Coalescing upper-crust detachment faults as a major structural style in the Great Basin: Evidence from the White Pine and Horse Ranges, east-central Nevada, USA

2021 ◽  
Author(s):  
Robert D. Francis ◽  
Gregory J. Holk ◽  
Tor B. Lacy ◽  
Charles T. Walker
Keyword(s):  
Great Basin ◽  
Elevated Temperatures ◽  
Fundamental Problem ◽  
Essential Feature ◽  
Upper Crust ◽  
White Pine ◽  
East Central ◽  
Origin And Evolution ◽  
Detachment Faults ◽  
Detachment Faulting

ABSTRACT Determining the origin and evolution of basin-and-range geomorphology and structure in the western United States is a fundamental problem with global implications for continental tectonics. Has the extensional tectonic development of the Great Basin been dominated by steeply dipping (horst and graben) faulting or detachment faulting? The purpose of this paper is to provide evidence that attenuation due to multiple coalescing detachment faults has been a significant or dominant upper-crustal process in at least some areas of the Great Basin. We present mapping at a scale of 1:3000 and seismic refraction profiling of an area at the discontinuity between the White Pine and Horse Ranges, east-central Nevada, USA, which indicate the existence of a detachment rooted in an argillaceous ductile unit. This fault, which we call the Currant Gap detachment, coalesces with the previously mapped regional White Pine detachment. Our data suggest that the Currant Summit strike-slip fault at the surface, previously proposed to explain a nearly 2500 m east-west surface offset between the two ranges, likely does not exist. If a discontinuity exists at depth, it could be manifested at the surface by the undulating topography of the two coalescing detachments. On the other hand, offset domal uplifts in the two ranges would obviate the need for any lateral discontinuity at depth to explain the observed surface features. Our previous mapping of the White Pine detachment showed that it extends over the White Pine, Horse, and Grant Ranges and into Railroad Valley (total of 3000 km2). Accordingly, we propose a model of stacked, coalescing detachments above the metamorphic infrastructure; these detachments are regional and thus account for most of the basin-range relief and upper-crust extension in this area. An essential feature of our model is that these detachments are rooted in ductile units. Detachments that have been observed in brittle units could have initiated at a time when elevated temperatures or fluid flow enhanced the ductility of the rocks. The Currant Gap and White Pine detachments exhibit distinctive types of fluid-genetic silicified rocks. Study of such rocks in fault contacts could provide insights into the initiation and early history of detachment faulting as well as the migration of fluids, including petroleum.

Network Changes in Nitrile Rubber at Elevated Temperatures

1973 ◽  
Vol 46 (2) ◽  
pp. 483-503 ◽  
Author(s):  
T. C. P. Lee ◽  
S. H. Morrell
Keyword(s):  
Heat Resistance ◽  
Structural Changes ◽  
Elevated Temperatures ◽  
Essential Feature ◽  
Nitrile Rubber ◽  
Polymer Backbone ◽  
Thermal Changes ◽  
Effective Antioxidant ◽  
Cleavage Reactions ◽  
Crosslinking Reactions

Abstract The network analysis of the aged sulfur vulcanizates of nitrile rubber serves to re-emphasize the complexity of the structural changes which can occur at elevated temperatures. Three factors control the rate and degree of crosslinking in these systems. First there is the crosslink structure. An essential feature for heat resistance in sulfur compounds is that they should contain, as near as possible, 100 per cent monosulfide crosslinks. Systems which contain polysulfide crosslinks, and probably to a lesser extent disulfide crosslinks, are prone to purely thermal crosslink shortening or cleavage reactions. The physical effect of these thermal changes would be superimposed on the effects brought about by thermooxidative changes. Despite their thermal stability monosulfide crosslinks can oxidize and cleave, a process which will result in stress relaxation if the sample is held in tension or compression. Hence for truly inert systems one will have to turn to non-sulfur cure in conjunction with a suitable stabilizer. Because the results indicate that scission associated with chemistry at the monosulfide crosslink is reversible, this cleavage does not contribute to the change in modulus or hardening during aging. This brings in the second controlling factor. The degree and rate of hardening depends on the nature of the products of vulcanization, and also possibly on those species intermediate between crosslink and accelerator, the pendent accelerator groups. In acting as an antioxidant ZDMC is apparently oxidized to a new source of sulfur. The more heat resistant cadmate system contains no such products and also a minimum of pendent accelerator groups. This leads to the third factor—the added antioxidant. For its heat resistance the cadmate system relies on an antioxidant. It is this which stops crosslinking reactions through autooxidation of the polymer backbone. The efficiency with which the antioxidant (dioctyldiphenylamine) works suggests that there is a synergistic effect in operation, which in some way involves cadmium. Thus the best heat resistance will be obtained where the compound yields monosulfide crosslinks, an uncomplicated network structure, unreactive vulcanization products, and contains a highly effective antioxidant system. Many facets of the aging of nitrile rubber are still open to explanation. Not the least of these is why crosslinks formed during the aging of the TMTD/S vulcanizate, which, by reason of their reactivity to methyl iodide, are thought to be sulfidic, are not themselves oxidized in a manner similar to the original monosulfide crosslinks. Model compound studies would answer this and other questions.

