Map showing Quaternary and Pliocene faults in the Silver City 1° x 2° quadrangle and the Douglas 1° x 2° quadrangle, southeastern Arizona and southwestern New Mexico (original) (raw)
Related papers
Open-file report /, 1992
Lineaments and faults in Quaternary and late Tertiary deposits in the southern part of the Walker Lane are potentially active and form patterns that are anomalous with respect to the typical fault patterns in most of the Great Basin. Little work has been done to identify and characterize these faults, with the exception of those in the Death Valley-Furnace Creek fault zone (DVFCFZ) and those in and near the Nevada Test Site. This report includes two quadrangle maps and portions of four others at a scale of 1:100,000; these maps complete a project (previous maps include U.S.G.S. Open-File Reports 90-41 and 90-500) to summarize the existing knowledge about these lineaments and faults within 100 km of the potential high-level nuclear waste repository at Yucca Mountain, based on extensive aerial-photo interpretation, limited field investigations, and published geologic maps. The map area can be divided into two areas. The principal area, covering all of the map area except the southeast corner in the Las Vegas quadrangle, contains mainly northtrending lineaments and faults with a lesser number of east-to northeast-trending faults and a few inactive northwest-trending faults. The north-trending features include rangebounding faults and scarps, faults within volcanic plateaus (Pahute Mesa), and some clusters of faults and scarps on valley floors. The orientations and sense of slip within this domain indicate that the least principal stress direction is northwest-southeast. In the southeastern area, faults and lineaments associated with the Pahrump fault zone trend northwest and north; in this domain, the least principal stress direction is about east-west. Most of the area, and particularly the eastern part of the principal area, has previously been considered to be tectonically inactive, at least since the late Miocene. The abundance of steep straight range-front segments and scarps in Quaternary deposits, however, indicates that faulting and extension in this area are still active. 117°-37° 30' ,-36° 30' Figure l.-Sketch map showing physiography, geographic features, principal fault zones, and boundaries of plates.
Geosphere, 2017
We use new and existing data to compile a record of ~18 latest Quaternary large-magnitude surface-rupturing earthquakes on 7 fault zones in the northwestern Basin and Range Province of northwestern Nevada and northeastern California. The most recent earthquake on all faults postdates the ca. 18-15 ka last glacial highstand of pluvial Lake Lahontan and other pluvial lakes in the region. These lacustrine data provide a window in which we calculate latest Quaternary vertical slip rates and compare them with rates of modern deformation in a global positioning system (GPS) transect spanning the region. Average vertical slip rates on these fault zones range from 0.1 to 0.8 mm/yr and total ~2 mm/yr across a 265-km-wide transect from near Paradise Valley, Nevada, to the Warner Mountains in California. We converted vertical slip rates to horizontal extension rates using fault dips of 30°-60°, and then compared the extension rates to GPS-derived rates of modern (last 7-9 yr) deformation. Our preferred fault dip values (45°-55°) yield estimated longterm extension rates (1.3-1.9 mm/yr) that underestimate our modern rate (2.4 mm/yr) by ~21%-46%. The most likely sources of this underestimate are geologically unrecognizable deformation from moderate-sized earthquakes and unaccounted-for coseismic off-fault deformation from large surface-rupturing earthquakes. However, fault dip values of ≤40° yield long-term rates comparable to or greater than modern rates, so an alternative explanation is that fault dips are closer to 40° than our preferred values. We speculate that the large component of right-lateral shear apparent in the GPS signal is partitioned on faults with primary strike-slip displacement, such as the Long Valley fault zone, and as not easily detected oblique slip on favorably oriented normal faults in the region.
