Geology Commons^™

Long-Term, Seasonal, And Event-Driven Sediment Movement On East Beach, San Salvador Island, Bahamas, Andrew L. Brill, H. Allen Curran, William T. Fox

Geosciences: Faculty Publications

East Beach is a modern, medium-energy shoreline located on the northeast coast of San Salvador Island, Bahamas. Stake and horizon profiles were made at 9 sites along a 1-km section of the beach in June, 1990, and every six months thereafter through January,1992. These observations appear to confirm that East Beach is a prograding shoreline, building onto the eastern shelf of the island. Seasonally corrected volume calculations indicate that between June, 1990 and January, 1992 approximately 14,000 m³ of new sand per kilometer were added to the East Beach system, with most of the sand likely derived from the …

Sedimentology And Ichnology Of Holocene Dune And Backshore Deposits, Lee Stocking Island, Bahamas, Brian White, H. Allen Curran

Geosciences: Faculty Publications

No abstract provided.

The Holocene Carbonate Eolianites Of North Point And Some Nearby Marine Environments, San Salvador Island, Bahamas: A Field Trip Guide, Brian White, H. Allen Curran

Geosciences: Faculty Publications

See other Smith authored Field Trip Guides of Gerace Research Centre.

Petrology Of The High-Alumina Hoosac Schist From The Chloritoid+Garnet Through The Kyanite+Biotite Zones In Western Massachusetts, John T. Cheney, John B. Brady

Geosciences: Faculty Publications

The eastern limb of the Berkshire anticlinorium of western Massachusetts (Figure 1) is a complex, multiplydeformed, polymetamorphic, Taconian/Acadian orogenic terrane. The geologic framework of this area is well established, originally by the mapping of B.K. Emerson (1892, 1898, 1899) and Pumpelly et al. (1894), as summarized on the Massachusetts geologic map of Emerson (1917), and more recently by the mapping of L.M. Hall, N.L. Hatch, S.A. Norton, P.H. Osberg, N.M. Ratcliffe, and R.S. Stanley, as summarized on the Massachusetts geologic map of Zen et al. (1983). The summary reports of USGS Professional Paper 1366 in 1988 as well as the …

Trace Fossils Of Shallow Subtidal To Dunal Ichnofacies In Bahamian Quaternary Carbonates, H. Allen Curran, Brian White

Geosciences: Faculty Publications

Pleistocene and Holocene carbonate grainstones or calcarenites capping the islands of the Bahamas commonly contain distinctive animal and/or plant trace fossils. Three ichnocoenoses within the Skolithos and Psilonichnus ichnofacies are recognized in the transition from sediments deposited in the shallow shelf environment, commonly associated with coral reefs, to sediments of the coastal dune environment. Analog relationships between the trace fossils and modern tracemakers can be established in many cases, and this correspondence strengthens the interpretive model. Ophiomorpha

and Skolithos linearis characterize beds deposited in shallow shelf settings. Psilonich- nus upsilon, the fossil burrow of the ghost crab Ocypode quadrata …

The Stratigraphy And Ichnology Of A Submarine Cave In The Exuma Cays, Bahamas, H. Allen Curran, Robert F. Dill

Geosciences: Faculty Publications

Reprinted from: Roger J. Bain (ed.), 1991, Proceedings of the Fifth Symposium on the Geology of the Bahamas: San Salvador, Bahamian Field Station.

Comparative Morphologic Analysis And Geochronology For The Development And Decline Of Two Pleistocene Coral Reefs, San Salvador And Great Inagua Islands, Bahamas, H. Allen Curran, Brian White, J. H. Chen, G. J. Wasserburg

Geosciences: Faculty Publications

Reprinted from: John E. Mylroie (ed.), Proceedings of the 4th Symposium on the Geology of the Bahamas: San Salvador, Bahamian Field Station.

Pleistocene And Holocene Carbonate Environments On San Salvador Island, Bahamas: A Field Trip Guide, H. Allen Curran, Roger J. Bain, James L. Carew, John E. Mylroie, James W. Teeter, Brian White

Geosciences: Faculty Publications

Although isolated and small in size, San Salvador Island is in many ways a unique place - an all carbonates setting on a small, tectonically stable platform, surrounded by deep oceanic waters, and an historical footnote as the widely accepted first landing site of Christopher Columbus in the New World in 1492. Columbus' stay here was brief, and the major events of subsequent history largely have passed San Salvador by. This is not a tourist island; the natural beauty, floras, and faunas of the Bahamas are well preserved here.

