龐家河金礦韌性剪切帶特征研究

李鵬貝

摘 要：秦嶺鳳縣龐家河金礦位于華北板塊與揚子板塊之間的商丹加里東結合帶中的次級混雜巖帶，即唐藏-商丹構造混雜帶。龐家河金礦主要出露地層為泥盆系舒家壩組和大草灘組，主要含礦巖層為舒家壩組的絹云千枚巖、粉砂質千枚巖。本文通過對礦區內多種控礦構造樣式宏微觀特征等進行調查發現，區內地層巖石構造均明顯發育脆-韌性剪切變形變質特征，表明研究區巖層經歷過強烈的韌性剪切作用。研究認為，脆-韌性剪切帶是龐家河金礦的重要控礦構造。從地層巖石變形變質、礦體形態、礦石類型等來看，均體現出韌性剪切帶型金礦特征。在“賦金地層—脆-韌性剪切帶—熱液活動”共同作用下形成龐家河大型中低溫微細粒浸染型金礦。

關鍵詞：脆-韌性剪切帶;控礦構造;龐家河金礦

中圖分類號：P618.510.1 文獻標識碼：A 文章編號：1003-5168（2019）34-0095-03

Study on the Characteristics of Ductile Shear Zone

in the Pangjiahe Gold Deposit

LI Pengbei

（School of Geosciences and Resources， Changan University，Xi’an Shaanxi 710054）

Abstract： The secondary hybrid rock band in the combined belt between the North China plate and the Yangtze plate in the Pengjiahe gold deposit in Fengxian， Qinling—Tangzang-Shangdan construction hybrid belt，The main exposed strata of Pangjiahe gold deposit are Devonian Shujiaba formation and Dacaotan formation. In this paper， through the investigation of the macro and micro characteristics of various ore-controlling structural styles in the area， it was found that the formation rock structures in the area are obviously characterized by brittle-ductile shear deformation and metamorphism， which indicated that the strata in the study area had experienced strong ductile shear. It is considered that the brittle-ductile shear zone is an important ore-controlling structure of Pangjiahe gold deposit. According to the deformation and metamorphism of strata and rocks， the shape of orebody and the type of ore， all of them show the characteristics of ductile shear zone type gold deposits. Large medium-low-temperature micro-fine disseminated gold deposits in the Pangjiahe River were formed under the action of "gold-bearing strata-brittle-ductile shear zone-hydrothermal activity ".

Keywords： brittle - ductile shear band;ore-controlling structure;Pangjiahe gold deposit

龐家河金礦位于陜西鳳縣北部，處于華北板塊和揚子板塊之間的唐藏-商丹構造混雜巖帶內[1]。區內地層經歷了多期變形變質作用，反映了構造和蝕變對金礦成礦有利的控制作用，控礦構造為走向近EW的脆-韌性剪切帶[2-4]。通過對區內地層及構造進行觀察發現，龐家河金礦賦礦層位淺灰～淺褐色蝕變千枚巖帶是一套分枝、復合和波狀彎曲的層間擠壓剪切破碎帶。因此，擬根據剪切帶內巖石變形變質特征，從觀察賦礦地層的構造現象入手，結合光學顯微鏡下光薄片微觀研究，分析該區成礦運動學和動力學背景、控礦構造特征，從而為龐家河金礦深部找礦提供構造學方面的依據。……