Publications

Cores from a Mississippi outer-fan depositional lobe demonstrate that sublobes at the distal edge contain a complex local network of channelized-turbidite beds of graded sand and debris-flow beds of chaotic silt. Off-lobe basin plains lack siliciclastic coarse-grained beds. The basin-plain mud facies exhibit low acoustic backscatter on SeaMARC IA sidescan sonar images, whereas high...

The most common features are subcircular depressions, commonly compound, that are irregularly distributed across the lake floor. The depressions are most common in the southern basin of the lake where lacustrine sediments are more than a few meters thick, corresponding to water depths greater than about 90 m. We have divided the depressions into three types on the basis of their internal...

The Conoco 145-1 exploratory well, located in the southeastern portion of the Georges Bank Basin, was drilled to a total depth of 4303 m below the sea floor. The oldest sedimentary rocks sampled are of Middle Jurassic age (Late Bathonian-Callovian). A dolomite-limestone-evaporite sequence dominates the section below 3917 m; limestone is the predominant lithology in the intervals of 3271...

The flushing of Boston Harbor, a shallow, tidally dominated embayment with little fresh water input, is investigated using a depth-averaged model. The modeled tidal currents exhibit strong spatial variability and ebb/flood asymmetry due to complex topography and coastline geometry and were verified by shipboard acoustic Doppler current profiler measurements. At the inlets to the harbor...

Since 1985, the Branch of Atlantic Marine Geology has been involved in collecting, processing and digitally mosaicking high and low resolution sidescan sonar data. In the past, processing and digital mosaicking has been accomplished with a dedicated, shore-based computer system. Recent development of a UNIX-based image-processing software system includes a series of task specific...

The West Antarctic rift system, marked by a 3-5-kilometer high shoulder from northern Victoria Land to the Ellsworth Mountains, extends through the Ross Embayment and the Byrd Subglacial Basin. Geophysical data suggest that the ice covered area beneath the rift zone is underlain by Cenozoic volcanic rocks (flood basalts?), and extended crust about 20 km thick. Exposed bimodal alkaline...

No abstract available.

The mechanisms responsible for onshore and offshore sediment fluxes across the shoreface zone seaward of the surf zone were examined in a 3-year field study. The study was conducted in the southern part of the Middle Atlantic Bight in the depth region 7–17 m using instrumented tripods supporting electromagnetic current meters, pressure sensors, suspended sediment concentration sensors...

E-4 is one of eight Geodynamics transects that cross the Atlantic margin of North America between Georgia and Newfoundland. Five of the transects are in the United States and three are in Canada. Transect E-4, which is 110 km wide and more than 1,100 km long, extends from the stable North American craton just west of the Grenville front near Lexington, Kentucky southeastward across Cape...

A two-dimensional, one by two-kilometer section through the seafloor was simulated with a numerical model to investigate coupled fluid and heat flow resulting from basalt intrusions in a buried spreading center. Boundary and initial conditions and physical properties of both sediments and basalt were constrained by field surveys and drilling in the Guaymas Basin, central Gulf of...

Multiple intrusions of gabbros, mafic dikes, and syenites in the Kap Edvard Holm Complex gave rise to prolonged circulation of meteoric hydrothermal solutions and extreme isotope exchange and mineral alteration in the 3600-m-thick Lower Layered Series gabbros. In the Lower Layered Series, δ18O of plagioclase varies from +0.3‰ to -5.8‰, and it decreases with an increase in the volume of...

No abstract available.