古亚洲洋与古特提斯洋关系初探

从板块构造研究中国古生代洋陆关系和构造-岩浆-成矿作用,离不开对古亚洲洋和古特提斯洋的关系判断,特别是对于中国西北部的研究,两个古生代大洋形成演化和关系是理清重要地质构造和成矿事件的关键。本文认为早古生代的原特提斯洋与古亚洲洋应连为一体,合称古亚洲-原特提斯洋,简称古亚洲洋。古亚洲洋是发育于早古生代劳亚大陆与冈瓦纳大陆之间的大洋,金川超大型铜镍矿床的形成是元古宙罗迪尼亚超大陆裂解三叉裂谷开启大洋的开始,塔里木陆块作为古亚洲洋南岸的一个陆块,早古生代的昆仑洋、祁连洋和秦岭洋只是古亚洲洋的分支或次生洋盆,这些次生洋盆于志留纪末闭合,古亚洲洋主洋则直到晚古生代泥盆纪末才闭合。石炭纪天山及邻区是古亚洲洋闭合后板块构造后碰撞机制与地幔柱作用提供热动力的两种地球动力学机制并存的构造背景,为大规模壳幔混合(染)岩浆作用和成矿爆发提供了可能。古特提斯洋是古亚洲洋在晚古生代的发展和继承,东昆仑夏日哈木超大型铜镍矿床的产生是冈瓦纳大陆北侧志留纪末破裂三叉裂谷开启大洋的开始,塔里木和华北等泛华夏陆块群构成了古特提斯洋北岸陆缘,石炭纪大洋形成,西昆仑玛尔坎苏大型优质锰矿可能就形成于大洋北侧被动大陆边缘的浅海或陆表海,成矿物质则很可能来自于同时代的大洋中脊。德尔尼大型铜钴矿为晚石炭世大洋中脊塞浦路斯型块状硫化物矿床。而铜峪沟大型铜矿和大场大型金矿等则分别为古特提斯洋消减俯冲岛弧岩浆作用矽卡岩-斑岩矿床和浅成低温热液矿床。中三叠世末古特提斯洋闭合。

The primary discussion on the relationship between Paleo-Asian Ocean and Paleo-Tethys Ocean

To study the relationship between Chinese Paleozoic ocean-continent and tectonic-magmatic-metallogenesis through plate tectonics, it is essential to determine the relationship between Paleo-Asian Ocean and Paleo-Tethys Ocean. Especially, for the research of Northwest China, the formation and evolution for the two Paleozoic oceans is the key to understand the geological structure and mineralization events. In this paper, it is believed that Early Paleozoic Proto-Tethys Ocean and Paleo-Asian Ocean is one ocean, and it can be called the Paleoasian-Prototethys Ocean or the Paleo-Asian Ocean for short. The Paleo-Asian Ocean is an Early Paleozoic ocean developed between Laurasia and Gondwana, and the forming of Jinchuan giant magmatic Ni-Cu sulfide deposit means the opening of the ocean owing to cracking of triennial rift in the Proterozoic Rodinia supercontinent. The Tarim block is located in the south of the Paleo-Asian Ocean, and the Early Paleozoic Kunlun ocean, Qilian ocean and Qinling ocean are branches or secondary ocean basins of the Paleo-Asian Ocean. These secondary ocean basins closed in Late Silurian era, but the main ocean of the Palaeo-Asian Ocean was closed until the Devonian era. In the Carboniferous era, there are two coexisting geodynamic tectonic settings in the Tianshan and its adjacent areas, which are the post-collision mechanism of plate tectonic after closure of the Paleo-Asian Ocean and the heating mechanism of plume, and this kind of setting provides the possibility for large scale magmatic mixing or contamination between crust and mantle, and large metallogenic explosion. The Paleo-Tethys Ocean is the development and inheritance of the Paleo-Asian Ocean in Late Paleozoic era, and the forming of Xiarihamu ultra-large magmatic Ni-Cu sulfide deposit in East Kunlun means the opening of ocean owing to cracking of triennial rift in the northern part of Gondwana continent in Late Silurian era. The Pan Cathaysian landmass group including the Tarim block and North China block contribute the north continental margin of the Paleo-Tethys Ocean, and the Paleo-Tethys Ocean is formed in Carboniferous era. The Maerkansu high quality manganese deposit in West Kunlun was formed in neritic or surface sea of the north passive continental margin of the ocean, and the ore-forming materials probably originated from the mid ocean ridge. The Deerni large copper-cobalt deposit is a Cyprus-type massive sulfide deposit was formed in the Late Carboniferous oceanic ridge of the Paleo-Tethys Ocean. The Tongyugou large skarn-porphyry copper deposit and the Dachang large epithermal gold deposit are the products of the arc magmatism resulting with the subduction of the Paleo-Tethys Ocean. The Paleo-Tethys Ocean closed in Late Triassic era.