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Full-Text Articles in Physical Sciences and Mathematics
Decoupling Of Erosion And Precipitation In The Himalayas, D Burbank, Ann Blythe, J Putkonen, B Pratt-Sitaula, E Gabet, M Oskin, A Barros, T Ohja
Decoupling Of Erosion And Precipitation In The Himalayas, D Burbank, Ann Blythe, J Putkonen, B Pratt-Sitaula, E Gabet, M Oskin, A Barros, T Ohja
Ann Blythe
The hypothesis that abrupt spatial gradients in erosion can cause high strain rates in active orogens has been supported by numerical models that couple erosional processes with lithospheric deformation via gravitational feedbacks1, 2, 3. Most such models invoke a 'stream-power' rule, in which either increased discharge or steeper channel slopes cause higher erosion rates. Spatial variations in precipitation and slopes are therefore predicted to correlate with gradients in both erosion rates and crustal strain. Here we combine observations from a meteorological network across the Greater Himalaya, Nepal, along with estimates of erosion rates at geologic timescales (greater than 100,000 yr) …
Using Information Literacy Standards To Improve Geoscience Courses, Aimee Dechambeau, Ira Sasowsky
Using Information Literacy Standards To Improve Geoscience Courses, Aimee Dechambeau, Ira Sasowsky
Aimee deChambeau
Information literacy (IL) is the set of skills that enables a person to find, evaluate, and use information. Although IL is important in the geosciences, it is hard to teach because the information comes in so many forms. Most geoscience courses include work that implicitly addresses some IL issues. However, because of the importance of IL, it is worthwhile to explicitly include it as part of the curriculum. The Association of College and Research Libraries has developed Information Literacy Standards for Higher Education that may be used to assess an individual's level of information literacy. We introduce a method for …
Implications Of Distributed Crustal Deformation For Exhumation In A Portion Of A Transpressional Plate Boundary, Western Transverse Ranges, Southern California, Andrew Meigs, Dong Yule, Ann Blythe, Doug Burbank
Implications Of Distributed Crustal Deformation For Exhumation In A Portion Of A Transpressional Plate Boundary, Western Transverse Ranges, Southern California, Andrew Meigs, Dong Yule, Ann Blythe, Doug Burbank
Ann Blythe
Spatial and temporal patterns of exhumation are inextricably linked to patterns of crustal deformation because crustal deformation drives rock uplift. A new interpretation of a segment of the Pacific-North America transpressional plate boundary in southern California is analyzed in the context of crustal shortening, rock uplift, and exhumation. Deformation is partitioned between two structural anticlinoria formed above thrust faults that root into a mid-crustal décollement. The southern anticlinorium began growing after 5 Ma and is characterized by almost no topographic expression, rock uplift of ∼3 km, and exhumation of <1.2 km. Deposition in the Los Angeles basin on the south generally kept pace with growth of this anticlinorium. In contrast, the northern anticlinorium is younger, has a significant topographic expression, rock uplift of 2.5–4.0 km, and exhumation of ∼1.5–2 km. On-going surface uplift above the northern anticlinorium is suggested by the mismatch between the magnitude of rock uplift relative to the exhumation. These data emphasize that the distribution of deformation between faults in the upper and middle crust, crustal root formation in the lower crust, and flexural subsidence are primary controls of patterns of exhumation, which together dictate net surface uplift in active orogenic belts.
Geochemistry Of Kauai Shield-Stage Lavas: Implications For The Chemical Evolution Of The Hawaiian Plume, Scott Bogue, S. Mukhopadhyay, J.C. Lassiter, K.A. Farley
Geochemistry Of Kauai Shield-Stage Lavas: Implications For The Chemical Evolution Of The Hawaiian Plume, Scott Bogue, S. Mukhopadhyay, J.C. Lassiter, K.A. Farley
Scott Bogue
We measured He, Sr, Nd, Pb, and Os isotope ratios and major and trace element concentrations in stratigraphically and paleomagnetically controlled shield-stage lavas from Kauai, Hawaii. The range of 3He/4He ratios (17–28 RA) from Kauai is similar to that reported from Loihi and thus challenges the prevailing notion that high 3He/4He ratios are restricted to the preshield stage of Hawaiian magmatism. 3He/4He ratios vary erratically with stratigraphic position, and chronostratigraphic control from paleomagnetic data indicates very rapid changes in the 3He/4He ratios (up to 8 RA in ∼102 years). These variations in helium isotopic ratios are correlated with variations in …
No Frictional Heat Along The San Gabriel Fault, California: Evidence From Fission-Track Thermochronology, M.A. D’Alessio, Ann Blythe, R Bu¨Rgmann
No Frictional Heat Along The San Gabriel Fault, California: Evidence From Fission-Track Thermochronology, M.A. D’Alessio, Ann Blythe, R Bu¨Rgmann
Ann Blythe
Large earthquakes generate frictional heat, and the magnitude of heating is related to the slip magnitude, the applied effective normal stress, and the frictional strength of the fault. We looked for evidence of this heating in apatite fission-track age and track-length distributions of samples from adjacent to and within the San Gabriel fault zone in southern California. The fault is thought to be an abandoned major trace of the San Andreas fault system active from 13 to 4 Ma and has since been exhumed from depths of 2–5 km. At our sample locality, as much as 40 km of total …