武夷地块中南平-宁化构造带南华纪弧火山岩属性及其对华夏板块多微地体拼合的启示

武夷地块中各地体的活动解析是认识华夏板块构造活动演化的窗口.南平宁化构造带作为划分南武夷地体和北武夷地体的重要边界活动带,其构造属性对我们认识武夷地块中南、北武夷地体的构造演化具有重要意义.前人对南平-宁化构造带中变质火山岩类的研究和认识存在争议,限制了我们对南平-宁化构造带的构造属性的理解.因此,本文利用野外路线地质调查、年代学测定、同位素地球化学测试等手段,对该套变质火山岩做了重点研究,结合前人的研究成果,我们得到以下认识:南平-宁化构造带中的变质火山岩类主要形成于756～720 Ma,主要形成于活动大陆边缘或岛弧环境,表明南平-宁化构造带可能代表了南武夷地体和北武夷地体之间的一条南华纪的近东西向的岛弧火山活动带,结合带中构造变形反映的南北向对冲的汇聚极性,我们认为南武夷地体和北武夷地体之间在南华纪可能还存在洋-陆碰撞乃至陆-陆拼合过程,这也反映了多微地块、多期拼合过程可能更符合华夏板块大地构造演化的主旋律.

The properties of Nanhua arc volcanic rocks in the Nanping- Ninghua tectonic belt of the Wuyi terranes and its implications for the integration of multi- micro- terranes in the Cathaysia block

The tectonic activity analysis of the micro- terranes in the Wuyi block is a window to understand the tectonic evolution of the Cathaysia block. As an important boundary that divides the South Wuyi terrane and the North Wuyi terrane, the Nanping- Ninghua tectonic belt played a crucial role in the tectonic evolution between the South Wuyi terrane and North Wuyi terrane. However, previous research and understanding of the metamorphic volcanic rocks in the Nanping- Ninghua tectonic belt are still controversial, which limits our understanding of the tectonic properties of the Nanping- Ninghua tectonic belt. Therefore, in this paper, we mainly focus on the study of the meta- volcanic rocks by field route geological survey, geochronology dating and isotope geochemistry in the Nanping- Ninghua tectonic belt. Combined with the previous research, we suggest that the metamorphic volcanic rocks in the Nanping- Ninghua tectonic belt were mainly formed at 756~720 Ma in an active continental margin or island arc environment, which would indicate that the Nanping- Ninghua tectonic belt may represent a nearly east- west island arc volcanic belt between the South Wuyi terrane and North Wuyi terrane in the Nanhua period. Combined with the convergence polarity of the south- north offset reflected by the tectonic deformation in the tectonic belt, we proposed that there may still be ocean- land collision or land- land merging between the South Wuyi terrane and the North Wuyi terrane in the Nanhua period, which indicates that the multi- micro- terranes and multi- stage collision may be major characteristics for the tectonic evolution process in the Cathaysia block.