hodges group | integrated earth and space science


It lies south of the Ol Doinyo Eburru complex and north of the Suswa volcano; it is east of the rift valley’s western margin and west of Mount Longonot , a stratovolcano. The complex contains many centers of volcanic activity that often erupt in small volumes. This is thought to be related to a caldera 11 kilometres 6. Although dating is not precise, it seems that the older rocks date to before 9, years before present, while the youngest rocks in the Olobutot formation are between and years old. However the absence of tritium in the steam shows that the water is taking at least fifty years to travel from the lake, if that is indeed the source. Two unsuccessful test wells had been drilled by Thirty production wells had been sunk by of which twenty-seven were productive, each yielding from 1. Following rising power demands, a third station, Olkaria II was built with a production capacity of MW with 5. It is powered by 3 Mitsubishi turbines each capable of generating 35MW.

Professor Fin Stuart

However, this method has rarely been applied to karstified aquifers and in particular to drip water in caves, despite the importance of the information which may be obtained. Besides the determination of transfer times of climate signals from the atmosphere through the epikarst to speleothems as climate archives, 3H—3He together with Ne, Ar, Kr, Xe data may also help to give new insights into the local hydrogeology, e. In order to check the applicability of 3H—3He dating to cave drips, we collected drip water samples from three adjacent caves in northwestern Germany during several campaigns.

The noble gas data were evaluated by inverse modelling to obtain recharge temperature and excess air, supporting the calculation of the tritiogenic 3He and hence the 3H—3He age.

Recent advances in dating young groundwater: chlorofluorocarbons, 3W3He and *‘Kr P.G. Cookas*, D.K. Solomonb 3H/3He ratio in groundwater are three techniques that have become available within recent mination of both 3H and tritiogenic 3He (3He*) can be used as a dating tool (Tolstikhin and Kamensky, ). The 3W3He age is defined as.

I am interested in natural landscapes and the geologic processes responsible for their formation. My research has focused on the following topics see references: Pleistocene glaciations of the Rocky Mountains and adjacent areas. Yellowstone caldera unrest The track of the Yellowstone hotspot: Volcanism, faulting and uplift Quaternary faulting and neotectonics Geologic controls on ecology of the greater Yellowstone area Committee Participation I have appreciated serving on the following student committees, and as of December , I am on about 4 additional graduate student thesis committees.

Quaternary Science REviews 27, p. Geological Society of America Field Guide 10, p. Geological Survey Professional Paper , p. The roles of mantle plumes and the lithospere, in I.

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For separation of terrigenic helium, trjtium have to use neon measurements. This component can be radiogenic helium, mantle helium, or a mixture of these two components. Check out our recipe of the month from Jersey Fresh: After oxidation to HTO, it takes part in the natural water cycle.

Our research, which uses cosmogenic 3He dating rather than K-Ar dating of rocks, shows that the Toroweap fault has been moving at the same rate for at least the past , years (Fenton et al., ), and because the offsets in the Toroweap and Prospect lava dams were essentially the same, that the ages of the lava flows should be the same as.

The goals of this project were to provide age constraints for Antarctic glacial events, to investigate production mechanisms of 3He, lOBe, and 26 A1 in terrestrial rocks, to constrain the importance of loss of 3He from quartz due to diffusion, and to refine methods of exposure-age dating. Comparison of measured lOBe concentrations in Sirius Group deposits with those predicted with a model of the effects of uplift on 10Be production suggests minimal uplift of the Transantarctic Mountains over the last 3 myr.

The age range suggests that this deposit does not, as previous studies suggested, represent a single ice advance in response to lowered sea level at the last glacial maximum. The age range may reflect several ice sheet advances during the last glacial period. Paired measurements of 3He and 10Be in a number of quartz sandstones from the Dry Valleys region show that cosmogenic 3He is not completely retained on time scales of greater than kyr.

These values are one to three orders of magnitude greater than previous experimental determinations extrapolated to low temperature.

Antarctic glacial chronology : new constraints from surface exposure dating

Apparatus used for filtration of dust particles from an ice core sample in order to measure extraterrestrial helium. Polar ice provides an archive of the IDP flux. Cosmic dust flux estimates from 3He in ice cores agree well with other independent estimates. Polar ice is especially advantageous in this research because accumulation rates in ice cores are well known, there is very little terrestrial dust relative to other archives such as ocean sediments, 3He is dominated by the extraterrestrial source, chronologies are well established, and samples on a variety of time scales are available.

Polar ice samples from ablation regions where large amounts of material can be obtained may become especially important for studies of extraterrestrial dust.

– Ph.D at CEREGE – Université Paul Cézanne (Aix Marseille III) Les isotopes cosmogéniques 3He et 10Be dans les minéraux mafiques: développements analytiques, calibration et nouvelles applications.

If both the tritium and 3 He trit concentrations are measured in TU. Groundwater age dating tritium LLNL has developed a noble gas mass spectrometry facility that houses a state-of-the-art water-gas separation manifold and mass spectrometry system groundwater age dating tritium specifically for high throughput of groundwater samples. The Dissolved and Noble Gas Lab primarily carries groundwater age dating tritium groundwater age dating by measuring the concentrations of helium-3 3 Hea rare stable isotope, and tritium 3 Ha radioactive isotope of hydrogen.

