Timing, extent, and spatial progression of Neogene displacement transfer, southern Walker Lane, western Great Basin. Development of extensional systems in regions of hot, thick crust: Low-temperature thermochronological and neotectonic constraints from the Middle Magdalena Valley, Llanos basin, and Eastern Cordillera of Colombia Phase 3. Low-temperature thermochronological and neotectonic constraints from the Middle Magdalena Valley, Llanos basin, and Eastern Cordillera of Colombia Phase 2. Low-temperature thermochronological and neotectonic constraints from the Middle Magdalena Valley, Llanos basin, and Eastern Cordillera of Colombia Phase 1. Exhumation of the Colorado Plateau–spatial and temporal distribution and implications for landscape evolution.
Climate Change/Paleoclimate & Geochronology
For example, detrital zircon U-Pb DZ geochronology can be applied to derive maximum depositional age, reconstruct sediment provenance and routing systems, correlate isolated stratigraphic horizons, and characterize remote source terrane geology. While each of these methods in isolation are very valuable tools, they do have some limitations.
For example, DZ geochronology cannot differentiate different sources with the same crystallization age, the youngest DZ age population may be older than depositional age, large orogenic or metamorphic episodes may not produce much primary zircon, and recycling of zircon grains can lead to incorrect interpretation of syn-depositional versus primary sediment source. Detrital LT thermochronology has additional problems such as syn-depositional age volcanic grains leading to erroneous lag-time interpretation.
The principal relative dating methods from stellar evolution are reviewed and a new one, named ΔV, is presented. This new parameter, based on the difference in magnitude between the Horizontal Branch and a point on the main sequence, is particularly robust and largely independent from the cluster metallicity (the only residual theoretical uncertainty being the slope ΔMV(HB)/Δ[Fe/H], i.e.
I took an undergraduate degree in Earth Sciences before earning my Ph. My research interests have included development of techniques in geochronology, with a focus on noble-gas methods and thermochronology and their application to tectonics. I’m also interested in crustal geodynamics, the nature and origin of mountains, and the geologic evolution of Asia, where I’ve worked for 30 years!
I’ve served on the editorial board of the journal Geology, am currently on the advisory board of the journal Earth and Planetary Science Letters, and I’ve served as a panel member for the Continental Dynamics program of the U. I’m thrilled and honored to have been named a Fellow of the American Geophysical Union in and to have received the Dodson prize in thermochronology in Currently I’m Chair of the International Standing Committee on Thermochronology, which oversees the continuity and planning for international workshops every two years.
At Lehigh, I’ve served as department chair from and to I teach graduate courses in tectonic processes and in geochronology, and undergraduate courses on the topics of environmental issues and energy. I’ve also taught first-year seminars on such topics as energy, disaster movies, Himalayan exploration, and environmental change.
We analyzed grains extracted from 35 hand specimens collected from weathering profiles at 11 sites located at 3 distinct elevations. The highest elevation profile hosts the oldest supergene minerals, whereas progressively younger samples occur at lower positions in the landscape. The highest elevation sampling sites three sites , located on top of an elongated mesa to m elevation , yield ages in the 16 to 12 Ma range. Samples from an intermediate elevation site to m elevation yield ages in the 6 to 4 Ma range.
Samples collected at the lowest elevation sites to m elevation yield ages in the 2.
Weathering geochronology by (U-Th)/He dating of goethite evolution during the incremental heating experiments shows that the high retentivity domain has retained chemical-physical erosion, providing insight into landscape evolution and global geochemical cycles.
LaserChron Center U-Th-Pb geochronology has become a fundamental tool in Earth Science research, with applications that cover the span of structural geology, tectonics, stratigraphy, paleontology, petrology, and geochemistry. Although many U-Th-Pb analytical techniques and applications are well established, emerging technologies are revolutionizing the way geochronologic information can be acquired and applied.
Some of the most exciting advances in the field are being driven by laser-ablation multicollector ICP mass spectrometers, which allow for rapid determination of U-Th-Pb ages with micron-scale spatial resolution. These instruments are fundamentally changing the way geochronologic information is utilized in Earth Science research. Accelerator Mass Spectrometry Laboratory After Willard Libby demonstrated in that the time since the death of an object could be determined by measuring its 14C activity, researchers in disciplines from Anthropology to Zoology have exploited this discovery.
Among these researchers are members of the University of Arizona, Department of Geosciences, who for years have studies the 14C content of various anthropological and geophysical specimens. Environmental Isotope Laboratory Faculty, staff, and students in the Environmental Isotope Laboratory employ naturally occurring stable and radioactive isotopes as well as major element compositions to hydrological and geological questions.
