CAJ | 학술논문

位于冈底斯构造成矿带中段西侧的朱诺地区具有良好的成矿前景,已发现有朱诺大型斑岩铜矿床和铁雅铁铜矿点.野外基础地质和矿床地质调查、构造分析和岩石化学的研究表明,朱诺斑岩铜矿床在构造上受近EW向和近SN向伸展断裂控制,时间上属于中新世青藏高原南部板内构造过程,含矿斑岩具有典型的埃达克质岩特征.朱诺及其所在的冈底斯构造成矿带在中新世处于板内构造环境,板内伸展构造-埃达克质岩-斑岩铜矿系统叠加在早期的俯冲-碰撞构造岩石组合之上.与埃达克质岩形成直接相关的下地壳流动导致冈底斯上地壳及下地壳显著加厚,发生部分熔融作用,下地壳物质可能源于地壳减薄的锡瓦利克盆地,流经喜马拉雅,穿过并改造了雅鲁藏布江缝合带中挤入地壳的洋壳地幔岩石,造成被混入洋壳地幔成分的冈底斯下地壳发生部分熔融,形成埃达克质岩浆,上升并顶托冈底斯上地壳,致使冈底斯上地壳先后发生近EW向和近SN向的伸展,在上地壳伸展扩容空间中含矿埃达克质岩浆沿伸展断裂上升、侵位,并富集成矿.
위우강저사구조성광대중단서측적주낙지구구유량호적성광전경,이발현유주낙대형반암동광상화철아철동광점.야외기출지질화광상지질조사、구조분석화암석화학적연구표명,주낙반암동광상재구조상수근EW향화근SN향신전단렬공제,시간상속우중신세청장고원남부판내구조과정,함광반암구유전형적애체극질암특정.주낙급기소재적강저사구조성광대재중신세처우판내구조배경,판내신전구조-애체극질암-반암동광계통첩가재조기적부충-팽당구조암석조합지상.여애체극질암형성직접상관적하지각류동도치강저사상지각급하지각현저가후,발생부분용융작용,하지각물질가능원우지각감박적석와리극분지,류경희마랍아,천과병개조료아로장포강봉합대중제입지각적양각지만암석,조성피혼입양각지만성분적강저사하지각발생부분용융,형성애체극질암장,상승병정탁강저사상지각,치사강저사상지각선후발생근EW향화근SN향적신전,재상지각신전확용공간중함광애체극질암장연신전단렬상승、침위,병부집성광.
Zhunuo area located in western Gangdese metallogenic belt reveals good metallogenic prospects, where Zhunuo large-scale porphyry copper deposit and the Tieya iron-copper polymetallic ore spot have been discovered recently. Based on the field deposit-geological investigations, structural analysis and petrochemistry studies, this paper presents a Miocene intraplate thermo-upwelling extensional metallogenic model of the Zhunuo porphyry copper deposit which is tectonically controlled by the nearly east-west and north-south extensive faults related to lower crustal flow. The ore-bearing porphyries have the characteristics of typical adakitic rock. The Zhunuo area and Gangdese belt belonged to intraplate tectonic setting in Miocene, where the earlier subduction-collision tectonics was superimposed by the intraplate extensional tectonics, adakitic rocks, and porphyry copper system. The lower crustal flow and partial melting produced adakitic rocks and lead to Gangdese crustal thickening. The flowing material of lower crust may originate from the Himalayan foreland basin with crust thinning, flowing through Himalayas and the Brahmaputra Suture Zone, and reforming the mantle rocks of Neo-Tethys oceanic crust. Therefore,the Gangdese lower crust mixed Neo-Tethys mantle materials and generated adakitic magma by partial melting. The lower crustal flow leads to nearly east-west trend and north-south trend extension successively in the Gangdese upper crust, the ore-bearing adakitic magma rose and emplaced the normal faults from lower crust, and controlled ore formation processes.