This system represents a capability for characterizing groundwater recharge conditions by dissolved gas analysis that is unmatched by any other laboratory. Background The increasing national and international demand for water has led to increasing reliance on subsurface storage, both for naturally and artificially recharged water. Rock Dating and Groundwater age dating tritium The measurement of cosmogenic helium makes it possible to date rocks.

The most practical approach to determining R terr is to measure it in groundwater samples from the same aquifer that are free of tritium.

Welcome to the George Hotel Cranbrook

I am an isotope geochemist with research interests that include: The differentiation history of planet Earth, and the generation of the atmosphere. Tracing the source and the interaction history of modern and ancient fluids in the Earth crust. Using cosmogenic isotopes to determine the controls of long-term landscape change.

Using low temperature thermochronometers for constraining the tectonic history of the shallow crust. I frequently collaborate with scientists in the fields of petrology, geomorphology, mineralization and tectonics.

Search in Geochemistry, Geophysics, Geosystems Search Search Clear search. Advertisement between 65 and 14ka constrained by cosmogenic 3He dating, Quaternary Research, , 82, 1, CrossRef; An alternative isochron method for measuring cosmogenic 3He in lava flows, Chemical Geology, ,

This wide exceeding 1. Toreva blocks are best developed along the eastern side of the river — they exhibit coherently-dipping, patinated tops that can be reconstructed to the gorge walls, but with toes that are truncated or buried by later deposits. Located below these landslide features is a flight of fill and fill-cut terraces spanning 6 levels at elevations of 60, 45, 29, 25, 15 and 7 m above the modern river grade, on average. Terraces at 29 m can be correlated across and along the river axis, whereas others are more locally preserved.

All terraces exhibit well-defined boulder levees and risers constructed from alluvium sourced from upstream, and rounded and sculpted basalt clasts on their treads. Minimum 3He surface exposure ages of multiple samples from each terrace indicate Qt6 was likely abandoned at This incision was likely coincident with toreva block formation and substantial gorge widening, as the toreva blocks and large-scale incohesive landslide deposits predate terrace development.

Landsliding controls the width of the gorge along this stretch, leading to a These landsliding events were likely primarily driven by undercutting of basaltic bedrock along weaker gravel horizons. Gorge narrowing is observed during this time period, with only minor widening accommodated by slumping and incoherent landsliding that post-date terrace treads.

These increasingly rapid incision rates mirror the phenomena seen in other western US river systems since the Pliocene.

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Geochronology of the Carrizozo Malpais We are a research and service division of: The apparently-young Carrizozo lava flows have proven very difficult to date. No carbon suitable for C analysis has been found under the Carrizozo flows. Allen estimated, based on visual observation, that the flows are less than years old, and Weber estimated the age as yrs old. These ages may have been influenced by age estimates for the geomorphically-similar and nearby McCarty’s lava flow that was estimated to have erupted roughly yrs ago, based on Acoma Indian legend, and an apparent stratigraphic relationship with Pueblo I artifacts Nichols et al.

Since then, Salyards estimated an age of approximately yrs, based on secular variation magnetostratigraphy.

Sample dating costs were provided by PI’s ongoing RCAP grants. Graduate student Nathaniel Blackburn conducted this part and completed his MS thesis in spring 3) Undergraduate student Helen Flynn travelled to Ethiopia in summer to collect data as part of this project.

Glaciers Abstract Surface exposure dating, using the concentration of cosmogenic nuclides 3He, 21Ne, and 36Cl in moraine boulders, combined with mapping of glacial moraines from three key locations, is used to provide new constraints to Antarctic glacial chronology. Paired 3He and 36Cl measurements are consistent with negligible surface erosion which is inferred from flow morphology.

These mid-latitude, long term, 3He production rates reduce uncertainties previously introduced when scaling production rates calibrated at lower latitudes to Antarctica. The results also confirm the compositional dependence of 3He production rates predicted by theoretical calculations and are used to scale the production rates to quartz. For exposures longer than about 30, years the inherited component can be ignored. These results enable correction for inherited 3He in less than 30, year exposures of these common Antarctic lithologies.

Exposure ages of less than years were obtained on moraine boulders in the Dominion Range. Waesche, a moraine band on the flank of the volcano records past ice elevations up to 85 meters above the present ice elevation. This conclusion is supported by results from a time-dependent ice sheet model. Surface exposure ages from the upper part of the moraine band are scattered ka , but consistently fall within glacial low sea level stages in the marine isotope record, including an interstadial during the last interglacial stage.

Paired 3He and 36CI data are consistent with negligible erosion. The exposure ages on the older Beardmore 2 drift are more scattered ka. The Meyer drift records at least four expansions of the upper Beardmore Glacier. Because Meyer drift geometry is similar to that of the Beardmore drift, these drifts also likely record an expanded WAIS.


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