摘要
桂西南广泛发育一套与微粒型金矿密切相关的早三叠世中酸性火山岩。主要见于下三叠统北泗组第四段，具潮坪特点，层序上处于下伏的 HST和上覆的 TST之间。岩石类型为流纹岩、英安岩和沉火山碎屑岩，其中的熔结角砾凝灰岩是本次 1∶ 5万区调中的新发现。三种火山岩均属钾质钙碱性系列，岩石化学成分显示为同源岩浆产物。运用多种岩石地球化学数据判别：其产出的大地构造环境为活动陆缘。岩浆来源深度较大，与太平洋库拉板块向亚洲板块俯冲，高能热流导致上地幔部分熔融上涌，穿透巨厚壳层时吸收了部分壳源重熔物质有关，其上涌通道主要沿被激活的凭祥─东门深断裂。
There exists an extended set of early Triassic intermediate－acid volcanics closely related to microdot gold ore in Southwestern Guangxi.It is mainly distributed in the fourth part of the Beisi Formation of the lower Triassic,exhibiting tidal flat characteristics and located between the underlying HST and the upper TST.The rock types include rhyolite,dacite and sedimentary volcaniclastic rocks,among which the lava tuff breccia was newly discovered in the 1∶ 50 000 region.The three volcanics are of kalium alkaline series,with their chemical elements showing the same magma origin.The multi－geochemical data analysis shows that the occurring tectonic environment is an active continental margin.Caused by the underthrust of the Pacific Kula Plate towards the Asia Plate,the high energy thermal flow brought the magma in the great depth of the upper mantle to force its way through the huge thick crust rock layers and absorbed the melted materials.The ascending channel should be along the activated Pingxiang－Dongmen deep fault.
出处
《大地构造与成矿学》
EI
CAS
CSCD
北大核心
2001年第2期141-148,共8页
Geotectonica et Metallogenia
基金
广西自然科学基金资助项目(编号: 9717001)
关键词
中酸性火山岩
早三叠世
岩石地球化学
构造环境
广西
Intermediate－acid volcanics
early Triassic
rock geochemistry
tectonic environment
southwestern Guangxi
