Using the World&#39;s Fastest Slipping Normal Fault to Understand the Mechanics of Low-angle Normal Faults

GSTDTAP

项目编号	1524729
	Using the World's Fastest Slipping Normal Fault to Understand the Mechanics of Low-angle Normal Faults
	Laura Wallace
主持机构	University of Texas at Austin
项目开始年	2015
	2015-08-01
项目结束日期	2018-07-31
资助机构	US-NSF
项目类别	Continuing grant
项目经费	290077(USD)
国家	美国
语种	英语
英文摘要	Normal faults play a major role in stretching the earth?s crust and generating earthquakes, yet their mechanics are poorly understood. Determining their strength, seismogenic potential, and why some may slip rapidly or accumulate large displacements are key to understanding not only rifted plate margins - with their associated mineral resources and earthquake hazard - but also basic fault mechanics. Rock deformation experiments predict that normal faults should initiate at steep dips of about 60-70º and that they should frictionally lock up at dips less than 30-45º. However, geologists have long observed major low-angle normal faults in the rock record. This observation and the lack of normal fault earthquakes with dips less than 30-45º suggest that natural faults may be weaker than experiments indicate. Resolving this apparent mechanical paradox remains at the center of a debate about the strength of mature faults. To address the mysteries of slip on low-angle normal faults, this multi-disciplinary study of the best-exposed and fastest slipping of the few active examples known on Earth, the Mai'iu Fault in the Woodlark Rift of Papua New Guinea, uses GPS, thermochronometric, structural geologic and geomorphic observations, and modeling to test current ideas of low-angle fault mechanics. The project would advance desired societal outcomes through: (1) full participation of women in STEM; (2) increased public scientific literacy and public engagement with science and technology through outreach to Papua New Guinea native populations; (3) development of a globally competitive STEM workforce through the training of graduate students; and (4) increased partnerships through international collaboration with New Zealand scientists. The project is supported by the Tectonics Program and NSF's International Science and Engineering program. As the world's fastest slipping active low-angle normal fault, the Mai'iu fault represents a world class opportunity to resolve controversies regarding the mechanics and evolution of low-angle normal faults. The Mai'iu Fault slips at 6-10 mm/year, and its smooth, domal surface is exposed in the landscape for more than 20 km, yielding a rare natural laboratory of an active and rapidly slipping low-angle normal fault in a continental rift. Through multidisciplinary data acquisition and modeling efforts, the University of Texas team in collaboration with New Zealand scientists will address the following hypotheses: (1) slip on low-angle normal faults can occur at cm/year rates on intrinsically weak planes; (2) slip on low-angle normal faults can occur by aseismic creep; (3) low-angle normal faults undergo temporal variations in slip rate; and (4) normal faults on the continents can acquire large displacements through the rolling hinge process. The research team employs: (1) campaign GPS to determine contemporary slip rates and whether or not the fault is creeping or locked; (2) geochronology and thermochronology ((U-Th)/He, fission track, multi-diffusion domain K-feldspar 40Ar/39Ar) to evaluate the evolution of low-angle normal faults, and variations in exhumation/slip rates through time; (3) cosmogenic radionuclide studies to evaluate Quaternary slip rates of the Mai'iu Fault; (4) structural geology to identify slip mechanisms on the fault and structural evolution of the dome; and (5) geodynamical modeling to integrate and interpret the various data sets.
来源学科分类	Geosciences - Earth Sciences
文献类型	项目
条目标识符	http://119.78.100.173/C666/handle/2XK7JSWQ/68399
专题	环境与发展全球科技态势
推荐引用方式 GB/T 7714	Laura Wallace.Using the World's Fastest Slipping Normal Fault to Understand the Mechanics of Low-angle Normal Faults.2015.