The overview theme of this series of field excursions on San …

A Field Trip Guide To The Sue Point Fossil Coral Reef San Salvador Island, Bahamas, Brian White

Geosciences: Faculty Publications

See other Smith authored Field Trip Guides of Gerace Research Centre.

Trace Fossils In Carbonate Upper Beach Rocks And Eolianites: Recognition Of The Backshore To Dune Transition, H. Allen Curran, Brian White

Geosciences: Faculty Publications

Reprinted from: H. Allen Curran (ed.), Proceedings of the Third Symposium on the Geology of the Bahamas: Fort Lauderdale, Florida, CCFL Bahamian Field Station

Coral Reef To Eolianite Transition In The Pleistocene Rocks Of Great Inagua, Bahamas, Brian White, H. Allen Curran

Geosciences: Faculty Publications

Great Inagua Island, the southernmost of the chain of Bahamian islands, lies approximately 100 km northeast of the eastern tip of Cuba. This paper reports the results of reconnaissance geologic field work conducted on Great Inagua Island in January, 1985, and of more detailed observations made in January, 1986, near Matthew Town, between South West Point and Devil's Point.

Coarsening Of Fine-Scale Exsolution Lamellae, John B. Brady

Geosciences: Faculty Publications

Diffusional exchange between the wedge-shaped terminations of fine-scale, coherent exsolution lamellae and the large flat sides of adjacent like lamellae is proposed as the principal mechanism for the coarsening of lamellar exsolution textures in silicate minerals. Following the methods of Gibbs (1906), a formula is derived for the chemical potential gradients due to interfacial energy effects that drive the proposed diffusion and coarsening....

Trace Fossils From The Rocky Point Member Of The Peedee Formation (Upper Cretaceous) And The Castle Hayne Limestone (Eocene), H. Allen Curran

Geosciences: Faculty Publications

Trace Fossils From Field Trip no. 8: Eocene Carbonate Facies of the North Carolina Coastal Plain by W. Burleigh Harris, Victor A. Zullos, and Lee J. Otte.

SEPM Third Annual Midyear Meeting, Raleigh, North Carolina,

Trip: September 28-29, 1986

The Cretaceous-Tertiary Boundary On The Cape Fear Arch, North Carolina, U.S.A., W. Burleigh Harris, Paul A. Thayer, H. Allen Curran

Geosciences: Faculty Publications

Petrologic and faunal study of a 72.5m continuous corehole drilled in southeastern North Carolina has provided an opportunity to study a relatively uninterrupted vertical sequence across the Cretaceous-Tertiary boundary. The following stratographic sequence occurs; upper middle Maastrichtian Peedee Formation, –65.8m to –51.8m below sea-level (BMSL), upper middle Maastrichtian Rocky Point Member of the Peedee Formation, –51.8m to –27.4m BMSL, and middle to upper (?) Eocene Castle Hayne Limestone, –27.4m to 15.2m BMSL (base of casing).

The Peedee Formation consists of moderately indurated, very fine to fine, sandy foraminiferal biomicrite and sandy biomicrite. Silt-size zoned dolomite rhombohedra form up to 30% …

Molluscan Shell Transport—You Ain't Seen Nothin' Yet, Orrin H. Pilkey, H. Allen Curran

Geosciences: Faculty Publications

No abstract provided.

The Holocene Carbonate Eolianites Of North Point And The Modern Marine Environments Between North Point And Cut Cay, Brian White, H. Allen Curran

Geosciences: Faculty Publications

The goals of this part of the field trip are to study the types of strata, sedimentary structures, trace fossils, and dune morphologies of the Holocene eolianites excellently exposed along the coasts of Rice Bay and North Point. We will show how eolian deposition of carbonate grains occurs and how dunes are initiated and evolve. Toward the end of this excursion, a short snorkel dive will be conducted in the shallow, sheltered waters between North Point and Cut Cay to study grass beds, sandy substrates, and hardgrounds and to compare their associated sediments, plants, and animals. The area to be …

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 …

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 …

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 …

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 …

Interdiffusion Of K And Na In Alkali Feldspars: Homogenization Experiment, John B. Brady, Richard A. Yund

Geosciences: Faculty Publications

The rates of homogenization of coherent exsolution lamellaein cryptoperthites have been used to evaluate K-Na interdiffusion in alkali feldspars.An "average" interdiffusion coefficient (Ď) is between 2 and 4 x l0^-17 cm²/sec for a synthetic cryptoperthite at 600°C in the composition range Or₂₃-Or₅₃, and between 6 and 12 x 10^-16 cm²/sec for a natural cryptopertlite at 650°C in the composition range Or₀-Or₈₅. These values are for diffusion (801) at 1 atmosphere pressure. K-Na interdiffusion coefficients calculated from published K and Na self-diffusion coefficients and thermochemical solution data …

