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Barbados Ridge; Inner Trench Slope Sedimentation, William J. Cleary, H. Allen Curran, Paul A. Thayer

Geosciences: Faculty Publications

Quaternary sediments of this inner trench slope are chiefly foraminiferal-pteropod-nanno oozes that have been reworked and/or emplaced by gravity currents. These oozes are mixed with volcanogenic sediments and minor amounts of material derived from the insular shelf. Reworking occurs on topographic highs where fines are winnowed out and mass wasting and gravity currents are initiated; these processes ultimately result in the leveling of irregular floors of deeper, intervening slope basins. Petrographic analyses of graded intervals from the basin floors and slopes reveal the sands to be mixtures of planktic foraminifers (35%), pteropods (10%), and fresh, angular volcanic detritus (10-90%). On …

Ichnology Of Pleistocene Carbonates On San Salvador, Bahamas, H. Allen Curran

Geosciences: Faculty Publications

ABSTRACT-Trace fossils, well preserved and in full relief, are present in Pleistocene calcarenites of subtidal, beach, and dune facies on San Salvador, Bahamas. Most prominent are irregular boxworks of Ophiomorpha sp. that occur in current-bedded, medium to coarse skeletal calcarenites in association with fossil coral reefs in the subtidal facies. Ophiomorpha sp. also occurs in beds deposited in a tidal delta environment. Found with Ophiomorpha sp., often in abundance, are vertical burrow tubes assigned to Skolithos linearis. Trace fossils are absent from beds of the lower beach facies, but upper beach facies beds (backshore zone) contain distinctive Y-shaped crab …

Tracemaking Activities Of Crabs And Their Environmental Significance: The Ichnogenus Psilonichnus, Robert W. Frey, H. Allen Curran, S. George Pemberton

Geosciences: Faculty Publications

Modem crabs are common inhabitants of shallow subtidal, intertidal, and supratidal environments, and many crabs are capable of producing traces that can be preserved in the rock record. The first crabs, Early Jurassic in age, probably were not fossorial. By Cretaceous time, however, diverse endobenthic lineages were established. Many representatives of these lineages undoubtedly produced domiciles that are preserved in shallow marine to quasimarine sediments and that should be useful in characterizing the depositional environment of the sediments. Nonetheless, most such dwelling structures have been studied little and remain essentially unnamed.

The ichnogenus Psilonichnus Fiirsich is amenable to the taxonomic …

Turbulent Suppression Of Spinodal Decomposition, D. J. Pine, Nalini Easwar, James V. Maher, W. I. Goldburg

Physics: Faculty Publications

Light scattering experiments reveal a strong suppression of phase separation near the critical point of a vigorously stirred binary liquid mixture. For stirring Reynolds numbers R ranging from 6.0 × 10³ to 4.5 × 10³, the apparent critical temperature is depressed by ∼1 mK to ∼50 mK. This temperature depression ΔT_c can be fitted to a power law ΔT_c∼Rλ where λ∼2. The magnitude of ΔT_c is consistent with simple models which attribute the effect to the suppression of composition fluctuations by shear; however, these models predict λ≃0.80 in contrast to the observed value …

A Re-Examination Of The Reactions Of Cyanide With Cytochrome C Oxidase, M. G. Jones, D. Bickar, M. T. Wilson, M. Brunori, A. Colosimo, P. Sarti

Chemistry: Faculty Publications

Experiments were performed to examine the cyanide-binding properties of resting and pulsed cytochrome c oxidase in both their stable and transient turnover states. Inhibition of the oxidation of ferrocytochrome c was monitored as a function of cyanide concentration. Cyanide binding to partially reduced forms produced by mixing cytochrome c oxidase with sodium dithionite was also examined. A model is presented that accounts fully for cyanide inhibition of the enzyme, the essential feature of which is the rapid, tight, binding of cyanide to transient, partially reduced, forms of the enzyme populated during turnover. Computer fitting of the experimentally obtained data to …

Carbon Monoxide-Driven Reduction Of Ferric Heme And Heme Proteins, D. Bickar, C. Bonaventura, J. Bonaventura

Chemistry: Faculty Publications

Oxidized cytochrome c oxidase in a carbon monoxide atmosphere slowly becomes reduced as shown by changes in its visible spectra and its reactivity toward oxygen. The 'autoreduction' of cytochrome c oxidase by this procedure has been used to prepare mixed valence hybrids. We have found that this process is a general phenomenon for oxygen-binding heme proteins, and even for isolated hemin in basic aqueous solution. This reductive reaction may have physiological significance. It also explains why oxygen-binding heme proteins become oxidized much more slowly and appear to be more stable when they are kept under a CO atmosphere. Oxidized α …

Field Guide To The Cockburn Town Fossil Coral Reef, San Salvador, Bahamas, H. Allen Curran, Brian White

Geosciences: Faculty Publications

James W. Teeter (ed.), 1984, Proceedings of the 2nd Symposium on the Geology of the Bahamas:San Salvador, CCFL Bahamian Field Station

A Shallowing-Upward Sequence In A Pleistocene Coral Reef And Associated Facies, San Salvador, Bahamas, Brian White, Karen J. Kurkjy, H. Allen Curran

Geosciences: Faculty Publications

The Sangamon-age Cockburn Town fossil coral reef complex displays a vertical sequence of facies from coral reef and closely associated subtidal carbonate sands, through beach calcarenites, to eolianites. This upward change reflects a progressive lowering of sea level and the eventual emergence of the reef complex into a subaerial environment. The contact between upper beach sediments and eolianites is at +4 m providing a minimum for the sea level high stand. Essentially in situ Acropora palmata suggests a sea level of at least 5 to 6 m above present. These values are similar to Sangamon-age high stands reported from New …