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Full-Text Articles in Physical Sciences and Mathematics
The Birth Of A Forearc: The Basal Great Valley Group, California, Usa, D. A. Orme, Kathleen D. Surpless
The Birth Of A Forearc: The Basal Great Valley Group, California, Usa, D. A. Orme, Kathleen D. Surpless
Geosciences Faculty Research
The Great Valley basin of California (USA) is an archetypal forearc basin, yet the timing, structural style, and location of basin development remain controversial. Eighteen of 20 detrital zircon samples (3711 new U-Pb ages) from basal strata of the Great Valley forearc basin contain Cretaceous grains, with nine samples yielding statistically robust Cretaceous maximum depositional ages (MDAs), two with MDAs that overlap the Jurassic-Cretaceous boundary, suggesting earliest Cretaceous deposition, and nine with Jurassic MDAs consistent with latest Jurassic deposition. In addition, the pre-Mesozoic age populations of our samples are consistent with central North America sources and do not require a …
Facies Architecture And Provenance Of A Boulder-Conglomerate Submarine Channel System, Panoche Formation, Great Valley Group: A Forearc Basin Response To Middle Cretaceous Tectonism In The California Convergent Margin, T. J. Greene, Kathleen D. Surpless
Facies Architecture And Provenance Of A Boulder-Conglomerate Submarine Channel System, Panoche Formation, Great Valley Group: A Forearc Basin Response To Middle Cretaceous Tectonism In The California Convergent Margin, T. J. Greene, Kathleen D. Surpless
Geosciences Faculty Research
Tectonic reorganization induced by a rapid increase in plate motion obliquity and rate beginning at ca. 100 Ma affected California’s Andean-style convergent margin, with concomitant changes in the accretionary prism of the Franciscan Complex, the Great Valley forearc basin, and the Sierran continental arc. Using facies analysis and a combined provenance approach, we suggest that this ca. 100 Ma tectonic signal is preserved in a Cenomanian (Upper Cretaceous) boulder-conglomerate outcrop along the San Luis Reservoir (SLR) in the southern Great Valley, which represents the thickest and coarsest deep-water deposit ever described in the Great Valley Group (GVG). We document a …
Hornbrook Formation, Oregon And California: A Sedimentary Record Of The Late Cretaceous Sierran Magmatic Flare-Up Event, Kathleen D. Surpless
Hornbrook Formation, Oregon And California: A Sedimentary Record Of The Late Cretaceous Sierran Magmatic Flare-Up Event, Kathleen D. Surpless
Geosciences Faculty Research
Early Late Cretaceous time was characterized by a major magmatic flare-up event in the Sierra Nevada batholith and early phases of magmatism in the Idaho batholith, but the sedimentary record of this voluminous magmatism in the U.S. Cordillera is considerably less conspicuous. New detrital zircon U-Pb ages from the Hornbrook Formation in southern Oregon and northern California reveal a significant and sustained influx of 100–85 Ma detrital zircons into the broader Hornbrook region beginning ca. 90 Ma. Detrital zircon ages and hafnium isotopic compositions, combined with whole-rock geochemistry, suggest that sediment was largely derived from the Sierra Nevada, requiring uplift …
Holocene Earthquakes And Late Pleistocene Slip Rate Estimates On The Wassuk Range Fault Zone, Nevada, Usa, J. M. Bormann, Benjamin E. Surpless, M. W. Caffee, S. G. Wesnousky
Holocene Earthquakes And Late Pleistocene Slip Rate Estimates On The Wassuk Range Fault Zone, Nevada, Usa, J. M. Bormann, Benjamin E. Surpless, M. W. Caffee, S. G. Wesnousky
Geosciences Faculty Research
The Wassuk Range fault zone is an 80‐km‐long, east‐dipping, high‐angle normal fault that flanks the eastern margin of the Wassuk Range in central Nevada. Observations from two alluvial fan systems truncated by the fault yield information on the vertical slip rate and Holocene earthquake history along the range front. At the apex of the Rose Creek alluvial fan, radiocarbon dating of offset stratigraphy exposed in two fault trenches shows that multiple earthquakes resulted in 7.0 m of vertical offset along the fault since ∼9400 cal B.P. These data yield a Holocene vertical slip rate of 0.7±0.1 mm/yr. The south trench …
A Detailed Record Of Shallow Hydrothermal Fluid Flow In The Sierra Nevada Magmatic Arc From Low-Δ18o Skarn Garnets, M. E. D'Errico, J. S. Lackey, Benjamin E. Surpless, S. L. Loewy, J. L. Wooden, J. D. Barnes, A. Strickland, J. W. Valley
A Detailed Record Of Shallow Hydrothermal Fluid Flow In The Sierra Nevada Magmatic Arc From Low-Δ18o Skarn Garnets, M. E. D'Errico, J. S. Lackey, Benjamin E. Surpless, S. L. Loewy, J. L. Wooden, J. D. Barnes, A. Strickland, J. W. Valley
Geosciences Faculty Research
Garnet from skarns exposed at Empire Mountain, Sierra Nevada (California, United States) batholith, have variable δ18O values including the lowest known δ18O values of skarn garnet (–4.0‰) in North America. Such values indicate that surface-derived meteoric water was a significant component of the fluid budget of the skarn-forming hydrothermal system, which developed in response to shallow emplacement (∼3.3 km) of the 109 Ma quartz diorite of Empire Mountain. Values of δ18O, measured in situ across single garnet crystals by secondary ion mass spectrometry, vary considerably (up to 7‰) and sometimes abruptly, indicating variable mixing …