古华夏块体群的类型及特征

以"中国海陆及邻域大地构造格架图"的编制为契机,块体构造学说被提出。该学说将中国海陆及邻域的地壳演化史分为5个阶段:陆核形成阶段、古全球构造阶段(包括成台过渡和稳化阶段)、中间阶段和新全球构造阶段,在用板块构造理论解释新全球构造阶段构造演化的基础上,将块体和结合带赋予新的定义和内涵,作为板块之下的二级构造单元,用以表示古全球构造阶段的大地构造单元。二叠纪末期,聚合的Pangea大陆在中国及邻域存在3个块体群:劳亚块体群、古华夏块体群以及冈瓦纳块体群。古华夏块体群由众多规模不大,但地壳发育历史复杂的块体组成,蕴含丰富的大地构造信息。通过收集、整理区域构造背景和岩性地层等资料,并对各种体现大地构造演化阶段的测年数据进行详细分析,将古华夏块体群划分为华北、扬子、华南3种类型,对其演化阶段进行了详细的厘定。华北型块体于古元古代末期(约1.8 Ga)完成成台过渡;扬子型块体于新元古代初(约800 Ma)完成成台过渡;华南型块体于早古生代末期(约400 Ma)完成成台过渡,之后各类块体分别进入稳化阶段,直至早二叠世末一起进入中间阶段,体现了地壳演化中的同序时差现象。印支运动后,又作为欧亚板块的一部分,随板块一起参与到新全球构造阶段的演化旋回中。

TYPES AND CHARACTERISTICS OF THE CATHAYSIAN BLOCK GROUP

The theory of block tectonics was put forward when the mapping project on "Tectonic Frame Map of China and Adjacent Regions" was lunched. With it the crustal evolution of China and adjacent regions is divides into 5 stages:the continental nucleus forming stage, the paleo-global tectonic stage which includes the platform forming stage and the stabilizing stage, the transitional stage and the neo-global tectonic stage. Blocks and junction belts are adopted and redefined as the second order tectonic units under the plate to reveal the tectonic evolution of the paleo-global tectonics stage, as the theory of plate tectonics has successfully illuminated the global tectonic evolution in the neo-global tectonic stage. By Late Permian, there were 3 block groups in China and adjacent regions as part of the Pangea:the Laurasia Block Group, the Cathaysian Block Group and the Gondwana Block Group. The Cathaysian Block Group is composed of a number of smaller blocks which have complicated evolutionary history and rich tectonic information respectively. In this paper, we collected and studied the data of regional tectonics, lithology and stratigraphy, plus detailed analysis of isotope dating data related to tectonic evolution stages, divided the Cathaysian Block Group into three types of North China, Yangtze and South China and stipulated their evolutionary history in detail. The platform forming stage of the North China type was completed in late PaleoProterozoic about 1.8Ga, the platform forming stage of the Yangtze type in early NeoProterozoic about 800 Ma, and the platform forming stage of the South China type by the end of Early Paleozoic 400Ma. Once the platforms were formed, they entered the stabilizing stage until the end of early Permian when they entered the transitional stage. Their evolution shows a similar sequence but different time schedule. After the Indosinian movement, as parts of the Eurasian Plate, the Cathaysian Blocks have moved into the neo-global tectonic stage.