Research Hydrologist
Volcano Science Center
Email:
speek@usgs.gov
Office Phone:
650-329-4509
ORCID:
0000-0002-9770-6557
Supervisor:
Shaul Hurwitz
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Note: No formal accuracy tests were conducted and these data are disseminated to allow discussion related to methods. Sample Analyses: Samples were processed at both the USGS in Menlo Park, CA, and at UC Berkeley following established methodology for separating organic material from sinter (Howald et al., 2014; Lowenstern et al., 2016; Slagter et al., 2019). First, the exterior surface of each sample was removed using a rock saw, and then any further material was removed if there was any visible algal material in the interior of the sample. Second, samples underwent a series of chemical baths. Samples were crushed and soaked in 30% hydrogen peroxide for 48 hours to remove any remaining modern algae. Once cleaned,...
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Sample Analyses: Thin sections made at UC Berkeley were brought to the USGS, Menlo Park, CA and were coated with 25 nm carbon. Samples were analyzed at the USGS in Menlo Park, CA in a Tescan VEGA3 Scanning Electron Microscope (SEM) equipped with an Oxford 50 mm2 X-MaxN energy dispersive spectrometer. Thin sections were imaged with backscatter electrons. Energy dispersive X-ray spectroscopy (EDS) analyses and images were collected with an accelerating voltage of 15 kV and a working distance of 15 mm. Database Contents: The data files for “Energy Dispersive X-ray Spectroscopy (EDS) Data” contain representative element spectra analyses of samples UGB-TD-28, -30, -31, -32, -33, -36.
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To characterize eruption activity of the iconic Old Faithful Geyser in Yellowstone National Park over past centuries, we obtained 41 new radiocarbon dates of mineralized wood preserved in the mound of silica that precipitated from erupted waters. Trees do not grow on active geyser mounds, implying that trees grew on the Old Faithful Geyser mound during a protracted period of eruption quiescence. Rooted stumps and root crowns located on higher parts of the mound are evidence that at the time of tree growth, the geyser mound closely resembled its current appearance. The range of calibrated radiocarbon dates (1233–1362 CE) is coincident with a series of severe multidecadal regional droughts toward the end of the Medieval...
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Sulphur Banks, near the summit of Kīlauea Volcano on the Island of Hawai`i, is a thermal area where volcanic gases and steam are discharged. A research well drilled in the 1920s at Sulphur Banks (Allen, 1922) has developed into a “fumarole” that has been used for gas sampling over the years (e.g., Friedman and Reimer, 1987; Hilton and McMurtry, 1997; Shinohara and others, 1999), but has not been subject to periodic monitoring. Following the 2018 Kilauea eruption, draining of the lava lake, and cessation of activity at the summit (Neal and others, 2019), Sulphur Banks represents a continuing window into the outgassing dynamics at Kīlauea’s summit. Gas samples were collected at Sulphur Banks periodically since March...
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This data set consists of chemical and stable isotope data obtained through the analysis of discrete water samples collected from 14 fixed sampling locations in the northern Sacramento-San Joaquin Delta at roughly monthly intervals between April 2011 and November 2012.
Categories: Data;
Tags: Cache Slough,
Lindsey Slough,
Miner Slough,
Prospect Slough,
Sacramento River, All tags...
Sacramento San Joaquin Delta,
Steamboat Slough,
Toe Drain,
USGS Science Data Catalog (SDC),
biogeochemical cycling,
datasets,
light stable isotope analysis,
nutrient content (water),
water quality, Fewer tags
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