华南云开-南岭地区前泥盆纪构造演化研究

Under the theoretical guidance of modern plate tectonics and continental dynamics, using advanced techniques and analysis means, this program will mainly focus on the Neoproterozoic plate mechanism and the geodynamic settings of tectonic-magmatic-metamorphic event in the early Paleozoic in the Yunkai-Nanling region of the Cathaysia Block, and carry out a systematic study on the following four geological problems:(1) the movement mechanism of Neoproterozoic plate tectonics in Cathaysia,(2) the discrimination for the early Paleozoic oceanic subduction and marmatic arc,(3) the tectonic nature of the early Paleozoic orogen of South China and (4) the tectonic and magmatic rewoking on the pre-Devonian South China framework during the late Paleozoic and the late Mesozoic periods. By systematic researches,the structures of the Cathaysia basement and its Neoproterozoic plate mechanism will be clarified; the suture mechanism, kinematics and suture timing between Yangtze and Cathaysia blocks are hopeful to be illustrated, the deposition environment from Sinian to late Ordovician could be settled well, the petrotectonic assemblages and deformation structures formed by the early Paleozoic tectonic event and the genetic mechanism will be interpreted reasonably and the tectonic nature and geodynamic setting of the early Paleozoic South China Orogenic Belt will be ascertained. By throwing away the superposed affection of after-Devonian tectonic events, this program will reconstruct a pre-Devonian tectonic framework, and proposes a new model of continental dynamic evolution of South China.

以华南云开-南岭地区为研究对象，围绕新元古代板块机制和早古生代变质变形构造背景及其地球动力学演化问题，运用当代板块构造与大陆动力学理论和先进的测试方法技术，选择露头完好的岑溪-信宜、云浮-罗定、鹰扬关-梧州、龙川-兴宁4个区带为重点解剖区，开展(1)华夏块体新元古代板块运动机制,(2)早古生代洋壳俯冲和岩浆弧的甄别,(3)早古生代造山带的构造属性,(4)后期构造-岩浆的再造等内容的研究。通过研究，查明华夏块体的基底组成与新元古代洋陆格局，阐述华夏与扬子两个块体的拼合机制、动向和拼合时间，弄清震旦纪-奥陶纪的沉积与构造环境，诠释早古生代晚期变质变形的特征岩石构造组合及其成因机制，确定早古生代造山带的构造属性及其地球动力学背景，了解泥盆纪后板内的构造-岩浆再造特征及其对前泥盆纪构造的影响，恢复前泥盆纪地球动力学演化过程，为重建华南前泥盆纪构造演化模型提供科学依据。

华南前泥盆纪构造演化研究薄弱，争论较大。本项目选择南岭-云开地区岑溪-信宜、云浮-罗定、鹰扬关-梧州、龙川-兴宁4个区带为重点解剖区，围绕新元古代板块机制和早古生代变质变形构造背景及其地球动力学演化核心问题，运用当代板块构造与大陆动力学理论和先进的测试方法技术，开展研究区(1)华夏块体新元古代板块运动机制,(2)早古生代洋壳俯冲和岩浆弧的甄别,(3)早古生代造山带的构造属性,(4)重建华南板块构造-大陆动力学演化模式（含造山带形成后的陆内构造-岩浆再造）等内容的研究。通过研究，取得5项重要成果。① 查明华夏块体新元古代是一个多地体构造格局，存在少量9-10亿年古岛弧岩浆岩。② 确定云开-南岭地区震旦纪-奥陶纪均为板内浅海相沉积环境，不存在早古生代洋壳俯冲和岛弧物质证据。③ 研究区在晚奥陶世-早泥盆世期间受东南亚板块俯冲-碰撞影响，发生强烈构造变形、区域低绿片岩相变质和花岗岩浆作用，峰期年龄440-420 Ma，形成华夏陆内造山带。确定云开-南岭地区早古生代晚期构造变形的运动学特征，为一个顶朝N-NW方向的逆冲构造，对应江南朝华夏块体的陆内俯冲，伴有左旋走滑剪切变形。④ 发现可靠证据，确定了早-中三叠世板内的构造-岩浆再造特征及其对前泥盆纪构造的影响。 重建了云开-南岭地区前泥盆纪地球动力学演化过程，构建了华南前泥盆纪构造演化模式。本基金项目开展了两次中法联合野外考察，培养出了3位博士。研究成果在国内外期刊上发表，计国际SCI期刊10篇，国内核心4篇。