下方形成一个新的年轻肥沃的岩石圈,推动了冈底斯成矿带的成矿过程。

更新日期:2022-07-16
down
wechat
bug