新疆西天山北缘浅成低温热液金成矿作用OA

The northern margin of the West Tianshan in Xinjiang is well endowed with epithermal gold de-posits.These deposits are primarily hosted in the continental volcanic rocks of the Late Devonian-Early Car-boniferous Dahalajunshan Formation and are concentrated in the Tulasu and Yelimodun volcanic fault-depres-sion basins and the Wusunshan area.Based on a systematic review of the geological and geochemical character-istics of typical gold deposits such as Axi,Jingxi-Yermand,and Tawuerbieke in the region,this paper analyzes the relationship between gold mineralization and regional tectonic-magmatic evolution,and discusses the post-mineralization modification and preservation processes as well as their implications for mineral exploration.The epithermal gold deposits in the northern margin of the West Tianshan include various types such as low-sulfida-tion,high-sulfidation,and porphyry-epithermal transitional types,which exhibit significant differences in ore body occurrence,ore texture,mineral assemblages,and alteration characteristics.The ore-forming materials are mainly derived from the host volcanic-subvolcanic rocks,and the ore-forming fluids consist primarily of mag-matic hydrothermal fluids(high-sulfidation type),meteoric water(low-sulfidation type),or a mixture of these two fluids(porphyry-epithermal transitional type).Gold precipitation mechanisms include fluid boiling,water-rock interaction,and fluid mixing.The mineralization age is mainly concentrated in the Late Devonian-Early Carboniferous,formed in a back-arc extensional environment during the peak subduction of the North Tianshan and South Tianshan oceans.After their formation,the deposits underwent a complex modification and preserva-tion history.The epithermal gold deposits in the Tulasu and Yelimodun basins have been preserved due to rela-tively weak erosion,and their deep sections hold potential for the discovery of porphyry-skarn-type Cu-Au poly-metallic deposits.In contrast,the peripheral areas of the basins have experienced higher degrees of erosion,lead-ing to the destruction of most epithermal deposits,but the prospects for porphyry-and skarn-type deposits re-main favorable.