Constraints on the history and topography of the Northeastern Sierra Nevada from a Neogene sedimentary basin in the Reno-Verdi area, Western Nevada

Trexler, James H.; Cashman, Patricia H.

doi:10.1130/ges00735.1

Cited by 10 publications

(15 citation statements)

References 35 publications

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“…Neogene sedimentary rocks at Boca reservoir and the Verdi-Mogul area west of Reno ( Fig. 1) record lacustrine conditions as recently as 3 Ma, and have subsequently been tilted and faulted (Trexler et al, 2000;Henry and Perkins, 2001;Mass, 2005;Mass et al, 2009;Trexler et al, 2012). Rapid rates of modern uplift are also indicated by geodetic data.…”

Section: Sierra Frontal Fault Systemmentioning

confidence: 93%

“…First described as part of the Truckee Formation by the 40th Parallel Survey (King, 1878), these rocks were subsequently studied in more detail (Campbell, 1908;Bingler, 1965;Trexler et al, 2000), culminating in a detailed internal stratigraphy and paleogeographic interpretation, paraphrased below, by Trexler et al (2012). There is no evidence of a major topographic barrier to the west when these rocks were deposited, although the modern Sierra Nevada forms a topographic barrier there today.…”

Section: Sierra Frontal Fault Systemmentioning

confidence: 97%

“…Geologic map, Verdi quadrangle, Nevada Bureau of Mines and Geology Map 4Gg. Bonham, H. F., Jr. and Rogers, D. K. (1983) on November 15, 2012 geosphere.gsapubs.org Downloaded from BACKGROUND As reviewed in Trexler et al (2012), the present consensus is that the ancestral Sierra Nevada was high by Eocene time, and sloped down toward the San Joaquin seaway to the west (e.g., Cecil et al, 2004Cecil et al, , 2006Cecil et al, , 2010Mulch et al, 2006). An emerging consensus is that interior Nevada, to the east, was a high plateau, the "Nevadaplano" of Decelles (2004) (e.g., Ernst, 2009, andreferences therein), and that Oligocene tuffs with sources in central Nevada fl owed west beyond the present Sierran divide through paleovalleys (e.g., Faulds et al, 2005b;Garside et al, 2005;Busby et al, 2008;Colgan and Henry, 2009;Hinz et al, 2009).…”

Section: Basin and Rangementioning

confidence: 99%

“…No datable material has been found in the Gravel of Reno, due to the diffi culty of dating coarse, oxidized fl uvial sediments and to the limited exposure of the unit. New ages of 2.61 Ma within the upper Sandstone of Hunter Creek (Trexler et al, 2012) provide the best age constraint. They are consistent with the previous estimates, and confi rm that the Gravel of Reno is <2.61 Ma and is therefore Quaternary (Pleistocene) in age.…”

Section: Sierra Frontal Fault Systemmentioning

confidence: 99%

“…Both the Sierran frontal fault system and the Walker Lane step west into the Sierra Nevada in this general area; the record in the sedimentary section constrains the location, structural style, and timing of both. Strata of the Neogene Verdi basin (~11 are tilted and exposed (Trexler et al, 2012, and references cited therein). Subsequent deposits, the Gravel of Reno and younger glacial-outwash terraces, are also exposed in the Truckee River corridor.…”

Section: Introductionmentioning

confidence: 98%

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Post–2.6 Ma tectonic and topographic evolution of the northeastern Sierra Nevada: The record in the Reno and Verdi basins

Cashman¹,

Trexler²,

Widmer³

et al. 2012

Geosphere

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A coarse conglomerate, known as "the Gravel of Reno," fi lls a deep channel incised into a 2.6 Ma sedimentary section a few km west of Reno, Nevada. The canyon and its conglomerate fi ll record an abrupt shift in both provenance and paleocurrent direction compared with the underlying lake-marginal Neogene strata. Notably, the intermediate volcanic provenance of the Neogene section is supplemented in the overlying conglomerate by large plutonic clasts derived from the Sierran batholith. The syntectonic Gravel of Reno signals the initiation of Pleistocene faulting along the eastern edge of the Sierra Nevada near latitude 40° N.Structures within the Neogene and Quaternary rocks reveal the progressive deformation of the Sierra Nevada's eastern margin. There is no discordance between the basal Gravel of Reno conglomerate and the underlying Neogene sedimentary section, and both are presently tilted 23° east. Therefore, signifi cant tilting did not occur until after channel incision and deposition of the basal conglomerate. The dip within the Gravel of Reno decreases with stratigraphic height, documenting ongoing tilting during deposition. Several pervasive fault sets cut the Neogene rocks; one set of normal faults probably predates much of the tilting, but strike-slip faults appear to have been active synchronously with it. Fault sets include early west-and northwest-dipping normal faults, and two mutually cross-cutting sets of strike-slip faults: northwest-striking dextral faults and northeast-striking sinistral faults. The most continuous mappable fault surfaces, with probably much of the most recent movement, are north-striking faults with normal or oblique-slip motion. Overall, these faults accommodate east-west extension. In summary, the structural style at the northern termination of the Carson Range is characterized by distributed slip along many minor faults, and faulting was synchronous with tilting of the sedimentary section.Gravity studies constrain the location and geometry of the main structures as they pro ject eastward under the Reno basin. A negative anomaly extends eastward from the east-tilted Gravel of Reno. This gravity low (and the Gravel of Reno it represents) terminates eastward against a steep, northstriking gravity gradient under central Reno; we interpret this to mark a west-dipping normal fault, the "Virginia Street fault," which was active throughout deposition of the coarse clastic section. A more localized and pronounced gravity low in west Reno corresponds to the eastward projection of the eastdipping Neogene diatomite that is exposed at the ground surface. The abrupt termination of this negative gravity anomaly requires that the diatomite terminates eastward at depth, therefore documenting the eastern margin of the Neogene lacustrine environment. Other gravity anomalies document both the relief on the sub-Neogene unconformity and a complex pattern of faults that offset Neogene and younger rocks in the Reno basin, consistent with the multiple fault sets seen in outcrop west of Reno.

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