Late Cenozoic Displacement Transfer Analysis Within Deep Springs Valley, Eastern California With Gravity Modeling
The northern segment of the Eastern California Shear Zone (ECSZ) is characterized by rightlateral transtension accommodated on a network of north-northwest and northwest striking dextral transcurrent faults connected by north-northeast striking normal faults. North-northeast faults bounding Deep Springs Valley, California, transfer displacement from the Owens ValleyWhite Mountain fault system in eastern California eastward to the Fish Lake Valley (FLV) fault. The FLV fault is the northern segment of the most active structure in the ECSZ and marks the eastern boundary of the zone of right-transtensional displacement east of the Sierra Nevada. Deep Springs Valley is 22 km long and 5 km wide and is bounded by a prominent northnortheast striking fault on the southeast that, to the northeast, emanates into six east-northeast splays transferring displacement east. The northwest boundary of the basin is marked by a more subdued north-northeast trending fault zone stretching the length of the basin. 381 gravity stations at a nominal 300 m spacing were collected as part of a gravity survey within the basin. The residual gravity data shows a -13.2 mGal gravity low in the southeastern part of the basin that gradually increases to -4.7 mGal to the northeast. The residual gravity values correspond to depths of about 0.85 and 0.2 km, respectively. Restoration to a pre-extensional datum, using an extension direction of N65W, yields a cumulative horizontal extension of ~1930 m across the basin fault system, which corresponds to an equal amount of right lateral displacement transferred to the FLV fault system. The estimated extension rate of 0.58 mm/yr since 4 Ma or 1.1 mm/yr if displacement was initiated at 1.7 Ma.