These data were collected using field portable (handheld) X-ray fluorescence (pXRF) equipped with a 4-watt Ta/Au X-ray tube. Samples of surficial alluvium, rock, and archived drill cuttings from monitoring wells in the western part of the Mojave Desert, 60 to 210 kilometers (km) northeast of Los Angeles, California, were measured using as part of an investigation of naturally-occurring trace elements dissolved in groundwater. Surficial alluvium samples were collected from small stream channels draining distinct geologic units, or from previously mapped river deposits, and generally consisted of silt, sand, and granules to small pebbles. Twigs and other detritus were removed prior to measurement. Rocks were collected from outcrops or from colluvium eroded from nearby outcrops and were broken to expose fresh surfaces whenever possible. Measurements were made on 180 samples of alluvium and rock, and archived drill material (cuttings) from 24 monitoring well sites, located over an approximately 14,300 square km area between March 2015 and May 2018. Measurements on National Institute of Standards and Technology (NIST) and U.S. Geological Survey standard reference materials (available in a separate child page associated with https://doi.org/10.5066/P9CU0EH3) indicated the pXRF was sufficiently accurate for selected trace elements for the intended purpose of the dataset. Standard reference material indicated a need to adjust instrument beam times to optimize measurements of chromium. Measurements on a silica dioxide blank showed consistent clean (few to no measurable elements) data.

These data were collected using field portable (handheld) X-ray fluorescence (pXRF) equipped with a 4-watt Ta/Au X-ray tube on two National Institute of Standards and Technology (NIST) certified standard reference materials 2710a and 2711a, a U.S. Geological Survey (USGS) certified standard reference material BHVO-2, and a silicon dioxide blank. These quality assurance data were collected as part of detailed pXRF studies in Hinkley and Water Valleys, 140 kilometers (km) northeast of Los Angeles, California, and as part of a regional geochemical survey in the western Mojave Desert, between 60 to 210 km northeast of Los Angeles. Measurements on National Institute of Standards and Technology (NIST) and U.S. Geological Survey standard reference materials indicated the pXRF was sufficiently accurate for the purposes of these studies for chromium and selected trace elements. Results showed consistent clean (few to no measurable elements) measurements on a silica dioxide blank. Standard reference material indicated a need to adjust instrument beam times to optimize measurements of chromium.

These data were collected using field portable (handheld) X-ray fluorescence (pXRF) equipped with a 4-watt Ta/Au X-ray tube. Samples of surficial alluvium, rock, and archived core material from existing auger- or sonic-drilled monitoring wells in Hinkley Valley and the adjoining Water Valley, 140 kilometers (km) northeast of Los Angeles, California, were measured as part of an investigation of naturally-occurring and anthropogenic hexavalent chromium, Cr(VI), concentrations in local groundwater. Surficial alluvium samples were collected from small stream channels draining distinct geologic units, or from previously mapped river deposits, and generally consisted of silt, sand, and granules to small pebbles. Twigs and other detritus were removed prior to measurement. Rocks were collected from outcrops or from colluvium eroded from nearby outcrops and were broken to expose fresh surfaces whenever possible. Core material was measured within the screened interval of wells sampled for water-quality as part of the study, along with additional core material from other intervals of geologic or lithologic interest to the study. Some measurements of core material were made on materials from selected geologic settings including oxide-rich zones formed near lithologic and redox contacts, groundwater discharge deposits, and weathered bedrock. Measurements were made on 155 samples of alluvium and rock, and archived core material from 69 monitoring well sites, located over an approximately 200 square km area between March 2015 and May 2018. Measurements on National Institute of Standards and Technology (NIST) and U.S. Geological Survey standard reference materials (available in a separate child page associated with https://doi.org/10.5066/P9CU0EH3) indicated the pXRF was sufficiently accurate for chromium and selected trace elements for the intended purpose of the dataset. Standard reference material indicated a need to adjust instrument beam times to optimize measurements of chromium. Measurements on a silica dioxide blank showed consistent clean (few to no measurable elements) data.

