(1. 中南大學(xué) 地球科學(xué)與信息物理學(xué)院，長沙 410083；
2. 中南大學(xué) 有色金屬成礦預(yù)測教育部重點(diǎn)實(shí)驗(yàn)室，長沙 410083；
3. 桂林理工大學(xué) 地球科學(xué)學(xué)院，桂林 541004)
摘 要: 對位于厄瓜多爾中新世金屬成礦帶的Beroen金銀礦床不同位置的英云閃長巖和花崗閃長巖進(jìn)行鋯石 U-Pb定年及地球化學(xué)研究。結(jié)果表明：加權(quán)平均年齡分別為(15.92±0.4) Ma和(34.73±0.7) Ma。結(jié)合兩個巖體的地球化學(xué)特征對比，認(rèn)為由于俯沖洋殼板片脫水后，交代軟流圈地幔楔形成相似的母源巖漿在后期演化過程中差異化，漸新世的花崗閃長巖母源巖漿在區(qū)域伸展應(yīng)力背景下上侵，傾向發(fā)育斜長石的結(jié)晶分異。而英云閃長巖是深層熔漿在上侵過程中受到擠壓應(yīng)力作用影響造成停滯形成的，熔體在中下地殼層進(jìn)行以角閃石(±榍石)為主的結(jié)晶分異作用。構(gòu)造背景的改變與Beroen絹云母蝕變形成時間都在中新世，成礦作用與中新世巖漿侵位有密切關(guān)系。
關(guān)鍵字: 厄瓜多爾；Beroen礦床；鋯石U-Pb年齡；埃達(dá)克型；成巖；成礦
（1. School of Geosciences and Info-Physics, Central South University, Changsha 410083, China;
2. Key Laboratory of Metallogenic Prediction of Nonferrous Metals, Ministry of Education, Central South University, Changsha 410083, China;
3. College of Earth Science, Guilin University of Technology, Guilin 541004, China）
Abstract:Beroen gold deposit is part of central Andean miocene metallogenic belt. Zircon U-Pb dating of intrusions of Beroen: tonalite, granodiorite, indicates that tonalite has emplaced in middle Miocene, granodiorite had emplaced in early Oligocene, with weighted average age of (15.92±0.4) Ma and (34.73±0.7) Ma, respectively. Combined with their geochemical characteristics, both intrusions melt derived similarly from slab dehydration fluids fluxing mantle wedge partial melting, then experienced different evolution process. The Oligocene granodiorites were emplaced in a crustal domain extension and emplaced through trench-parallel and trench-normal faults and sutures, through a continuous passive ascent process, with undergoing more plagioclase differentiation. The Miocene tonalite emplaced under compressive stress background with trench parallel structures was sealed. The magmas were thus impeded to rise, ponded and undergone mainly amphibole differentiation at lower crust. The sericite in orebody formed prior to emplacement of tonalite. Maybe Beroen mineralization was resulted from the geodynamic transition of extension condition to compression condition induced by subduction zone’s geodynamic changing.
Key words: Ecuador; Beroen deposit; zircon U-Pb; adakite; petrogenesis; metallogeny
