Plate Motion Statistics and Relation of Propagation and Overlap for the Juan de Fuca Ridge

组成地球外壳的岩石圈板块在大洋中脊(扩张中心)通过火山作用形成，在那里，火成岩物质或多或少对称地添加到与大洋中脊接壤的每个板块中。这种生长过程伴随着海脊两侧两个板块之间的相对运动--这种运动可以通过对大洋中脊上方海面观测到的电磁异常的研究来确定。在很短的地质时期(几百万年)内，这种相对运动可以用围绕固定在每个板块上的一个点(极)的自转来描述。在较长的一段时间内，这种运动更加复杂，并伴随着大洋中部扩张中心形态的变化，这种变化表现为重叠的扩张中心和伸展的裂缝。这个项目调查了华盛顿-俄勒冈州海岸外的扩展中心胡安德·富卡山脊的这一过程的细节。威尔逊计划确定胡安德富卡板块相对于太平洋板块的运动置信限的修正后的旋转极。在这一过程中，他将制作计算机模型，以演示重叠传播中心和传播裂隙的发展。他还将尝试确定在多长时间内相对板块运动可以用样本旋转来描述。

Lithospheric plates that compose the outer shell of the earth form by volcanic processes at mid-ocean ridges (spreading centers) where igneous material is added more or less symmetrically to each plate which borders on the mid-ocean ridge. This growth process is accompanied by relative motion between the two plates on either side of the ridge crest-motion that can be determined from a study of amgnetic anomalies observed at the sea surface over the mid-ocean ridge. Over a short period of geologic time ( few million years) this relative motion can be described in terms of rotation about a point (pole) that remains fixed to each plate. Over longer periods of time the motion is moe complicated and is accompanied by changes in the configuration of the mid-ocean spreading center, changes which are manifest as overlapping spreading centers and proagating rifts. %%% This project investigates the details of this process for the Juan de Fuca Ridge, a spreading center off the Washington- Oregon coast. Wilson plans to determine a revised rotation pole with confidence limits for motion of the Juan de Fuca plate with respect to the Pacific plate. In the process he will make computer modesl to demonstarate the development of overlapping spreading centers and propagating rifts. He will also attempt to determine over what interval the relative plate motion can be described in terms of a sample rotation.