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James K. Crouch

Publications and source records attributed to James K. Crouch.

8 recordsLinked to original sources
USGS2009

Basin development along the Late Mesozoic and Cainozoic California Margin: A plate tectonic margin of subduction, oblique subduction and transform tectonics

Along the Californian margin of the North American plate, the configuration and structural stability of late Mesozoic and Cainozoic basins are related to plate kinematics. Three tectonic regimes are recorded; orthogonal high-angle subduction, oblique low-angle subduction, and transform slip. During the first, regionally extensive forearc basins developed; during the second and third, borderland settings formed as a consequence of wrench faulting. In the forearc basins, sedimentological facies constitute regional belts that persist for hundreds of kilometres, with stratigraphic sequences that are 1–15 km thick. Shorelines are relatively straight, shelf facies are broad and well developed, and basin fill is composed of shallow marine, shelf and coalescing submarine-fan facies. Sediment transport in the deeper water facies commonly is parallel to the basin axis. Borderland basins reflect tectonic instability. A principal effect of wrench tectonics is the vertical reciprocation of crustal blocks. Shorelines are generally irregular, and narrow shelves pass abruptly into deep basins. Lithofacies change dramatically along strike, and stratigraphic thicknesses are variable from basin to basin, from tens of metres up to 6 km. Basin-margin facies are marked by unconformities, slump aprons, lithological pinch-outs and submarine canyon channels. Penecontemporaneous slip along the basin-margin faults complicates these lithofacies patterns. Borderland type palaeogeography is most extensively developed in the transform tectonic regime, and therefore the more seaward offshore basins are relatively depleted of terrigenous debris owing to transport barriers.

California↗
USGS1979

Comparison of Miocene provincial foraminiferal stages to coccolith zones in the California Continental Borderland

Biostratigraphic ages determined by planktic coccoliths and benthic foraminifera for the same core samples from the California Continental Borderland suggest that a significant overlap exists among provincial Miocene stages of California and that some of the benthic foraminifera commonly used to recognize these stages are time-transgressive. For example, samples assigned to the middle Miocene Discoaster exilis Zone of coccoliths (∼ 14 ± 1 m.y.) are also assigned to the Relizian, Luisian, and lower Mohnian Stages on the basis of benthic foraminifera. Significantly, most past and current geologic interpretations of Cenozoic marine sequences in California rely heavily on provincial benthic foraminiferal stages and zones. Thus, the apparent overlapping of provincial stages has serious implications for geologic studies of the California Cenozoic and should be further investigated in sections onshore.

California↗
USGS1978

Multichannel seismic reflection and sonobuoy refraction data in the outer southern California Borderland

During the L1-78-SC cruise of the USGS research vessel S. P. Lee (April 25 - May 11, 1978) seven sonobuoy profiles and 200 km of 24-channel seismic reflection data were recorded in the outer southern California Continental Borderland. These data were obtained, at the request of the Deep Sea Drilling Project (DSDP), to evaluate possible drill sites along the southern California continental margin. The drill sites shown in Figure 1 were proposed by the Ocean Paleo-environmental Panel for DSDP Leg 63--secheduled for Sept. - Nov. 1978. These sites were selected in order to provide an expanded Neogene record of paleoceanographic-paleoclimatic events and associated evolutionary development of planktic communities along the eastern side of the north Pacific Ocean. Site selection was made prior to this survey on the basis of available single-channel seismic reflection profiles. Thus, the proposed sites shown on Fig. 1 may be relocated or eliminated when the data presented in this report are incorporated with earlier data. The combined data will be evaluated for safety and pollution hazards by Leg 63 site proponents and the DSDP safety panels. The ship's tracks (Fig. 1) were located by an integrated Satellite-Loran C-Doppler Sonar navigation system. Average survey speed was about 5 kts. A 1326 cu in (21,723 CC) tuned air gun array provided the sound source for both reflection and refraction profiles. The air gun array was fired at 50 m (about 18 sec.) intervals by the integrated navigation system.

California↗
USGS1974

Tectonic significance of the Kodiak-Bowie seamount chain, northeastern Pacific

The hypothesis of a fixed melting spot reference frame (M) for relative plate motion is tested in the northeastern Pacific Ocean, where the Kodiak-Bowie seamount chain intersects the northern triple junction between the Pacific, American, and Juan de Fuca plates. Available age determinations on Kodiak and Giacomini Seamounts provide an estimated average rate of volcanic propagation along the chain of 6.5 cm per yr and allow estimates of plate movements relative to the melting spot. The inferred motion of the American plate relative to M is close to that observed along the Yellowstone-Snake River Plain volcanic trend and broadly supports the concept of a fixed melting spot reference frame. However, the convex northward curvature of the Kodiak-Bowie chain and of several chains to the south does not support the hypothesis. The lack of parallelism between these seamounts and the Hawaiian chain suggests slow relative movement between the Kodiak-Bowie and Hawaiian melting spots.

Geology↗