波罗的与西伯利亚板块古生代运动学特征对比新认识  

New Understanding From Comparison of Paleozoic Kinematics Between Baltica and Siberia

作　　者：傅臣建[1] 李江海[1] 

机构地区：[1]北京大学地球与空间科学学院,造山带与地壳演化教育部重点实验室,北京100871

出　　处：《高校地质学报》2012年第2期280-290,共11页Geological Journal of China Universities

基　　金：国家科技部973项目(2009CB219302)资助

摘　　要：古地磁学是进行古板块运动演化过程和古地理重建研究最有效的定量方法之一。在统计全球古地磁数据库(GPMDB)和前人发表数据的基础上,根据国际上通用的古地磁数据可靠性判别标准——VanderVoo(1990)判据,本文对波罗的板块(Baltica)和西伯利亚板块(Siberia)古生代古地磁数据进行了重新分析和筛选,利用GMAP软件重建了两个板块古生代视极移曲线和古地理方位,对它们的构造演化和运动学特征进行对比分析,获得了几点新认识,即两板块在古生代期间发生的三次汇聚(晚奥陶世、早石炭世和晚二叠世)过程符合牛顿运动学原则(板块之下是具有很大粘度的地幔软流圈,非理想条件下不可能完全遵守牛顿运动学原则),且具有三种不同类型的运动学现象:晚奥陶世(～450Ma),波罗的和西伯利亚板块同向北漂移并汇聚,纬向速度较快的板块波罗的将动能传给了纬向速度较慢的西伯利亚板块;早石炭世(～360Ma),波罗的和西伯利亚板块相向漂移并汇聚,西伯利亚板块向南的板块纬向速度转为向北,波罗的板块向北的纬向速度逐渐减小并转为向南;晚二叠世(～255Ma),波罗的和西伯利亚板块再次相向漂移并汇聚,动能抵消,纬向漂移速率都变为零。Paleomagnetism is one of the most effective quantitative methods for examining ancient plate tectonic evolution and paleogeographic reconstructions. Based on data from the Global Paleomagnetic Database （GPMDB 4.6） and previously published paleomagnetic data for the Baltic and Siberian plates, a reanalysis and filtering of Baltica and Siberia Paleozoic paleomagnetic data has been performed in accordance with internationally accepted basic selection criteria （Van der Voo, 1990） determining the reliability of paleomagnetic data. From this, a reconstruction of the apparent polar wander paths （APWP） and paleogeographic positions of the Baltic and Siberian plates has been made by using the GMAP software. In addition, further analysis has been made by comparing the structural evolution and kinematic characteristics. In conclusion, the following is understood for these two plates during the Paleozoic. Three convergence events took place during the Late Ordovician （-450 Ma）, Early Carboniferous （-360 Ma）, and Late Permian （-255 Ma）, and the processes of plate convergence follow Newtonian kinematic principles in general. What needs to be stressed is that under the continental plates is the asthenosphere mantle with an extremely high viscosity, so the Newtonian kinematic principles cannot be obeyed under non-ideal conditions. Three processes of plate convergence have three different kinematic phenomena. During the late Ordovician （-450 Ma）, both Baltiea and Siberia drifted northward and converged gradually. Baltica with higher latitudinal velocity converted its kinetic energy into Siberia with lower latitudinal velocity. During the Early Carboniferous （-360 Ma）, Ballica and Siberia moved towards each other and converged. The latitudinal drift direclion of Siberia changed ft-om the south In the norih while the latihulinal velocity of Bahica decreased and became toward lhe south gradually. During the Late Permian （-255 Ma）, Bahica and Siberia drifted towards each other and converged again.

关 键 词：波罗的和西伯利亚板块 古地磁 运动学原则 视极移曲线 纬向漂移速率 旋转速率 

分 类 号：P318[天文地球—固体地球物理学] P541[天文地球—地球物理学]