Time-domain electromagnetic surveys at Fort Irwin, San Bernardino County, California, 2010–12

Burgess, Matt; Bedrosian, Paul A.

doi:10.3133/ofr20131024f

Cited by 1 publication

(18 citation statements)

References 4 publications

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“…15) with core recovery of 80, 24, and 43 percent (respectively). Near borehole NELT3, there are two TEM soundings; NL20 is 155 m south of the borehole, and NL11 is 134 m north of the borehole (Burgess and Bedrosian, 2014).…”

Section: Borehole Conditions Sample Collection and Sample Processingmentioning

confidence: 99%

“…Near borehole NELT3, there are two time-domain electromagnetic (TEM) soundings where there is a sharp decrease in minimum-layer model resistivity at 90 ft in NL11 and at 116 ft in NL20 (Burgess and Bedrosian, 2014). Part of the difference in depths to the decrease in resistivity values is likely because of the distance between the sounding, the shallow slope of the lithostratigraphic units, and NL11 is on the north side of a fault (Burgess and Bedrosian, 2014;Miller and others, 2014). Burgess and Bedrosian (2014) equate the sharp decrease in resistivity in these soundings to their pick of a sharp decrease in borehole resistivity at a depth of 105 ft.…”

Section: Interpretations For Stratigraphy In Nelt3mentioning

confidence: 99%

“…Part of the difference in depths to the decrease in resistivity values is likely because of the distance between the sounding, the shallow slope of the lithostratigraphic units, and NL11 is on the north side of a fault (Burgess and Bedrosian, 2014;Miller and others, 2014). Burgess and Bedrosian (2014) equate the sharp decrease in resistivity in these soundings to their pick of a sharp decrease in borehole resistivity at a depth of 105 ft. In several samples from 110 to 800 ft, most cuttings are fragments or clasts of crystallized lava flows, and there are a few fragments of tuffaceous and lithic-rich sedimentary rocks; however, all these cuttings are from parts of Miocene(?)…”

Section: Interpretations For Stratigraphy In Nelt3mentioning

confidence: 99%

“…Near borehole NELT1, there are two TEM soundings, NL3 and NL7. NL3 is 733 m west of the borehole, and NL7 is 2.1 km east of the borehole (Burgess and Bedrosian, 2014; fig. 2).…”

Section: Correlations Of Lithostratigraphic Features To Geophysical Dmentioning

confidence: 99%

“…2). The minimum-layer modeling of NL14 data results in a 5-layer model with a (1) moderate decrease in resistivity at 33 ft, (2) moderate increase at 85 ft, (3) moderate decrease at 164 ft, and (4) small increase at 308 ft (values converted from the original model depths of 10, 26, 50, and 94 m (respectively); Burgess and Bedrosian, 2014). The depths to changes in resistivity values between the borehole and NL14 can differ because of (1) changes in thickness of lithostratigraphic units (and their properties), (2) the dip of lithostratigraphic units, and 3possible separation across a fault (although no fault has been mapped between the borehole and NL14).…”

Section: Correlations Of Lithostratigraphic Features To Geophysical Dmentioning

confidence: 99%

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Lithostratigraphic framework in boreholes from Goldstone Lake and Nelson Lake Basins, Fort Irwin, California

Buesch¹

2018

Open-File Report

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In and 2012, the sedimentary basins in the Fort Irwin National Training Center, California, were evaluated for groundwater resources using a variety of techniques, including drilling of boreholes. This study summarizes lithostratigraphic features and deposits in 8 of 10 boreholes drilled in 2 basins located in the western part of Fort Irwin. The western part of Fort Irwin straddles the eastern edge of the Miocene Eagle Crags volcanic field; therefore, many of the rocks penetrated in the boreholes are primary volcanic deposits (lava flow, pyroclastic flow, and fallout tephra deposits) and tuffaceous or lithic-rich sedimentary rocks (siltstone to cobble conglomerates) deposited in alluvial, fluvial, lacustrine, and possibly groundwater discharge environments. Boreholes were drilled with mud-rotary techniques that result in cuttings samples, and only two to four cores ranging in length from 3 to 5 feet (ft) were collected in each borehole. Of the boreholes studied, maximum depths range from 684 to 903 ft. Borehole GOLD1 penetrated tuffaceous and lithic-rich sandstone, partially welded tuff, avalanche breccia, and basalt lava flows. In addition to cuttings fragments of these rocks, coatings (typically finegrained or smaller sandstone or tuff) attached to clasts can be used to approximate the type of matrix in the drilled rock. Boreholes NELT1 to NELT7, located in Nelson Lake basin, have cuttings fragments of mostly crystallized volcanic lithic clasts with minor amounts of tuff and granitic clasts. Similar to borehole GOLD1, coatings on lithic clasts are used to infer the lithicrich or tuffaceous matrix of the drilled deposits. Most rocks in these boreholes are sandstone to conglomerate that disaggregated (or were broken) during drilling. Correlation of lithostratigraphic features to borehole geophysical logs (especially gamma and resistivity) helps to establish properties of the rock and enables identification of depositional sequences of similar rock types. Lithostratigraphic features and resistivity in boreholes compare reasonably well to nearby time-domain electromagnetic sounding (resistivity) model results. There is no direct age control on the rocks penetrated in the boreholes. The abundance of tuffaceous material as primary or slightly redeposited matrix is used to identify rocks deposited during the activity of the Eagle Crags volcanic field in the Miocene. In contrast, sedimentary rocks composed of detrital and epiclastic grains (only a few of which are tuffaceous rocks as clasts) are inferred to have been deposited during the Quaternary or Pliocene(?). The lithostratigraphic-based estimates of relative age indicate the typical thickness of the Quaternary or Pliocene(?) deposits is 70-170 ft, and that several water-bearing horizons are probable in the Miocene(?) section.

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Section: Borehole Conditions Sample Collection and Sample Processingmentioning

confidence: 99%

Section: Interpretations For Stratigraphy In Nelt3mentioning

confidence: 99%

Section: Interpretations For Stratigraphy In Nelt3mentioning

confidence: 99%

“…Near borehole NELT1, there are two TEM soundings, NL3 and NL7. NL3 is 733 m west of the borehole, and NL7 is 2.1 km east of the borehole (Burgess and Bedrosian, 2014; fig. 2).…”

Section: Correlations Of Lithostratigraphic Features To Geophysical Dmentioning

confidence: 99%

Section: Correlations Of Lithostratigraphic Features To Geophysical Dmentioning

confidence: 99%

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Time-domain electromagnetic surveys at Fort Irwin, San Bernardino County, California, 2010–12

Cited by 1 publication

References 4 publications

Lithostratigraphic framework in boreholes from Goldstone Lake and Nelson Lake Basins, Fort Irwin, California

Lithostratigraphic framework in boreholes from Goldstone Lake and Nelson Lake Basins, Fort Irwin, California

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