Holocene faulting on the Saline River fault zone, Arkansas, along the Alabama-Oklahoma transform
A fundamental goal of intraplate tectonics research is to understand the role of crustal discontinuities in the distribution of Quaternary surface ruptures. Geophysi-cal studies of southern North America on the Gulf of Mexico Coastal Plain reveal a buried Cambrian craton margin (Alabama-Oklahoma transform) that strikes southeast beneath Mesozoic and Cenozoic passive-margin sediments and Paleozoic thrust sheets. Seismic-refl ection profi les show a graben system (Saline River fault zone) related to an episode of Triassic rifting above this transform margin during initial opening of the Gulf of Mexico. Post-Triassic reactivation of the Saline River fault zone produced normal and reverse faulting and strike-slip fl ower structures that can be linked to Quaternary surface deformation. We investigated surface and shallow Quaternary faulting along the Saline River fault system in south-central North America. Our fi eld sites show late Pleistocene to
Open-file report /, 1991
Faults and fault-related lineaments in Quaternary and late Tertiary deposits in the southern part of the Walker Lane are potentially active and form patterns that are anomalous compared to those in most other areas of the Great Basin. Two maps at a scale of 1:100,000 summarize information about lineaments and faults in the area around and southwest of the Death Valley-Furnace Creek fault system based on extensive aerial-photo interpretation, limited field investigations, and published geologic maps. Darwin Hills 1:100,000 quadrangles. (1) The Death Valley-Furnace Creek fault system and (2) the Hunter Mountain fault zone are northwest-trending right-lateral strike-slip fault zones. (3) The Panamint Valley fault zone and associated Towne Pass and Emigrant faults are north-trending normal faults. The intersection of the Hunter Mountain and Panamint Valley fault zones is marked by a large complex of faults and lineaments on the floor of Panamint Valley. Additional major faults include (4) the north-northwest-trending Ash Hill fault on the west side of Panamint Valley, and (5) the north-trending range-front Tin Mountain fault,on the west side of the northern Cottonwood Mountains. There are three major fault zones and two principal faults in the Saline Valley and The most active faults at present include those along the Death Valley-Furnace Creek fault system, the Tin Mountain fault, the northwest and southeast ends of the Hunter Mountain fault zone, the Ash Hill fault, and the fault bounding the west side of the Panamint Range south of Hall Canyon. Several large Quaternary landslides on the west sides of the Cottonwood Mountains and the Panamint Range apparently reflect slope instability due chiefly to rapid uplift of these ranges.
Style and timing of Holocene surface faulting on the Meers fault, southwestern Oklahoma
Geological Society of America Bulletin, 1990
Stratigraphic relations and radiocarbon ages of deposits exposed in several trenches and excavations help to establish the timing, sense of slip, and style of the deformation that resulted from late Holocene surface faulting on the Meers fault in southwestern Oklahoma. The eastern half of the scarp is formed on relatively ductile Permian Hennessey Shale and Quaternary alluvium, whereas the western half is formed on well-lithified, relatively brittle Permian Post Oak Conglomerate in the Slick Hills. At Canyon Creek on the eastern half of the scarp, the shale and alluvium in two trenches are deformed mainly by monoclinal warping. These trenches contain stratigraphic evidence of one surface-faulting event that produced about 3 m of throw. At this site, the amount of throw in middle Holocene and middle Pleistocene deposits is similar. Lateral displacement is difficult to detect in these trenches, most likely because of plastic deformation in the shale and alluvium. In contrast, trenches and excavations on the western half of the scarp show that the Holocene surface faulting produced at least as much lateral as vertical displacement At two sites, the scarp has dammed small gullies and ponded fine-grained alluvium upslope from the scarp. The channels of the gullies at these ponded-alluvium sites have been separated 3-5 m left-laterally since they were dammed. The lateral displacement on the gullies is 3.3 to 1.6 times as much as the vertical displacement. In a pit excavated into the colluvium on the downthrown side of the scarp, subhorizonta! striae on conglomerate clasts along the fault plane provide evidence of nearly pure strike-slip movement. The age of the striae is unknown, but they are believed to be Quaternary in age because it is unlikely that such delicate striae could be preserved in soluble carbonate rock in a near-surface weathering environment for many hundreds of thousands of years. Multiple radiocarbon ages of soil-humus samples from the Canyon Creek trenches and the ponded-alluvium sites show that the last surface faulting occurred 1,200-1,300 yr ago. Limited geologic evidence, however, indicates a long-term recurrence interval on the order of 100,000 yr or more. The youthful surface faulting compared to the apparently long recurrence interval presents a difficult problem for regional seismichazard assessments. Hazard assessments that rely on the long-term slip rate might seriously underestimate the hazard if the behavior of the fault is characterized by a temporal clustering of events, and if the late Holocene surface faulting signals the beginning of a period of frequent faulting. Conversely, if strain accumulates steadily on the Meers fault and is released regularly over time intervals of 100,000 yr or more, then the hazard may be low because much of the stored strain was released only about 1,000 yr ago. Improved earthquake-hazard assessments in much of the central United States and in stable intraplate settings worldwide require a better understanding of the long-term and short-term behavior of seismogenic intraplate faults.
The mineral resources of western Utah's East Tintic mining district were influenced by three major geologic events: the Mesozoic Sevier orogeny, Paleogene magmatism, and late Neogene Basin and Range extension. In this paper we present a detailed analysis of the structural history of these geologic events. The focus of our study was the Allens Ranch 7.5' quadrangle, which lies in the northern East Tintic Mountains near the eastern margin of the Great Basin of central Utah. The focus area lies ~75 km behind the front of the Provo salient of the Sevier deformation belt. Based on the orientations of folds and fold axes, the maximum local paleostress direction for the Sevierage East Tintic fold and thrust system was 82° (between 80° and 100°) with fold axes oriented at ~350°.