陕西勉略宁元古宙海相火山岩成岩构造环境及演化

勉略宁元古宙海相火山岩，划分为四个火山岩带，通过对火山岩带地球化学的研究，旨在揭示火山岩带的成岩环境，追踪火山作用的演化历史。研究认为勉略宁元古宙海相火山岩发生发展于裂陷海盆中，经历了扩张－裂陷、叠缩－消减和碰撞－造山三个演化阶段。南带和中带火山岩分别形成于扩张－裂陷的早期和晚期，其中罗家山火山岩产于洋岛环境；北带火山岩为叠缩－消减的岛弧环境；在碰撞－造山过程中产于不同环境的火山岩带叠缩、构造拼贴作为添加地体拼合在扬子板块西北缘

THE DIAGENETIC STRUCTURAL ENVIRONMENT AND STRUCTURAL EVOLUTION OF PROTEROZOIC MARINE VOLCANIC ROCKS IN THE MIAXIAN-LUEYANG-NINGQIANG AREA, SHAANXI

The Proterozoic marine volcanic rocks in the Mianxian-Lueyang-Niqiang area are divided into four volcanic belts. Study on geochemistry of the volcanic belts is aimed at clarifying diagenetic environment and tracing historical evolution of volcanism. It is revealed that the Proterozoic marine volcanic rocks in this area were derived from and developed in the rifting oceanic basin, and went though spreading-rifting and shrinking-subduction and collision-orogeny. The volcanc rocks in the central and southern belts were formed in early spreading period and late rifting period respectively, in which the volcanic rocks in the Luojiashan area were formed in ocean island .The volcanic rocks in the north belt were formed in shrinking and subduction environment. In the collision and orogenic process, the volcanic belts derived from different environments were shrinked and added onto and matched with Yangtz platform on the northwest margin as an annexd terrain.