Heavy and light mineral separates were extracted from the 36 collected field samples following a USGS procedure (Strong and Driscoll, 2016) and analyzed using the handheld portable X-ray fluorescence (pXRF) analyzer as part of a study examining the occurrence of chromium and natural and anthropogenic hexavalent Chromium, Cr(VI), in groundwater. Data will be used to estimate naturally-occurring background Cr(VI) concentrations upgradient, near the plume margins, and downgradient from a mapped Cr(VI) contamination plume near Hinkley, CA (Izbicki and Groover, 2016). These pXRF results are part of a data release including grain size distribution, photographic and associated chemical and mineral analysis data for 36 sediment core and alluvium samples as well as Scanning Electron Microscopy analysis on select grains from magnetic and heavy mineral separates collected near Hinkley, CA. The cooperator for this study is the Lahontan Regional Water Quality Control Board.

Samples were analyzed using the handheld portable X-ray fluorescence (pXRF) analyzer as part of a study examining the occurrence chromium and of natural and anthropogenic hexavalent Chromium, Cr(VI) in groundwater. Data will be used to estimate naturally-occurring background Cr(VI) concentrations upgradient, near the plume margins, and downgradient from a mapped Cr(VI) contamination plume near Hinkley, CA (Izbicki and Groover, 2016). Relative concentrations for 18 elements of interest were measured on the less than 2mm and sized- fraction splits of the 36 field samples. Greater than 20 percent of the samples analyzed using pXRF also have Contract Laboratory results for comparison. These pXRF results are part of a data release including grain size distribution, photographic, and associated chemical and mineral analysis data for 36 sediment core and alluvium samples as well as Scanning Electron Microscopy analyses on select grains from magnetic and heavy mineral separates collected near Hinkley, CA. The cooperator for this study is the Lahontan Regional Water Quality Control Board.

Several historic, multi-fault ruptures in the Eastern California Shear Zone (ECSZ) reinforce the need to understand how this rupture style contributes to seismic hazard in complex and diffuse fault zones. Several historic earthquakes in the ECSZ, the 1992 Landers, the 1999 Hector Mine, and the 2019 Ridgecrest rupture sequence, involved complex and multi-fault rupture. However, paleoseismic evidence of multi-fault ruptures in the ECSZ is poorly resolved in the rock record. Here I investigate paleoseismic evidence for complex rupture in Panamint Valley, located ~50 km northeast of the 2019 Ridgecrest ruptures. Late Holocene scarps in the 10 km-wide transtensional relay between the Ash Hill and Panamint Valley faults display surface rupture geometries analogous to those produced during the 1992 Landers and 1999 Hector Mine earthquakes. I produce a 1:4000 scale tectonogeomorphic map of the 40 km² area between the Ash Hill and Panamint Valley faults using my locally-calibrated relative-age alluvial fan chronology and using NCALM lidar DEMs and aerial imagery to identify ruptures. I bracket earthquakes with post-IR feldspar infrared-stimulated luminescence dating of offset deposits. I record vertical and lateral offsets at over 250+ locations using field mapping and backslipped reconstructions of newly generated high resolution (5 cm) drone-based structure from motion digital surface models. My mapping shows that the transtensional relay consists of 100+ fault strands that occur in parallel and en échelon arrays 5-7 km in length, with spacings of 1s to 100s of meters. Using my relative-age fan stratigraphy, geochronologic dating of offset deposits, and relative cumulative offset, I identify four late Holocene ruptures at ~0.3 – ~0.7 ka, ~0.7 – 2.4 ka, ~2.6 – 3.6 ka, and ~3.6 – 4.2 ka. Displacement magnitude per event ranges from 0.6 – 1.0 m of lateral slip and 0 – 0.2 m of dip slip. Displacement-length scaling relationships suggest that these mapped faults cannot rupture independently of a larger fault system. My results show overlap in the timing of ruptures in the transtensional relay, on the Ash Hill and Panamint faults, and that the Ash Hill and transtensional relay are kinematically similar. These similarities suggest this region acts as a zone for complex strain transfer between the Ash Hill and Panamint faults over multiple earthquake cycles. These relationships may support a geometric link at depth or the reoccupation of preexisting weaknesses at depth capable of transferring strain over larger distances.