scholarly journals Genetic Specificity in the White Pine-Blister Rust Pathosystem

2002 ◽  
Vol 92 (3) ◽  
pp. 278-280 ◽  
Author(s):  
Bohun B. Kinloch ◽  
Gayle E. Dupper
Keyword(s):  
North America ◽  
Great Basin ◽  
Single Gene ◽  
Low Frequency ◽  
White Pine Blister Rust ◽  
White Pine ◽  
Mendelian Segregation ◽  
Blister Rust ◽  
Sugar Pine ◽  
Bristlecone Pine

Four of eight white pine species native to western North America surveyed for resistance to white pine blister rust by artificial inoculation showed classical hypersensitive reactions (HR) at frequencies ranging from very low to moderate. Mendelian segregation, indicating a single dominant allele for resistance (Cr3), was observed in southwestern white pine (Pinus strobiformis), as it was previously in sugar pine (P. lambertiana, Cr1) and western white pine (P. monticola, Cr2). HR was present at a relatively high frequency (19%) in one of five bulk seed lot sources of limber pine (P. flexilis), and was also presumed to be conditioned by a single gene locus, by analogy with the other three species. HR was not found in whitebark pine (P. albcaulis), Mexican white pine (P. ayacahuite), foxtail pine (P. balfouriana), or Great Basin bristlecone pine (P. longaeva), but population and sample sizes in these species may have been below the level of detection of alleles in low frequency. When challenged by (haploid) inocula from specific locations known to harbor virulence to Cr1 or Cr2, genotypes carrying these alleles and Cr3 reacted differentially, such that inoculum virulent to Cr1 was avirulent to Cr2, and inoculum virulent to Cr2 was avirulent to Cr1. Neither of these two inocula was capable of neutralizing Cr3. Although blister rust traditionally is considered an exotic disease in North America, these results, typical of classic gene-for-gene interactions, suggest that genetic memory of similar encounters in past epochs has been retained in this pathosystem.

Irrigation in East Central California

1951 ◽  
Vol 17 (1Part1) ◽  
pp. 50-52
Author(s):  
Richard W. Patch
Keyword(s):  
Great Basin ◽  
Canal System ◽  
East Central ◽  
Canal Irrigation ◽  
Central California ◽  
Wasatch Mountains ◽  
Divergence Of Opinion ◽  
Natural Streams ◽  
Canal Systems ◽  
Area North

There is considerable divergence of opinion among authorities regarding the distribution of the practice of irrigation by the prehistoric Indians of the Southwest. Martin, Quimby, and Collier (1947, p. 168) write that the irrigation of the Hohokam of central and southern Arizona is the only known instance of canal irrigation in pre-Columbian North America. Thomas (1948, p. 10), however, writes that canal system irrigation was not limited to the area of the Hohokam but that “in many ravines and valleys in Arizona, New Mexico, Colorado, Utah and Southern California are found the remains of canal systems which tapped the natural streams and carried water to the numerous small farms.” Wittfogel (Wittfogel and Goldfrank, 1943), has assembled published evidences of irrigation in the Anasazi area, north of the Hohokam, such as its practice west of the Wasatch Mountains in the Great Basin portion of Utah, described by Steward.

Some results of COCORP seismic reflection profiling in the Grenville-age Adirondack Mountains, New York State

1985 ◽  
Vol 22 (2) ◽  
pp. 141-153 ◽  
Author(s):  
S. L. Klemperer ◽  
L. D. Brown ◽  
J. E. Oliver ◽  
C. J. Ando ◽  
B. L. Czuchra ◽  
...  
Keyword(s):  
New York ◽  
Lower Crust ◽  
Seismic Reflection ◽  
New York State ◽  
Three Dimensional ◽  
Upper Crust ◽  
Adirondack Mountains ◽  
East Central ◽  
York State ◽  
Seismic Reflection Profiling

