西秦岭天水地区“李子园群”的解体及其构造环境浅析

Analysis of the disintegration and tectonic setting of the "Liziyuan Group" in the Tianshui area, western Qinling

依据岩石组成及变质变形特征,西秦岭天水地区“李子园群”可解体为5部分。初步研究认为,关子镇蛇绿岩形成于洋盆环境;流水沟变质中基性杂岩体为加里东期岛弧型深成杂岩体;李子园群(狭义)形成于北秦岭南缘弧前盆地环境;太阳寺岩组形成于扬子板块北缘被动陆缘环境;舒家坝群上部灰岩组形成于西秦岭微板块北缘半深海—深海盆地环境。

The 'Liziyuan Group' in the Tianshui area, western Qinling, can be disintegrated into five parts according to its composition and metamorphic and deformation features. By field survey and study, the authors have the following ideas: the Guanzizhen ophiolite formed in an ocean basin environment; the Liushuigou meta-intermediate-basic complex is a Caledonian island-arc-type plutonic complex; the Liziyuan Group (in a narrow sense) formed in an forearc basin at the south margin of the North Qinling; the Taiyangsi Formation formed in passive continental-margins at the northern margin of the Yangtze plate; and the Limestone Formation of the Upper Shujiaba Group formed in a bathyal to abyssal basin at the north margin of the West Qinling microplate in the Devonian.