Candelaria and other left-oblique slip faults of the Candelaria region, Nevada

Speed, R. C.; Cogbill, Allen H.

doi:10.1130/0016-7606(1979)90<149:caolsf>2.0.co;2

Cited by 20 publications

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“…The trace of the Candelaria fault zone appears on the maps of Dohrenwend [1982a], Stewart [1981, 1984], and Stewart et al [1982]. Speed and Cogbill [1979] pointed out the active nature of the fault, and combined observations of fault striae and measurable throw of Pliocene basalts to estimate a cumulative 900 m of net left‐oblique slip since 2.8 Ma, about 0.3 mm/yr. (Figure 12).…”

Section: Observations: Active Faults Of the Central Walker Lanementioning

confidence: 99%

Active faulting in the Walker Lane

2005

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Deformation across the San Andreas and Walker Lane fault systems accounts for most relative Pacific–North American transform plate motion. The Walker Lane is composed of discontinuous sets of right‐slip faults that are located to the east and strike approximately parallel to the San Andreas fault system. Mapping of active faults in the central Walker Lane shows that right‐lateral shear is locally accommodated by rotation of crustal blocks bounded by steep‐dipping east striking left‐slip faults. The left slip and clockwise rotation of crustal blocks bounded by the east striking faults has produced major basins in the area, including Rattlesnake and Garfield flats; Teels, Columbus and Rhodes salt marshes; and Queen Valley. The Benton Springs and Petrified Springs faults are the major northwest striking structures currently accommodating transform motion in the central Walker Lane. Right‐lateral offsets of late Pleistocene surfaces along the two faults point to slip rates of at least 1 mm/yr. The northern limit of northwest trending strike‐slip faults in the central Walker Lane is abrupt and reflects transfer of strike‐slip to dip‐slip deformation in the western Basin and Range and transformation of right slip into rotation of crustal blocks to the north. The transfer of strike slip in the central Walker Lane to dip slip in the western Basin and Range correlates to a northward broadening of the modern strain field suggested by geodesy and appears to be a long‐lived feature of the deformation field. The complexity of faulting and apparent rotation of crustal blocks within the Walker Lane is consistent with the concept of a partially detached and elastic‐brittle crust that is being transported on a continuously deforming layer below. The regional pattern of faulting within the Walker Lane is more complex than observed along the San Andreas fault system to the west. The difference is attributed to the relatively less cumulative slip that has occurred across the Walker Lane and that oblique components of displacement are of opposite sense along the Walker Lane (extension) and San Andreas (contraction), respectively. Despite the gross differences in fault pattern, the Walker Lane and San Andreas also share similarities in deformation style, including clockwise rotations of crustal blocks leading to development of structural basins and the partitioning of oblique components of slip onto subparallel strike‐slip and dip‐slip faults.

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Section: Observations: Active Faults Of the Central Walker Lanementioning

confidence: 99%

Active faulting in the Walker Lane

2005

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“…Where observable, fault planes, or minor planes associated with a fault trace, dip steeply, generally greater than 65°. These results suggest that movement on these faults was not pure (Speed and Cogbill, 1979a), the area north of the Volcanic Hills, in the Columbus and Miller Mountain quadrangles (Stewart, 1979), and the northern Silver Peak Range (Robinson and others, 1976). In addition, older Quaternary fault scarps across Big Smoky Valley, at the base of Lone Mountain have similar trends of N. 65 E. and N. 20 E. (Davis and Vine, 1979, p. 422).…”

Section: Along Walker Lane Which Merges Southward Into the Las Vegasmentioning

confidence: 95%

“…The zone of intensely folded rocks may be analogous to similarly trending folds and associated compressional features in the Candelaria Hills (Speed and Cogbill, 1979a). Those authors describe local concentrations of folds with northwest-trending axial traces, that lie along the north wall of the east-trending Candelaria fault system.…”

