新生代東亞主要地塊運動及板塊邊界之演化(III)

The convergence of Southern Continents and Eurasia formed a large orogenic belt extending from Alps of Europe to Himalaya of Asia. In order to understand the collisonal process between Arabia and Eurasia, one needs to understand the convergent paths between these two plates first. Here we use newly published rotation poles from marine magnetic anomalies identifications from Red Sea and Gulf of Aden, and Atlantic Ocean, plus the opening of East African Rift system to calculate the relative motion between Arabia and Eurasia. Basically, one needs to calculate the following plate circuit: from Arabia to Somalia (opening of Red Sea and Gulf of Aden), Somalia to Africa (Nubia, opening of East African Rift system), Africa to North America (opening of Central Atlantic Ocean), and North America to Eurasia (opening of North Atlantic Ocean) to get the relative motions between Arabia and Eurasia. Looking at the calculated convergent rate and angle plots, there must be something going on around 25 Ma and 5 Ma. It’s no surprise for the slowdown of convergent rate at about 25 Ma since the information from magmatic study inferred a time for collision and crustal thickening. However, the crustal thickening from 10~5 Ma, might have caused anchoring effect to induce the Arabian Plate to move in a different direction (and therefore, the bent). Our calculating results indicate that there’s a positive correlation between plate convergence and magmatic activities. This correlation has been identified in the Tibetan collision and may also be possible to apply to the Arabia and Eurasia collision.