Mary McGann
Research Geologist at the USGS Pacific Coastal and Marine Science Center
Science and Products
Filter Total Items: 13
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Filter Total Items: 67
Paleoceanographic changes on the Farallon Escarpment off central California during the last 16,000 years
New benthic and planktic foraminiferal assemblage census data and Benthic Foraminiferal Oxygen Index (BFOI) values, previously published marine climate proxy data (stable isotopes and Ca/Cd), and unpublished results of total carbon, organic carbon, and calcium carbonate analyses of sediments recovered off central California on the Farallon Escarpment (1605m water depth; 37??13.4???N, 123??14.6???W
Authors
M. McGann
The elusive character of discontinuous deep-water channels: New insights from Lucia Chica channel system, offshore California
New high-resolution autonomous underwater vehicle (AUV) seafloor images, with 1 m lateral resolution and 0.3 m vertical resolution, reveal unexpected seafloor rugosity and low-relief (<10 m), discontinuous conduits over ∼70 km2. Continuous channel thalwegs were interpreted originally from lower-resolution images, but newly acquired AUV data indicate that a single sinuous channel fed a series of di
Authors
K.L. Maier, A. Fildani, C. K. Paull, S.A. Graham, T.R. McHargue, D.W. Caress, Mary McGann
Submarine mass transport within Monterey Canyon: Benthic disturbance controls on the distribution of chemosynthetic biological communities
Documenting mass transport within Monterey Canyon and Fan has been a focus of remotely operated vehicle (ROV) observations, sampling, monitoring, and multibeam mapping studies. These efforts indicate that major mass transport events occur within upper Monterey Canyon (<2 km water depths) with a sub-annual recurrence frequency. However, 14C-stratigraphies indicate that a sand carrying event has not
Authors
Charles K. Paull, B. Schlining, W. Ussler, E. Lundsten, James P. Barry, D. W. Caress, D. E. Johnson, Mary McGann
Rapid climatic signal propagation from source to sink in a southern California sediment-routing system
Terrestrial source areas are linked to deep-sea basins by sediment-routing systems, which only recently have been studied with a holistic approach focused on terrestrial and submarine components and their interactions. Here we compare an extensive piston-core and radiocarbon-age data set from offshore southern California to contemporaneous Holocene climate proxies in order to test the hypothesis t
Authors
J.A. Covault, B.W. Romans, A. Fildani, M. McGann, S.A. Graham
Review of impacts of contaminated sediment on microfaunal communities in the Southern California Bight
A comparison of foraminiferal faunal trends in pristine and impacted regions on the continental shelf and slope of the Southern California Bight, as well as variations in the temporal foraminiferal distribution patterns from 1955 to 1998, suggest that the benthic microfaunal communities have been greatly affected by the presence of contaminated sediment near the major outfall sites. Six species we
Authors
Mary McGann
Late Quaternary sediment-accumulation rates within the inner basins of the California Continental Borderland in support of geologic hazard evaluation
An evaluation of the geologic hazards of the inner California Borderland requires determination of the timing for faulting and mass-movement episodes during the Holocene. Our effort focused on basin slopes and turbidite systems on the basin floors for the area between Santa Barbara and San Diego, California. Dating condensed sections on slopes adjacent to fault zones provides better control on fau
Authors
W. R. Normark, M. McGann, R. W. Sliter
Comments on potential geologic and seismic hazards affecting proposed liquefied natural gas site in Santa Monica Bay, California
In a letter to the U.S. Geological Survey (USGS) dated March 25, 2008, Representative Jane Harman (California 36th district) requested advice on geologic hazards that should be considered in the review of a proposed liquefied natural gas (LNG) facility off the California coast in Santa Monica Bay. In 2004, the USGS responded to a similar request from Representative Lois Capps, regarding two propos
Authors
Stephanie L. Ross, Homa J. Lee, Tom E. Parsons, Larry A. Beyer, David M. Boore, James E. Conrad, Brian D. Edwards, Michael A. Fisher, Arthur D. Frankel, Eric L. Geist, Kenneth W. Hudnut, Susan E. Hough, Robert E. Kayen, T.D. Lorenson, Nicolas Luco, Patricia A. McCrory, Mary McGann, Manuel Nathenson, Michael Nolan, Mark D. Petersen, Daniel J. Ponti, Charles L. Powell, Holly F. Ryan, John C. Tinsley, Chris J. Wills, Florence L. Wong, Jingping Xu
Interferometric Sidescan Bathymetry, Sediment and Foraminiferal Analyses; a New Look at Tomales Bay, California
The United States Geological Survey (USGS) in collaboration with Point Reyes National Sea Shore (PRNS), and the Tomales Bay Watershed Council [http://www.tomalesbaywatershed.org/] has completed a detailed bathymetric survey, and sediment and foraminiferal analyses of the floor of Tomales Bay, California. The study goals are to detail the submarine morphology, the sediment distribution, sedimentar
Authors
Roberto J. Anima, John L. Chin, David P. Finlayson, Mary McGann, Florence L. Wong
High-resolution foraminiferal, isotopic, and trace element records from holocene estuarine deposits of San Francisco Bay, California