Trace Fossils In Pleistocene Carbonate Rocks Of San Salvador, Bahamas, H. Allen Curran

Geosciences: Faculty Publications

Reprinted from: D.T. Gerace (ed.), Proceedings of 1st Symposium on Geology of Bahamas, CCFL, Bahamas Field Station, San Salvador, Bahamas

Intergranular Diffusion In Metamorphic Rocks, John B. Brady

Geosciences: Faculty Publications

Theoretical models of intergranular diffusion demonstrate that grain size and grain boundary width are the most important textural parameters influencing diffusion in metamorphic rocks. Taking diffusion in an aqueous solution as a limiting case for diffusion in the intergranular region of metamorphic rocks, it appears that the diffusivities of many species will be similar and relatively insensitive to variations in temperature and pressure over a wide range of metamorphic conditions. Observed variations in the mobility of chemical components during metamorphism may be related principally to variations in the ratio of the component density in the intergranular region to the component …

Diffusion Data For Clinopyroxenes From Homogenization And Self-Diffusion Experiment, John B. Brady, Robert H. Mccallister

Geosciences: Faculty Publications

Kinetic experiments involving the homogenization of fine-scale, coherent (001) pigeonite lamellae in a sub-calcic diopside have been used to constrain Ca-Mg interdiffusion coefficients for clinopyroxenes. At 1150°-1250°C and 25 kbar, "average" Ca-Mg effective binary interdiffusion coefficients are described by

Ď = (3.89 x l0^-7) exp(-360.87 kJ/RT) (m²/sec)

(Ď : (3.89 x l0^-3) exp(-86.25 kcal/RT) (cm²/sec))

with an uncertainty of a factor of 2. Because of the large thermodynamic effect on diffusion near a solvus, actual interdiffusion coefficients should vary by an order of magnitude or more with composition …

Observations On The Paleoecology And Formation Of The “Upper Shell” Unit, Lee Creek Mine, H. Allen Curran, Patricia L. Parker

Geosciences: Faculty Publications

The "Upper Shell" unit at the Lee Creek Mine (Pliocene age, maximum thickness 3 m) is remarkable for its concentration of well-preserved mollusk shells in a sparse quartz sand matrix, and it is dominated by several species of bivalves, with many shells articulated. The unit can be subdivided into three bivalve assemblage zones characterized by associations of dominant species. Zone 1 is dominated by Mercenaria mercenaria, an infaunal, shallow- to medium-burrowing, siphonate clam. Zone 2 is characterized by an epifaunal bivalve assemblage that includes Glycymeris americana, Argopecten eboreus, Anomia simplex, and Ostrea meridionalis. Thin but highly concentrated …

Dunes And Vegetation: Natural Recovery On A Damaged Barrier Island, C. John Burk, H. Allen Curran, Teresa M. Czerniak

Geosciences: Faculty Publications

No abstract provided.

Normalizations Of Thermodynamic Properties And Some Implications For Graphical And Analytical Problems In Petrology, John B. Brady, James H. Stout

Geosciences: Faculty Publications

Petrologic problems may be analyzed using any of a variety of possible choices of units. Although gram-formula units (moles) are commonly used, other units of quantity arc more appropriate for many applications. Gram-atom units offer the numerical simplicity of gram-formula units and have the advantage of being conserva­tive. A conservative unit of quantity is one for which the sum of the units of reactants equals the sum of the units of products in a chemical reaction. For many graphical problems, a conservative unit of quantity, such as gram-atom or mass units, should be used. Since gram-formula units are not conservative, …

Interdiffusion Of S And Se In Tiemannite, Nabil Z. Boctor, John B. Brady

Geosciences: Faculty Publications

Diffusion coefficients for S-Se interdiffusion in tiemannite (HgSe) single crystals have been determined in the temperature range 500"-700oC. The measured diffusivities may be fit by the equation...

A Micro-Analytical Technique For Determination Of Aluminum In Aqueous Solutions, John B. Brady, John D. Frantz

Geosciences: Faculty Publications

A flow-cell colorimetric technique has been developed by which Al concentrations of 0.0003to 0.1 wt. percent can be analyzed in one-microliter fluid samples.An A1-complexing reagent (Ferron) continuously flowing through teflon capillary tubing is spiked with one-microliter aliquots of solutions containing A1. The sample reacts with the reagent and subsequently passes through a microcolorimeter. Measurement of less than one nanomole A1 is possible by comparing the integrated absorbance of unknown samples with standard solutions.