Study areas are generally local or in nearby hydrologic basins, and problems range from locations and extent of groundwater recharge to sources of chloride in brines.
Undergraduate and graduate students are involved in most projects. Allan Ashworth’s primary research interests are in paleontology and stratigraphy. He is currently working on the paleoecology of a terrestrial fossil assemblage from the late Tertiary Sirius Group in the Transantarctic Mountains, about km from the South Pole.
To establish the chronology of formation of these terraces, two different dating methods were used on alluvial terraces: exposure age dating using in situ produced cosmogenic 10 Be and luminescence dating. Quaternary, Quaternary geochronology, Landscape Evolution, and 2 more Age Determination and Early Holocene. Bookmark. From transpression.
Knickpoints as geomorphic markers of active tectonics: Uplift of central Mongolia recorded in vesicular basalts. Journal of Geology, , , DOI: Evolution of continental-scale drainage in response to mantle dynamics and surface processes: An example from the Ethiopian Highlands: The dynamic reference frame of rivers and apparent transience in incision rates: Geomorphology, active tectonics, and landscape evolution in the mid-Atlantic region, in Brezinski, D.
Of these, the latter three methods have yet to reach maturity and further work isrequired to fully test their applications to regolith materials; the other methods may be considered tobe? Below I outline some of the highlights of the Geochronology Project and its forerunner, thePaleomagnetic Dating Project. Overviews of Australian regolith geochronology are given in Pillans , Sampling was undertaken in open pit mines, which provided excellent, deep exposures.
Initially it washoped to be able to date the widespread, so called? On the other hand, oxidized saprolite, up to m below thesurface, turned out to be an ideal medium, and revealed a long history of weathering dating back, insome instances, to pre-Cenozoic times.
Interests: Noble gas geochemistry, thermochronometry, and cosmogenic nuclide observations applied to problems involving alpine glacial erosion, chemical weathering, lunar impacts and magnetism, and thermal conditions of Martian meteorites.
The flood of Januruy 8, is the largest flood preserved in the paleoflood record for Tonto Creek, and probably was the largest flood in the past three hundred years on Tonto Creek. Deposits left by the flood provided an opportunity to calibrate the results of the previous paleoflood analysis of Tonto Creek completed by O’Connor and others, In addition, these deposits afforded a rare opportunity to test some of the basic assumptions of the paleoflood methodology, which has been applied on a variety of streams throughout the world.
Hydraulic modeling of the largest flood indicates that a peak discharge of about cubic meters per second cms 50, cfs occurred on Tonto Creek at the study reach. Comparison of peak discharge estimates based on various of types of flood deposits left by floods indicates that peak discharge estimates based on slackwater sediment elevations alone underestimate maximum flood peaks by about 30 percent relative to peak discharge estimates based on flotsam elevations House and others, The year paleoflood record preserved in the study reach indicates that the largest peak discharges on Tonto Creek have occurred since , the period of record of the USGS stream gage on Tonto Creek.
Dr David Fink
An introduction to the principles of physical and historical geology. Topics include weathering, erosion, glaciation, volcanism, earthquakes, rocks, minerals, maps, and the origin of the earth and its physical and biological development. Open to all students except those with previous credit in geology, or earth science majors and those nonscience majors who plan an eight-hour sequence in geology.
Postdoctoral researchers are invited to use one or more of the following techniques — fieldwork, geochronology, topographic analysis, geophysics, and/or landscape process models — to address issues related to the record of coseismic landslides in the CSZ region to inform the understanding of frequency, magnitude, and geologic and geographic.
A provenance study of the Paleozoic Ventania System Argentina: These ranges formed as result of the late Paleozoic collision of the Patagonia terrane against the continental margin of Gondwana. The provenance analysis together with the sedimentary paleocurrents confirm a dominant source from the Tandilia System, a Paleoproterozoic mountain belt formed during the amalgamation of the Rio de la Plata Craton at about Ma, and incorporated to Western Gondwana during the Brasiliano Orogeny at Ma.
The local dominant source at the base of the early Paleozoic changed to more distant supplies toward the top of the sequences, when an increasing participation of detritus from first, Cambrian Ma zircons from the Pampean Orogen, and later on Ordovician Ma zircons from the Famatinian Orogen is recorded. The detrital zircon patterns and the maximum age of the units shed light on some previous discrepancies in the early Paleozoic stratigraphy.
