摘要
浅成低温热液系统可能是深部斑岩成矿系统的表征。在澜沧裂谷,喜山期花岗斑岩隐伏侵入裂谷中部下石炭统依柳组玄武质火山岩地层,形成了与老厂大型钼铜银铅锌多金属矿床有关的斑岩-夕卡岩型热液蚀变体系,在浅表的碳酸盐岩地层中则形成脉状银铅锌矿化。裂谷西部的大黑山勘查区下石炭统地层为南段组碎屑岩,深部隐伏的花岗斑岩可能形成不同于老厂的热液蚀变体系,对大黑山勘查区一个综合垂直剖面的初步研究表明:(1)深部热液体系在南段组中以形成具有明显Eu正异常(δEu=1.58)的石英网脉为特征,并且具有与老厂蚀变斑岩相似的Pb-Bi-Ag-Zn-Cu富集模式但Mo明显亏损,暗示深部可能存在与老厂矿区相同的花岗斑岩及Mo的矿化。(2)深部热液体系在C_(1n)/C_(2+3)岩性界面与低温天水系统混合,在C_(2+3)白云岩中形成具有突出Eu正异常(δEu最高达5.71)的铁锰方解石化,并在近40 m的蚀变带内显示出Pb-Zn-Ag矿化异常;蚀变过程中Mg的带出与Ca-Fe-Mn的带入具有良好的相关性,并形成继续向上运移的低温Mg-Mn热液。(3)低温Mg-Mn热液在上覆二叠系生物碎屑灰岩中形成热液角砾白云岩化蚀变,大黑山勘查区地表以线型正地形的黑山梁子为代表;热液角砾白云岩化表现为弱的Eu正异常、Sr-U明显亏损和强烈的Mn富集,是地表锰银矿化的重要物源。大黑山综合剖面的研究确证了地表灰岩中广泛存在的各种形式的热液角砾白云岩化是深部岩浆热液活动的具体体现,是非常有利的找矿标志。
Himalayan granitic porphyry concealed invaded into the basaltic volcanic strata of early Carboniferous Yiliu Formation in middle of Lancang rift, which has been resulted in forming the porphyry-skarn hydrothermal alteration system relative with the large Mo-Cu-Ag-Pb-Zn polymetallic ore deposit of Laocang Area, Yunnan Province, China. A distinguishing hydrothermal alteration system has been predicted for deep concealed granitic porphyry invaded into the calstic rocks of early Carboniferous Nanduan Formation in Daheishan exploration area. Preliminary research on a comprehensive vertical section in Daheishan area indicates that：（1） the deep part of hydrothermal system in Nanduan Formation forms quartz veinlet characterized by distinct positive Eu anomaly（δEu=1.58） and Pb-Bi-Ag-Zn-Cu enrichment model similar to Laocang altered porphyry, revealing that there is Laochang-type granitic porphyry and Mo mineralization in deep of Daheishan exploration area;（2） the deep hydrothermal system mixed with the shallow low-temperature meteoric fluid system in C_（1n）/C_（2＋3） lithological interface, and nearly 40 meters iron-manganese calcitization alteration zone typical with prominent positive Eu abnormal（the highest δEu=5.71） and Pb-Zn-Ag mineralization has been formed. During the processes of alteration, the move out of Mg and the addition of Ca-Fe-Mn have a good relationship, and the new hydrothermal system enriched with Mg-Mn also has been produced; and（3） hydrothermal breccia dolomitization, which is represented by linear positive topography of Heishan ridge in Daheishan area, caused by the Mg-Mn enrichment hydrothermal fluid alterated with the overlying bioclastic limestone of the Permain. The hydrothermal breccia dolomitization is a character with obvious Sr-U depletion and strong Mn-enrichment, and is an important resource for the surface Mn-Ag mineralization. The vary of hydrothermal breccia dolomitization in the surface limestone has been confirmed as a good indicator for deep magmatic h
出处
《矿物学报》
CAS
CSCD
北大核心
2016年第3期343-353,共11页
Acta Mineralogica Sinica
基金
国家自然科学基金项目(批准号:41072054
41530210)
国家973项目(编号:2015CB452603)
关键词
喜山期斑岩热液体系
石英网脉
铁锰方解石化
热液角砾白云岩化
澜沧裂谷
Himalayan porphyry hydrothermal system
quartz veinlet
iron-manganese calcitization
hydrothermal breccia dolomitization
Lancang rift
