Seismotectonics of mid-ocean ridge propagation
- 页数：75 p. :
- 第一责任说明：Jacqueline Suzanne Floyd.
- 分类号：a260 ; a242.1
MARC全文
62h0020595 20140522141431.0 cr un||||||||| 100928s2003 xx ||||f|||d||||||||eng | CNY371.35 (UnM)AAI3104799 UnM UnM NGL a260 ; a242.1 Floyd, Jacqueline Suzanne. Seismotectonics of mid-ocean ridge propagation [electronic resource] / Jacqueline Suzanne Floyd. 75 p. : digital, PDF file. Source: Dissertation Abstracts International, Volume: 64-09, Section: B, page: 4253. ; Adviser: John C. Mutter. Thesis (Ph.D.) -- Columbia University, 2003. This dissertation investigates the rifting-spreading transition of two propagating mid-ocean spreading centers within actively rifting lithosphere, Woodlark Basin and Hess Deep. Hess Deep is a 5.4 km-deep oceanic rift basin at the westernmost tip of the Galapagos Spreading Center where it meets the East Pacific Rise at the Galapagos Triple Junction. Hydroacoustic seismicity data recorded over 200 earthquakes in Hess Deep that reveal earthquake and deformation patterns that are similar to those found in the process zone of laboratory-scale propagating tensile cracks. Seismicity and deformation patterns observed in Hess Deep are consistent with those from crack tip process zones Process zone deformation releases large crack tip stresses predicted by theoretical fracture mechanics and allows stable propagation to occur; thus, viscous suction or other forces are not required to balance the crack tip stress as proposed by previous investigators. The western Woodlark Basin of Papua New Guinea is the site of a major low-angle detachment fault immediately ahead of the westward propagating spreading center. We present the results of two studies of this fault: one using reflection seismology to image the fault zone velocity structure and composition, and one using deep crustal refraction seismology to image the large-scale velocity structure of the fault and surrounding crust. Results from genetic algorithm inversion of seismic reflection data show that the fault contains a frictionally weak fault gouge layer and fluids, while results from seismic tomography show that the fault is a major rift boundary between the northern and southern rift margins of the western Woodlark Basin. We conclude that favorable conditions exist for frictional slip at angles of 30° or less and that this will be the last fault to form before the crust completely rifts apart to create new oceanic crust and lithosphere. The morphology of the rifting-spreading transitions in Woodlark Basin and Hess Deep are similar in structure and spatial scale, suggesting that the results from one rift may be applicable to the other with appropriate modifications for pre-rift crustal structure and regional tectonic setting. Seismology. ; Marine geophysics. ; Submarine geology. ; Rifts (Geology) ; Earthquakes. ; Plate tectonics. aMutter, John C. aCN bNGL http://pqdt.bjzhongke.com.cn/Detail.aspx?pid=qdZEXEMiKvc%3d NGL Bs617 rCNY371.35 ; h1 xhbs1002