Several historic, multi-fault ruptures in the Eastern California Shear Zone (ECSZ) reinforce the need to understand how this rupture style contributes to seismic hazard in complex and diffuse fault zones. Several historic earthquakes in the ECSZ, the 1992 Landers, the 1999 Hector Mine, and the 2019 Ridgecrest rupture sequence, involved complex and multi-fault rupture. However, paleoseismic evidence of multi-fault ruptures in the ECSZ is poorly resolved in the rock record. Here I investigate paleoseismic evidence for complex rupture in Panamint Valley, located ~50 km northeast of the 2019 Ridgecrest ruptures. Late Holocene scarps in the 10 km-wide transtensional relay between the Ash Hill and Panamint Valley faults display surface rupture geometries analogous to those produced during the 1992 Landers and 1999 Hector Mine earthquakes. I produce a 1:4000 scale tectonogeomorphic map of the 40 km² area between the Ash Hill and Panamint Valley faults using my locally-calibrated relative-age alluvial fan chronology and using NCALM lidar DEMs and aerial imagery to identify ruptures. I bracket earthquakes with post-IR feldspar infrared-stimulated luminescence dating of offset deposits. I record vertical and lateral offsets at over 250+ locations using field mapping and backslipped reconstructions of newly generated high resolution (5 cm) drone-based structure from motion digital surface models. My mapping shows that the transtensional relay consists of 100+ fault strands that occur in parallel and en échelon arrays 5-7 km in length, with spacings of 1s to 100s of meters. Using my relative-age fan stratigraphy, geochronologic dating of offset deposits, and relative cumulative offset, I identify four late Holocene ruptures at ~0.3 – ~0.7 ka, ~0.7 – 2.4 ka, ~2.6 – 3.6 ka, and ~3.6 – 4.2 ka. Displacement magnitude per event ranges from 0.6 – 1.0 m of lateral slip and 0 – 0.2 m of dip slip. Displacement-length scaling relationships suggest that these mapped faults cannot rupture independently of a larger fault system. My results show overlap in the timing of ruptures in the transtensional relay, on the Ash Hill and Panamint faults, and that the Ash Hill and transtensional relay are kinematically similar. These similarities suggest this region acts as a zone for complex strain transfer between the Ash Hill and Panamint faults over multiple earthquake cycles. These relationships may support a geometric link at depth or the reoccupation of preexisting weaknesses at depth capable of transferring strain over larger distances.

This portion of the data release presents X-ray Flourescence (XRF) data from vibracores collected from Searsville Lake, a reservoir in Jasper Ridge Biological Preserve, Stanford, California in October 2018 (USGS Field Activity 2018-682-FA). The XRF data are provided in comma-delimited files (.csv), one per core.

The dataset documents results from portable X-ray fluorescence (pXRF) analysis conducted on a suite of sediment samples from U.S. Army Base Fort Drum, Jefferson County, New York. Most of the pXRF samples were collected from representative cells in a series of five portable optically stimulated luminescence (OSL) grids, here denoted G1 through G5, to constrain variations in elemental abundances within the grids. These samples were also collected in conjunction with OSL for absolute chronology. In the lab, pXRF analysis was conducted using a Bruker S1 Titan instrument housed in the Bascom Laser Diffraction Sedimentology Laboratory at the U.S. Geological Survey in Reston, Virginia. Most of these samples were previously analyzed for particle size, and subsamples from G3 and G4 were also analyzed separately via inductively coupled plasma - mass spectrometry (ICP-MS) to further constrain elemental abundances. This work is a collaboration with the Fort Drum Environmental Division and the Fort Drum Cultural Resources Division and was funded by the National Cooperative Geologic Mapping Program. This Data Release was revised to v1.1 in May 2025 to correct the IDs and coordinates for three samples. No other changes to the data release were made for v1.1.

This data release describes micrometeorological and soil-moisture data collected from January 1, 2017 through May 31, 2019 at the Amargosa Desert Research Site adjacent to a low-level radioactive waste and hazardous chemical waste facility near Beatty, Nevada. Micrometeorological data include precipitation, solar radiation, air temperature, relative humidity, saturated and ambient vapor pressure, wind speed and direction, barometric pressure, and soil-water content. Soil-moisture data include periodic measurements of volumetric water-content at four experimental sites that represent vegetated native soil, devegetated native soil, and two simulated waste disposal trenches—maximum measurement depths range from 5.25 to 29.25 meters. All data are compiled in electronic spreadsheets that are included with this release.