Geology Commons^™

Cretaceous−Cenozoic History Of The Southern Tan-Lu Fault Zone: Apatite Fission-Track And Structural Constraints From The Dabie Shan (Eastern China), J Grimmer, R Jonckheere, E Enkelmann, L Ratschbacher, B Hacker, Ann Blythe, G Wagner, Q Wue, S Liu, S Dong

Ann Blythe

Apatite fission-track (AFT) and structural data outline the Late Cretaceous−Cenozoic history of the southern Tan-Lu fault zone (TLFZ), one of Asia's major faults, the Triassic–Jurassic Dabie orogen, Earth's largest track of ultrahigh-pressure rock exposure, and its foreland, the Yangtze foreland fold-thrust belt. The fission-track analyses utilized the independent (φ-), Z- and ξ-methods for age determination, which yielded within error identical ages. Ages from Triassic–Jurassic syn-orogenic foreland sediments are younger than their depositional age and thus were reset. A group of ages records rapid cooling following shallow emplacement of granitoids of the widespread latest Jurassic−Early Cretaceous “Yanshanian” magmatism. Most ages are …

Controls On The Erosion And Geomorphic Evolution Of The San Bernardino And San Gabriel Mountains, Southern California, J Spotila, M House, Ann Blythe, N Niemi, G Bank

Ann Blythe

No abstract provided.

Low-Temperature Thermochronology Of The San Gabriel And San Bernardino Mountains, Southern California: Constraining Structural Evolution, Ann Blythe, M House, J Spotila

Ann Blythe

No abstract provided.

International Supplement To Graptolite Macroevolution: Phylogenetic Analysis And Testing Hypotheses Of Directional Change, Daniel Goldman

Daniel Goldman

Funding agency: National Science Foundation Amount: $12,058.00 Year: 2002/2 yrs.

An Experimental Study Of Grain Scale Melt Segregation Mechanisms In Two Common Crustal Rock Types, Caleb W. Holyoke Iii, Tracy Rushmer

Caleb Holyoke

No abstract provided.

Graptolite Macroevolution: Phylogenetic Analysis And Testing Foundation Hypotheses Of Directional Change, Daniel Goldman

Daniel Goldman

Funding agency: National Science Foundation Amount: $117,107.00 Year: 2001/4 yrs

Geomagnetic Field Behavior Before And After The Kauai Reverse-Normal Polarity Transition, Scott Bogue

Scott Bogue

New paleomagnetic results from 4 m.y. old lava flows from Kauai, Hawaii, suggest that strong poloidal field is associated with an unusual state of the geodynamo that follows attempts at polarity reversal (successful or not). The new data comprise 50 paleomagnetic sites from superposed lava flows occurring just below and above the Kauai reverse-normal polarity transition. A composite record of 45 distinct field determinations was constructed by combining sites that record similar ancient field and correlating them to previously published results from Kauai. Of the 45 data, 25 include paleointensity estimates derived from double-heating experiments. A comparison of the composite …

Karst Genetic Model For The French Bay Breccia Deposits, San Salvador, Bahamas, Lee J. Florea, John Mylroie, Jim Carew

Lee J Florea, PhD, P.G.

No abstract provided.

Structural And Topographic Evolution Of The Central Transverse Ranges, California, From Apatite Fission- Track, (U-Th)/He And Digital Elevation Model Analyses, Ann Blythe, D Burbank, K Farley, E Fielding

Ann Blythe

No abstract provided.

Fe-Mg Carbonates As A Monitor Phase Of Carbon Dioxide And Oxygen Fugacity On Mars, Andrea Koziol

Andrea M. Koziol

Past Leaded Gasoline Emissions As A Nonpoint Source Tracer In Riparian Systems: A Study Of River Inputs To San Francisco Bay, Charles E. Dunlap, Robin Bouse, A. Russell Flegal

Charles Dunlap

Variations in the isotopic composition of lead in 1995- 1998 river waters flowing into San Francisco Bay trace the washout of lead deposited in the drainage basin from leaded gasoline combustion. At the confluence of the Sacramento and San Joaquin rivers where they enter the Bay, the isotopic compositions of lead in the waters define a linear trend away from the measured historical compositions of leaded gas in California. The river waters are shifted away from leaded gasoline values and toward an isotopic composition similar to Sierra Nevadan inputs which became the predominant source of sedimentation in San Francisco Bay …

Regional Hydrology Of The Dixie Valley Geothermal Field, Nevada: Preliminary Interpretations Of Chemical And Isotopic Data, Gregory Nimz, Cathy Janik, Fraser Goff, Charles Dunlap, Mark Huebner, Dale Counce, Stuart Johnson

