地质历史中板块构造启动时间

发布时间：2019-02-21 07:56

【摘要】：地质历史中板块构造是何时开始启动的长期存在着激烈的争论,最极端的一是认为板块构造在新元古代的800 Ma前开始,二是在冥古宙4.3 Ga就已启动,多数学者认为在太古宙末开始启动。确定板块构造启动时间主要依据以下几方面:(1)地球动力学特点,如地幔的热状态以及粘塑性地幔对流模拟表明,板块构造可能是在地球热和冷停滞状态之间演化的一个相。在太古宙较热的地球中,板片强度低,板片的频繁断离阻止了形成类似现代样式的长期俯冲体系,太古宙的板块构造是短期的、阵发性的;(2)代表俯冲的标志的蛇绿岩、蓝片岩和超高压(UHP)变质地体;(3)具有弧特征的岩石组合,如拉斑玄武岩-安山岩-英安岩-流纹岩及英云闪长岩-奥长花岗岩-花岗闪长岩(TTG)岩套;(4)增生楔中混杂岩和大洋板块地层、前陆盆地、大陆裂谷、双变质带、造山带;(5)与俯冲带关系密切的造山型Au矿、斑岩Cu矿和浅成热液矿床、火山岩型块状硫化物矿床(VHMS),它们最早出现的年龄一致在3.5~3.1 Ga,指示了板块构造的开始;(6)世界不同地区大陆的Ni/Co、Cr/Zn比值随沉积年龄变年轻而降低,陆壳从3.0 Ga前的镁铁质转变为2.5 Ga时的长英质,表明全球板块构造的启动应在3.0 Ga的古中太古代;(7)冥古宙锆石、太古宙金刚石中矿物包裹体及Hf、O、C、N同位素组成研究表明,冥古宙地球表面存在类似板块汇聚边缘,太古宙含有大陆沉积物的海洋岩石圈俯冲进入地幔。
[Abstract]:In geological history, there has been a heated debate over when plate tectonics began to start. The most extreme is that plate tectonics began before the Neoproterozoic 800 Ma, and the second one was started at 4.3 Ga in the Neoproterozoic. Most scholars believe that it started at the end of Archean. The determination of plate tectonic initiation time is mainly based on the following aspects: (1) geodynamic characteristics, such as the thermal state of the mantle and the simulation of the viscoplastic mantle convection, show that, Plate tectonics may be a phase of evolution between the Earth's hot and cold stagnation states. In the warm Archean earth, the plate strength is low, and the frequent breakup of the plate prevents the formation of a long-term subduction system similar to the modern style. The Archean plate tectonics are short-term and paroxysmal. (2) ophiolite, blueschist and ultrahigh pressure (UHP) metamorphic terrane, which represent the sign of subduction; (3) rock assemblages with arc characteristics, such as tholeiite, andesite, dacite, rhyolite and (TTG) suite; (4) Mesozoic melange and oceanic plate stratigraphy, Foreland basin, continental rift, double metamorphic belt and orogenic belt; (5) Orogenic Au deposits, porphyry Cu deposits and epithermal deposits, and volcanic massive sulphide deposits, which are closely related to subduction zones, their earliest age of occurrence is 3.50.3.1 Ga, indicating the beginning of plate tectonics; (6) the ratio of Ni/Co,Cr/Zn in different regions of the world decreases with the age of deposition, and the continental crust changes from 3. 0 Ga of magnesium-iron to 2. 5 Ga of feldspar. It is suggested that the global plate tectonics should be initiated in the Palaeo-Middle Archean of 3. 0 Ga. (7) the study of the mineral inclusions and Hf,O,C,N isotopic compositions in the Paleozoic zircon, the Archean diamond, shows that there are similar plate convergence margins on the surface of the Earth. The Archean marine lithosphere containing continental sediments subducted into the mantle.
【作者单位】：中国科学院广州地球化学研究所;
【基金】：国家自然科学基金-新疆联合重点基金(U1203291/U1603244) 国家自然科学基金(41273056)联合资助
【分类号】：P542

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