Section: Along Walker Lane Which Merges Southward Into the Las Vegasmentioning

confidence: 96%

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Geology of a part of the southern Monte Cristo Range, Esmeralda County, Nevada

Moore¹

1981

Open-File Report

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“…The dominant post-mineralisation structures are extensive systems of east-to northeast-striking, Oligocene and younger, BasinRange style faults (Page 1959;Speed and Cogbill 1979b). They dislocate all lithological units and are particular/y abundant throughout the main mineralised area (Figs.…”

Section: Regional Setting and Deposit Geologymentioning

confidence: 99%

The Candelaria silver deposit, Nevada ? preliminary sulphur, oxygen and hydrogen isotope geochemistry

et al. 1994

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The pre-Cenozoic geology at Candelaria, Nevada comprises four main lithologic units: the basement consists of Ordovician cherts of the Palmetto complex; this is overlain unconformably by Permo-Triassic marine clastic sediments (Diablo and Candelaria Formations); these are structurally overlain by a serpentinitehosted tectonic m~lange (Pickhandle/Golconda allochthon); all these units are cut by three Mesozoic felsic dike systems. Bulk-mineable silver-base metal ores occur as stratabound sheets of vein stockwork/disseminated sulphide mineralisation within structurally favourable zones along the base of the Pickhandle allochthon (i.e. Pickhandle thrust and overlying ultramafics/mafics) and within the fissile, calcareous and phosphatic black shales at the base of the Candelaria Formation (lower Candelaria 'shear'). The most prominent felsic dike system -a suite of Early Jurassic granodiorite porphyries -exhibits close spatial, alteration and geochemical associations with the silver mineralisation. Disseminated pyrites from the bulk-mineable ores exhibit a 634S range from -0.3%o to + 12.1%o (mean 634S = + 6.4 + 3.5%o, la, n = 17) and two sphalerites have 6348 of + 5.9%0 and + 8.7%0. These data support a felsic magmatic source for sulphur in the ores, consistent with their proximal position in relation to the porphyries. However, a minor contribution of sulphur from diagenetic pyrite in the host Candelaria sediments (mean &34S = -14.0%o) cannot be ruled out. Sulphur in late, localised barite veins (6345 = + 17.3%o and + 17.7%o) probably originated from a sedimentary/seawater source, in the form of bedded barite within the Palmetto basement (634S = + 18.9%o). Quartz veins from the ores have mean 6~SO = + 15.9 + 0.8%0 (la, n = 10), which is consistent, over the best estimate temperature range of the mineralisation (360~ ~ with deposition from xSO-enriched magmatic-hydrothermal fluids (calculated 3180 fluid = + 9.4%0 to + 13.9%o). Such enrichment probably occurred through isotopic exchange with the basement cherts during fluid ascent from a source * Current address: B. Thomson, 31 Nethermains Road, Muchalls, Kincardineshire AB3 2RN, Scotland, UK pluton. Whole rock data for a propylitised porphyry (6~so= + 14.2%o, 6D = -65%o) support a magmatic fluid source. However, 6D results for fluid inclusions from several vein samples (mean = -108 __+ 14%o, la, n = 6) and for other dike and sediment whole rocks (mean = -110 _ 13%o, la, n = 5) reveal the influence of meteoric waters. The timing of meteoric fluid incursion is unresolved, but possibilities include late-mineralisation groundwater flooding during cooling of the Early Jurassic progenitor porphyry system and/or meteoric fluid circulation driven by Late Cretaceous plutonism.

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Candelaria and other left-oblique slip faults of the Candelaria region, Nevada

Cited by 20 publications

References 0 publications

Active faulting in the Walker Lane

Active faulting in the Walker Lane

Geology of a part of the southern Monte Cristo Range, Esmeralda County, Nevada

The Candelaria silver deposit, Nevada ? preliminary sulphur, oxygen and hydrogen isotope geochemistry

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