Charles Dunlap

Chemical and isotopic analyses of Dixie Valley regional waters indicate several distinct groups ranging in recharge age from Pleistocene (<20 ka) to recent (<50a). Valley groundwater is older than water from perennial springs and artesian wells in adjacent ranges, with Clan Alpine range (east) much younger (most <50a) than Stillwater range (west; most > 1OOOa).Geothermal field fluids (-12-14 ka) appear derived from water similar in composition to non-thermal groundwater observed today in valley artesian wells (also -14 ka). Geothermal fluid interaction with mafic rocks (Humboldt Lopolith) appears to be common, and significant reaction with granodiorite may also occur. Despite widespread occurrence of carbonate rocks, largescale chemical interaction appears minor. Age asymmetry of the ranges, more extensive interaction with deep- seated waters in the west, and distribution of springs and artesian wells suggest the existence …

Geodynamic Interpretation Of Regional Unconformities: Research Fund Eustacy Or Tectonics?, Daniel Goldman

Daniel Goldman

Funding agency: Petroleum Research Fund Investigators: C.E. Mitchell, Dr. Goldman Amount: $ 6,500.00

Experimental Studies Of Fe-Mg Carbonates And Their Role In Petrogenesis

Andrea M. Koziol

Active Tectonics And Ultrahigh-Pressure Rocks, Ann Blythe

Ann Blythe

This chapter compares modern exhumation and surface uplift rates with the rates needed for the preservation of ultrahigh pressure (UHP) metamorphic rocks. The highest recorded exhumation rates of ~ 5–10 mm/a are inferred from isotopic and fission-track analyses in the Himalaya, Southern Alps of New Zealand, and D’Entrecasteaux Islands. Similar rates (~7 mm/a) of surface uplift are measured from leveling surveys in Nepal and correlations of marine terraces in the Southern Alps. In Nepal, however, this surface uplift rate is occurring despite erosion, and the true rate of surface uplift is probably considerably higher. In restraining bends along the San …

Biogeography Of The Late Paleocene Benthic Foraminiferal Extinction, Ellen Thomas

Ellen Thomas

During the Late Paleocene Thermal Maximum (LPTM) benthic foraminifera at middle bathyal and greater depths suffered extinction of 30-50% of species during a few thousand years. Extinction was less severe at neritic to upper bathyal depths, where temporary changes in faunal composition prevailed. Pre-extinction deep-sea faunas were cosmopolitan and diverse, and contained heavily calcified species. Immediate post-extinction faunas were more variable geographically, exhibited low diversity, and were dominated by thin-walled calcareous or agglutinated taxa, possibly because CaCO3 dissolution increased globally from neritic to abyssal depths just before the extinction. These assemblages were dominated either by long-lived taxa such as Nuttallides …

An Experimental Program To Constrain The Properties Of Co2 Fluid At Elevated Pressures And Temperatures, Andrea Koziol

Andrea M. Koziol

Miocene Paleogeography Of West-Central California--Offset Along The San Gregorio-Hosgri Fault Zone, Clarence Hall Jr, Mark Sutherland, Raymond Ingersoll

Mark Sutherland

The major faults that occur in the region are described and the amount of lateral offset used to construct palinspastic maps is given. The longest, most controversial, and most critical fault relative to the palinspastic maps is the San Gregorio-San Simeon-Hosgri fault, which is discussed in detail

Upper Ordovician Graptolites From The North American Midcontinent:University Biostratigraphy, Biofacies, And Sea-Level, Daniel Goldman

Daniel Goldman

Funding agency: The Ohio State University Amount: $23,000.00

An Investigation Of The Stability Of Carbonate Minerals, Andrea Koziol

Andrea M. Koziol

Thermochronology And Thermobarometry In Lithotectonic Zones In Eastern New England, Andrea Koziol, Robert Wintsch

Andrea M. Koziol

Experimental Studies Of Fe-Mg Carbonates As Indicators Of Martian Near-Surface Conditions, Andrea Koziol

Andrea M. Koziol

Acquisition Of An Electron Probe Microanalyzer, Andrea Koziol, Robert Wintsch, Michael Dorais, Edward Ripley, Enrique Merino

Andrea M. Koziol

Petrology And Provenance Of Miocene Sedimentary Rocks, Point Sur, California: Implications For Offset Along The San Gregorio-Hosgri Fault Zone, Mark Sutherland

Mark Sutherland

No abstract provided.

Subduction Of The Caribbean Plate And Basement Uplifts In The Overriding South American Plate, James N. Kellogg, William E. Bonini

James N Kellogg

Abstract. The new tectonic interpretations presented in this paper are based on geologic field mapping and gravity data supplemented by well logs, seismic profiles, and radiometric and earthquake data. The present Caribbean-South American plate boundary is the South Caribbean marginal fault, where subduction is indicated by folding and thrusting in the deformed belt and a seismic zone that dips 30o to the southeast and terminates 200 km below the Maracaibo Basin. The Caribbean-South American convergence rate is estimated as 1.9 +_. 0.3 cm/yr on the basis of the 390-km length of the seismic zone and a thermal equilibration time of …