COCORP deep seismic reflection profiling in the Adirondack Mountains of northern New York State has revealed a prominent zone of layered reflectors in the lower crust of the east-central Adirondacks. The strong, layered reflectors (here termed the Tahawus complex) occur between 18 and 26 km depth, beneath the sparsely reflective, granulite-grade, surface terrane, which has been uplifted from depths greater than 20 km. The Tahawus complex apparently represents layered rocks of some type in the lower crust of the Adirondacks. Possibilities include gneissic layering, cumulate igneous layering, a layered sill complex, and underthrust sedimentary strata, The Tahawus complex may be spatially coincident with a previously detected, high-conductivity zone in the lower crust, suggesting that either unusual mineralogies or interstitial electrolytes are present in the Tahawus complex. In contrast to layered reflections discovered in the lower crust of the east-central Adirondacks and southeast of the Adirondacks, cross-cutting and discontinuous reflections are recorded from the upper crust on all the COCORP Adirondack lines, including lines in both the Adirondack Highlands and Lowlands. Available three-dimensional control suggests that reflections in the upper crust of the central Adirondacks are parallel to, and hence may be related to, the folded gneisses mapped at the surface. Shallow events are also observed on a COCORP profile close to the epicenter of the 7 October 1983 magnitude 5.2 earthquake in the central Adirondacks, but their relation to the earthquake is uncertain.

Investigation of upper crust anisotropy in Ghaen-Birjand region, east-central Iran

2004 ◽  
Vol 17 (5) ◽  
pp. 518-525 ◽  
Author(s):  
Mohammad-Reza Gheitanchi ◽  
Zoya Zarifii
Keyword(s):  
Central Iran ◽  
Upper Crust ◽  
East Central

Evidence of temperature depression and hydrological variations in the eastern Sierra Nevada during the Younger Dryas Stade

2008 ◽  
Vol 70 (2) ◽  
pp. 131-140 ◽  
Author(s):  
Glen M. MacDonald ◽  
Katrina A. Moser ◽  
Amy M. Bloom ◽  
David F. Porinchu ◽  
Aaron P. Potito ◽  
...  
Keyword(s):  
Sierra Nevada ◽  
Great Basin ◽  
North Atlantic ◽  
Younger Dryas ◽  
East Central ◽  
The North ◽  
Dry Conditions ◽  
Maximum Temperatures ◽  
Temperature Depression ◽  
The North Pacific

AbstractSediment records from two lakes in the east-central Sierra Nevada, California, provide evidence of cooling and hydrological shifts during the Younger Dryas stade (YD; ~ 12,900–11,500 cal yr BP). A chironomid transfer function suggests that lake-water temperatures were depressed by 2°C to 4°C relative to maximum temperatures during the preceding Bølling–Allerød interstade (BA; ~ 14,500–12,900 cal yr BP). Diatom and stable isotope records suggest dry conditions during the latter part of the BA interstade and development of relatively moist conditions during the initiation of the YD stade, with a reversion to drier conditions later in the YD. These paleohydrological inferences correlate with similar timed changes detected in the adjacent Great Basin. Vegetation response during the YD stade includes the development of more open and xeric vegetation toward the end of the YD. The new records support linkages between the North Atlantic, the North Pacific, and widespread YD cooling in western North America, but they also suggest complex hydrological influences. Shifting hydrological conditions and relatively muted vegetation changes may explain the previous lack of evidence for the YD stade in the Sierra Nevada and the discordance in some paleohydrological and glacial records of the YD stade from the western United States.

scholarly journals The Mesozoic Tectonic Dynamics and Chronology in the Eastern North China Block

2012 ◽  
Vol 2012 ◽  
pp. 1-11 ◽  
Author(s):  
Quanlin Hou ◽  
Qing Liu ◽  
Hongyuan Zhang ◽  
Xiaohui Zhang ◽  
Jun Li
Keyword(s):  
North China ◽  
Late Triassic ◽  
Upper Crust ◽  
North China Block ◽  
Late Mesozoic ◽  
Detachment Faults ◽  
The North ◽  
North Part ◽  
Strong Compression ◽  
Tectonic System

Mesozoic tectonic events in different areas of the eastern North China Block (NCB) show consistency in tectonic time and genesis. The Triassic collision between NCB and Yangtze results in the nearly S-N strong compression in the Dabie, Jiaodong, and west Shandong areas in Middle Triassic-Middle Jurassic. Compression in the Yanshan area in the north part of NCB was mainly affected by the collision between Mongolia Block and NCB, as well as Siberia Block and North China-Mongolia Block in Late Triassic-Late Jurassic. However, in the eastern NCB, compressive tectonic system in Early Mesozoic was inversed into extensional tectonic system in Late Mesozoic. The extension in Late Mesozoic at upper crust mainly exhibits as extensional detachment faults and metamorphic core complex (MCC). The deformation age of extensional detachment faults is peaking at 120–110 Ma in Yanshan area and at 130–110 Ma in the Dabie area. In the Jiaodong area eastern to the Tan-Lu faults, the compression thrust had been continuing to Late Mesozoic at least in upper crust related to the sinistral strike slipping of the Tan-Lu fault zone.The extensional detachments in the eastern NCB would be caused by strong crust-mantle action with upwelling mantle in Late Mesozoic.

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