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Full-Text Articles in Physical Sciences and Mathematics
Low Temperature Magnetic Properties Of Siderite And Magnetite In Marine Sediments, Bernard A. Housen, S. K. Banerjee, B. M. Moskowitz
Low Temperature Magnetic Properties Of Siderite And Magnetite In Marine Sediments, Bernard A. Housen, S. K. Banerjee, B. M. Moskowitz
Geology Faculty Publications
Low temperature magnetic techniques provide useful tools to detect the presence of magnetite and pyrrhotite in sediments through identification of their low temperature transitions, to determine the amount of ultrafine-grained (superparamagnetic) material in sediments, and can potentially detect the presence of certain types of magnetotactic bacteria. Application of these types of experiments to nannofossil chalks from beneath the Barbados accretionary prism led to some unusual results, which are attributed to the presence of siderite. Thermal demagnetization of low-temperature remanence after cooling in zero field and in a 2.5 T field both displayed large remanence losses from 20 K to 40 …
Naticid Gastropod Prey Selectivity Through Time And The Hypothesis Of Escalation, Patricia H. Kelley, Thor A. Hansen
Naticid Gastropod Prey Selectivity Through Time And The Hypothesis Of Escalation, Patricia H. Kelley, Thor A. Hansen
Geology Faculty Publications
The hypothesis of escalation posits that biologic hazards such as predation have increased during the Phanerozoic. Previously, a survey of drilling frequencies in the Cretaceous and Paleogene of the North American Coastal Plain suggested an episodic pattern of escalation within the naticid gastropod predator-prey system. This study examines escalation from the perspective of naticid prey selectivity. If escalation occurred within the system, less selectivity of prey may be apparent in the Paleogene compared to younger assemblages. We test this hypothesis for four Eocene Coastal Plain assemblages. Contrary to predictions, intraspecific prey size selectivity was well developed for nine of eleven …
Timing Of Latest Eocene Molluscan Extinction Patterns In Mississippi, David M. Hassl, Thor A. Hansen
Timing Of Latest Eocene Molluscan Extinction Patterns In Mississippi, David M. Hassl, Thor A. Hansen
Geology Faculty Publications
Molluscs removed from 12 bulk samples of the Yazoo Formation (upper Eocene), exposed in a quarry at Cynthia, Mississippi, are similar in com- position and diversity to those found in the underlying upper Eocene Moodys Branch Formation, when dif- ferences in outcrop area are considered (74% of the Yazoo species are also found in the Moodys Branch). This suggests there was no significant extinction during the late Eocene (at the P15/P16 biozone boundary) as has been reported for planktic foraminifera. Only 11.4% of the species from the Yazoo extend into the Oligocene Red Bluff Formation, suggesting a large molluscan extinction …