Publications

The Cenozoic West Antarctic rift system, characterized by Cenozoic bimodal alkalic volcanic rocks, extends over a largely ice-covered area, from the Ross Sea nearly to the Bellingshausen Sea. Various lines of evidence lead to the following interpretation: the transantarctic Mountains part of the rift shoulder (and probably the entire shoulder) has been rising since about 60 Ma, at episodic rates o

The silt-sized heavy mineral assemblage, which is predominantly detrital, has been concentrated in this fraction by hydraulic factors and ranges between 11.8 wt. % of the silt fraction in the sandy sediments near Georges Bank to 3.4% in the clayey silt deposit south of Martha's Vineyard. By contrast, the sand fraction averages only 1.5% heavy minerals. Lateral variability within the silt-sized hea

No abstract available.

This paper is an effort to integrate the geophysical research over the West Antarctic rift system over the past three decades, including new data in the Ross Sea area within the concepts of continental rifting developed for other areas during the past decade. The results of aeromagnetic, seismic and gravity survey are discussed. 

Approximately 6100 km of 3.5-kHz echo-sounding profiles was correlated with a GLORIA side-scan sonar image of the mid-Atlantic United States (34??N, 70??W) lower slope-upper continental rise. The image allows us to map the major erosional and depositional features and to identify major processes that have shaped the area. Interpretation of GLORIA imagery and echo-sounding profiles indicates that m

SeaBeam bathymetric data and GLORIA (Geologic LOng-Range Inclined Asdic) sidescan sonar images of a 175-km-long section of the Florida escarpment in the eastern Guff of Mexico show that this carbonate escarpment has been eroded since its initial formation, but its morphology suggests that erosional processes have not acted uniformly on the escarpment. Parts of the escarpment are notched by box can

This paper proposes a new definition of the groupiness factor, GF, based on the envelope of the incident-wave time series. It is shown that an envelope-based GF has several important advantages over the SIWEH-based groupiness factor, including objective criteria for determining the accuracy of the envelope function and well-defined numerical limits.Using this new GF, the variability of incident wa

An unconformity of 100 m.yr magnitude continues to form on the western edge of the Florida-Bahama Platform, near 26??N, where distal Mississippi Fan sediments are progressively burying the Florida Escarpment. Multiple perspectives of the developing unconformity's morphology are revealed using available technologies including GLORIA images of the entire platform's edge, Seabeam bathymetric contours

Analyses of sidescan-sonar records supplemented by available bathymetric, sedimentary, subbottom, and bottom-current data reveal the distributions of the following three categories of sedimentary environments within the glaciated, topographically complex Boston Harbor estuary in Massachusetts. 1) Environments of erosion appear on the sonographs either as patterns with isolated strong reflections o

The different snow and ice types on a glacier may be subdivided according to the glacier-facies concept. The surficial expression of some facies may be detected at the end of the balance year by the use of visible and near-infrared image data from the Landsat multispectral scanner (MSS) and thematic mapper (TM) sensors. Ice and snow can be distinguished by reflectivity differences in individual or

No abstract available.

This U.S. Geological Survey Open-File Report [extract] contains a listing of publications authored or co-authored by members of the Branch of Atlantic Marine Geology and published in calendar year 1990. The Branch conducts a broad geologic and geophysical research and mapping program, primarily along the U.S. Atlantic Margin, in the Great Lakes, the Gulf of Mexico, the Caribbean and polar regions.