scholarly journals Regional structural setting of Yucca Mountain, southwestern Nevada, and late Cenozoic rates of tectonic activity in part of the southwestern Great Basin, Nevada and California

1984 ◽  
Author(s):  
W.J. Carr
1992 ◽  
Vol 82 (1) ◽  
pp. 164-174
Author(s):  
James N. Brune ◽  
Walter Nicks ◽  
Arturo Aburto

Abstract We operated a microearthquake array in the neighborhood of the proposed high-level nuclear waste repository at Yucca Mountain, Nevada. The array consists of four high-gain (up to 34 million), narrow band (25 Hz) telemetered stations. Based on approximate magnitude calibration of the array we expect during quiet periods, for distances less than 15 km, complete recording of events at Yucca Mt. for M ≧ −1. We have operated the four stations for 12-hour periods overnight between August and October 1990 and intermittently afterward, until April 1991, when we began more or less continuous operation. The pattern of microearthquake activity confirms the existence of a zone of seismic quiescence in the vicinity of proposed repository. We recorded only about 10 events with S-P times of less than 3 sec (D < 24 km). Most events had S-P times between 3 and 6.5 sec, consistent with the higher seismic activity at distances between 24 and 52 km observed by Rogers et al. (1987) and Gomberg (1991). Oliver et al. (1966) found, contrary to what has been observed by us for Yucca Mountain, that in seismically active areas most of the events had S-P times of less than 3 sec. We confirmed this expectation for four microearthquake stations near Mammoth Lakes, where we observed microearthquake rates of over 100 per day, most with S-P times of less than 3 sec. Extrapolation of seismicity data from the Southern Great Basin Seismic Network confirms the low microearthquake activity in the immediate vicinity of Yucca Mountain.


2011 ◽  
Vol 497 (1-4) ◽  
pp. 45-56 ◽  
Author(s):  
Zhengle Chen ◽  
Jian Liu ◽  
Hongliang Gong ◽  
Fengbin Han ◽  
Stephanie Marion Briggs ◽  
...  

2020 ◽  
Author(s):  
Vincent Godard ◽  
André Salgado ◽  
Lionel Siame ◽  
Jules Fleury ◽  
Team Aster

<p>Understanding the degree of sensitivity of the Earth Surface to past climate changes is key to assess the strength of postulated links between weathering, denudation, rock uplift and climate. Numerous studies have investigated the response of surface processes to the evolution through time of temperature and precipitation, in various settings and over different time periods. In particular, an important question still actively debated concerns whether or not Late Cenozoic climate change had an effective impact on denudation rates. It is noteworthy that this Late Cenozoic climatic evolution is often described as a long-term cooling over several Ma. However, although it has been postulated to be an important control on this response, the impact of its orbitally-controlled high-frequency component has been less investigated.</p><p>Studies focusing on climate-denudation links have often been carried out in regions of high tectonic activity. Therefore, they encountered associated significant limitations, such as: (1) high denudation rates that reach the analytical limits of many measurement methods; (2) stochastic events introducing a high degree of variability in the denudation signal; and, (3) high rates of tectonic uplift that can limit the sensitivity to the low-frequency component of the climatic boundary condition. Less active tectonic settings with lower denudation rates may thus provide conditions allowing to focus specifically on the coupling between climate variations and surface processes. Additionally, approaches combining different cosmogenic nuclides have proven to be very effective to unravel changes in surface processes over several time scales.</p><p>We present a new cosmogenic nuclides dataset from the Sera do Cipo range in Minas Gerais, Brazil. The core of the range is made of resistant quarzite bedrock with a relief of 500 m with respect to the surrounding low lands, and reported denudation rates are <10 m/Ma. Streams sediments from small catchments near the summit divide, as well as clasts derived from massive quartz veins at hilltop locations, were sampled. Both <sup>10</sup>Be and <sup>26</sup>Al concentrations were measured in the collected samples, as in such slow denudation settings the ratio between the two nuclides is sensitive to changes in denudation rates through time. A high-resolution (1 m) Digital Elevation Models was also produced from tri-stereo Pléiades satellite images. This allows to compute high resolution metrics such as hilltop curvature at the sampling sites. Hilltop denudation rates display a strong positive correlation with curvature. <sup>26</sup>Al/<sup>10</sup>Be values significantly departing from the theoretical steady state denudation ratio are interpreted at hilltop sites as reflecting the fluctuation of denudation through time. Concerning the catchments samples, the determined ratio can also be impacted by the sediment transport history along hillslopes. Combining cosmogenic nuclides and high-resolution topographic datasets, the measured concentrations were inverted to constrain the variation of denudation over the last 2 Ma. We observe a significant change in the denudation regime at 1 Ma, with different kind of responses between ridges and small catchments across the landscape.</p>


Tectonics ◽  
1996 ◽  
Vol 15 (3) ◽  
pp. 660-676 ◽  
Author(s):  
John C. Behrendt ◽  
Richard Saltus ◽  
Detlef Damaske ◽  
Anne McCafferty ◽  
Carol A. Finn ◽  
...  

2019 ◽  
Vol 23 (4) ◽  
pp. 283-291
Author(s):  
Dejie Deng ◽  
Changliu Wang ◽  
Peihao Peng

Based on field geological survey and stratigraphic profile survey in the eastern margin of the Qinghai-Tibet Plateau, the basic characteristics and evolution of geological structure in the eastern margin of the Qinghai-Tibet Plateau are studied. The Dongyuan area of the Qinghai-Tibet Plateau is divided into the late Cenozoic period and the current period. During the Late Cenozoic, the Pliocene Xigeda lacustrine deposits develops from 4.2 MaBP to 2.6 MaBP, with 9 cold-warm climate change stages. There are 4.3 MaBP old glacial period in this area, and 5 extreme paleoclimate events in Quaternary. At present, the horizontal movement intensity and mode of different tectonic zones are determined by the northward extrusion, eastward extrusion and rotation around the eastern tectonic junction in the study area, and the stages of the movement state changing with time are related to the gestation and occurrence of extra-large earthquakes. At present, the three-dimensional crustal movement shows that the tectonic activity differentiation of mountain and basin, which is related to tectonic dynamic environment and deep material activity, is related to the compression, shortening and uplift of plateau mountain and the extension and subsidence of basin, reflecting the inheritance of neotectonic activity. Through practical analysis, it is found that the eastern margin of the Qinghai-Tibet Plateau is composed of Minshan fault block and Longmenshan structural belt. The left-lateral dislocation of Minjiang fault is roughly the same as the vertical dislocation. In Longmenshan tectonic belt, the right-lateral dislocation of Maowen-Wenchuan fault, Beichuan-Yingxiu fault and other main faults is the same as the vertical dislocation.


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