The Balcarce Formation, an early Paleozoic sedimentary cover of the Tandilia metamorphic and igneous basement, shows striking differences when compared with the new data from the Ventania System. The two data-sets reveal different sources for the two regions. The late Paleozoic foreland basin deposits mark an abrupt change of degrees in the paleocurrent directions, in the petrographic composition of the sediments, and in the provenance of detrital zircons.
These data indicate a southern provenance with the first evidence of Carboniferous and Permian magmatic zircons. The oldest Archean zircons together with the finding of clasts with archeocyathids support the provenance from Patagonia, which was derived from Eastern Gondwana. The U-Pb data together with the Lu-Hf isotopic data enhance the comprehension of the tectonic evolution of the Ventania System as part of the larger Gondwanides Belt that amalgamated to Western Gondwana during Late Permian times with some independent pieces derived from Eastern Gondwana.
Faculty, Staff and Students
Concordia diagram showing significant U-Pb discorodance in lower crustal rutile. Degree of discordance has been linked to cooling rate through the Pb partial retention zone see Blackburn et al. Xenoliths from multiple depths km record the slow relaxation of the continental crust’s geothermal gradient. U-Series Comminution Dating Recent modeling and isotopic studies have shown promising results for harnessing the use of disequilibria in the U decay chain generated by the physical reduction in particle size and the ejected loss of intermediate daughter products.
Measurement of intermediate daughter products Th, and Ra can be used to test whether physical ejection is occurring, and more importantly can provide the means to accurately model the particle size and thus improve the accuracy of comminution dates. Intercalation with well-dated volcanics note Sherwin Till beneath Bishop tuff, photo makes this an ideal site for testing a new geochronologic tool.
Pebble abrasion is a key factor controlling the release of minerals into sand, but few attempts have been made to model how it could influence the liberation of minerals into the size fraction used in detrital geochronology.
Evolution’s Radiometric Dating Methods: November 27, Creation vs Evolution Add Comment Although many things about a rock can be measured, its age cannot be directly measured. Radiometric dating techniques relies upon assumptions. To help you understand the reality of radiometric dating, think of it like this: So all we have is the height of the candle, and the rate at which it is currently burning.
You still cannot figure out when it was lit, unless you make some assumptions. How tall was the candle to begin with?
Geoscience (GEOS) Courses
Dating caves is problematic, however, because their ages are only constrained by the oldest deposits contained within, which may be far younger than the cave itself. The sampled caves formed sequentially as the water table lowered, providing an important stratigraphic test for the dating methods. Large discrepancies between deposit ages from similar cave levels demonstrate that, even when accurately determined, deposit ages can seriously underestimate the timing of cave development.
Paleomagnetic dating requires correlation with the global reversal chronology, and is hindered by a lack of continuous stratigraphy.
Geoarchaeology, Paleoindian archaeology, soil-geomorphology, and Quaternary landscape evolution and paleoenvironments. Prior to moving to UA, most research was on the Great Plains, but has since focused on the Southwest U.S. and Northwest Mexico.
Techniques, Interpretations, and Applications Peter W. ISBN ; ISBN13 The publication of this volume occurs at the one-hundredth anniversary of , which has been called the annus mirabilus because it was the year of a number of enormous scientific advances. Also of significance in was the first application of another major advance in physics, which dramatically changed the fields of Earth and planetary science.
In March of and published the following year , Ernest Rutherford presented the following in the Silliman Lectures at Yale: If the rate of production of helium from known weights of the different radioelements were experimentally known, it should thus be possible to determine the interval required for the production of the amount of helium observed in radioactive minerals, or, in other words, to determine the age of the mineral. Charles Scriber’s Sons, NY Thus radioisotopic geochronology was born, almost immediately shattering centuries of speculative conjectures and estimates and laying the foundation for establishment of the geologic timescale, the age of the Earth and meteorites, and a quantitative understanding of the rates of processes ranging from nebular condensation to Quaternary glaciations.
There is an important subplot to the historical development of radioisotopic dating over the last hundred years, which, ironically, arises directly from the subsequent history of the U-He dating method Rutherford described in Strutt noted in , He ages only provided “minimum values, because helium leaks out from the mineral, to what extent it is impossible to say” Strutt, , Proc Roy Soc Lond, Ser A In it may have been impossible to say the extent to which He or most other elements leaked out of minerals, but eventually a growing understanding of thermally-activated diffusion and annealing began to shed light on the significance of such ages.