Filters: Tags: Strontuim isotope geochronology (X)
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In areas of low uplift rate on the Pacific Coast of North America, reoccupation of emergent marine terraces by later high-sea stands has been hypothesized to explain the existence of thermally anomalous faunas (mixtures of warm and cool species) of last interglacial age. If uplift rates have been low for much of the Quaternary, it follows that higher (older) terraces should also show evidence of reoccupation. Strontium isotope analyses of fossils from a high-elevation marine terrace on Anacapa Island, California yield a suite of ages ranging from ~2.4-2.3 Ma to ~1.4-1.5 Ma. These results indicate that terrace reoccupation and fossil mixing on Anacapa Island could have taken place over several interglacial periods...
Categories: Data;
Tags: Anacapa Island,
California,
Channel Islands National Park,
Climatology,
Geochemistry,
Studies of marine terraces and their fossils can yield important information about sea level history, tectonic uplift rates, and paleozoogeography. The marine terrace record on Santa Rosa Island, California is complex. Two prominent low-elevation terraces appear to record the ~80 ka (MIS 5a) and ~120 ka (MIS 5e) high-sea stands, based on U-series dating of fossil corals, but interpretations are tentative because of clear indications of open-system behavior with respect to U-series nuclides. Nevertheless, low uplift rates are implied by a preferred interpretation of the ages. It is inferred that low late Pleistocene uplift rates, combined with glacial isostatic adjustment (GIA) processes likely resulted in reoccupation...
Categories: Data;
Tags: California,
Channel Islands National Park,
Climatology,
Geomorphology,
Land Use Change,
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