A 3.5-m gravity core (DJ6-93SF-6) from San Francisco Bay reveals a complex paleoclimatic history of the region over the last 3870 cal YBP. A polynomial equation based on 11 AMS 14C ages provides an excellent age model for the core, and environmental proxies for water temperature and salinity are derived from various foraminiferal abundances, stable carbon and oxygen isotopes, and Mg/Ca ratios. Two
Authors
M. McGann
Geomorphological, depositional, and foraminiferal indicators of late Quaternary tectonic uplift in Iskenderun Bay, Turkey
Iskenderun Bay is a major shallow embayment in the eastern part of the Mediterranean Sea, where the African and Anatolian Plates converge. This tectonically active basin was investigated for oceanographic, sedimentological, geochemical, and foraminiferal parameters. On the basis of the data acquired, the distribution of living and fossil foraminifera in 284 grab and 54 gravity core samples was det
Authors
Valentina Yanko-Hombach, H. Koral, Niyazi Avsar, Irena Motnenko, Mary McGann
Age of Palos Verdes submarine debris avalanche, southern California
The Palos Verdes debris avalanche is the largest, by volume, late Quaternary mass-wasted deposit recognized from the inner California Borderland basins. Early workers speculated that the sediment failure giving rise to the deposit is young, taking place well after sea level reached its present position. A newly acquired, closely-spaced grid of high-resolution, deep-tow boomer profiles of the debri
Authors
W. R. Normark, M. McGann, R. Sliter
Science and Products
Filter Total Items: 13
No Result Found
Filter Total Items: 67
Paleoceanographic changes on the Farallon Escarpment off central California during the last 16,000 years
New benthic and planktic foraminiferal assemblage census data and Benthic Foraminiferal Oxygen Index (BFOI) values, previously published marine climate proxy data (stable isotopes and Ca/Cd), and unpublished results of total carbon, organic carbon, and calcium carbonate analyses of sediments recovered off central California on the Farallon Escarpment (1605m water depth; 37??13.4???N, 123??14.6???W
Authors
M. McGann
The elusive character of discontinuous deep-water channels: New insights from Lucia Chica channel system, offshore California
New high-resolution autonomous underwater vehicle (AUV) seafloor images, with 1 m lateral resolution and 0.3 m vertical resolution, reveal unexpected seafloor rugosity and low-relief (<10 m), discontinuous conduits over ∼70 km2. Continuous channel thalwegs were interpreted originally from lower-resolution images, but newly acquired AUV data indicate that a single sinuous channel fed a series of di
Authors
K.L. Maier, A. Fildani, C. K. Paull, S.A. Graham, T.R. McHargue, D.W. Caress, Mary McGann
Submarine mass transport within Monterey Canyon: Benthic disturbance controls on the distribution of chemosynthetic biological communities
Documenting mass transport within Monterey Canyon and Fan has been a focus of remotely operated vehicle (ROV) observations, sampling, monitoring, and multibeam mapping studies. These efforts indicate that major mass transport events occur within upper Monterey Canyon (<2 km water depths) with a sub-annual recurrence frequency. However, 14C-stratigraphies indicate that a sand carrying event has not
Authors
Charles K. Paull, B. Schlining, W. Ussler, E. Lundsten, James P. Barry, D. W. Caress, D. E. Johnson, Mary McGann
Rapid climatic signal propagation from source to sink in a southern California sediment-routing system
Terrestrial source areas are linked to deep-sea basins by sediment-routing systems, which only recently have been studied with a holistic approach focused on terrestrial and submarine components and their interactions. Here we compare an extensive piston-core and radiocarbon-age data set from offshore southern California to contemporaneous Holocene climate proxies in order to test the hypothesis t
Authors
J.A. Covault, B.W. Romans, A. Fildani, M. McGann, S.A. Graham
Review of impacts of contaminated sediment on microfaunal communities in the Southern California Bight
A comparison of foraminiferal faunal trends in pristine and impacted regions on the continental shelf and slope of the Southern California Bight, as well as variations in the temporal foraminiferal distribution patterns from 1955 to 1998, suggest that the benthic microfaunal communities have been greatly affected by the presence of contaminated sediment near the major outfall sites. Six species we
Authors
Mary McGann
Late Quaternary sediment-accumulation rates within the inner basins of the California Continental Borderland in support of geologic hazard evaluation
An evaluation of the geologic hazards of the inner California Borderland requires determination of the timing for faulting and mass-movement episodes during the Holocene. Our effort focused on basin slopes and turbidite systems on the basin floors for the area between Santa Barbara and San Diego, California. Dating condensed sections on slopes adjacent to fault zones provides better control on fau
Authors
W. R. Normark, M. McGann, R. W. Sliter
Comments on potential geologic and seismic hazards affecting proposed liquefied natural gas site in Santa Monica Bay, California
In a letter to the U.S. Geological Survey (USGS) dated March 25, 2008, Representative Jane Harman (California 36th district) requested advice on geologic hazards that should be considered in the review of a proposed liquefied natural gas (LNG) facility off the California coast in Santa Monica Bay. In 2004, the USGS responded to a similar request from Representative Lois Capps, regarding two propos
Authors
Stephanie L. Ross, Homa J. Lee, Tom E. Parsons, Larry A. Beyer, David M. Boore, James E. Conrad, Brian D. Edwards, Michael A. Fisher, Arthur D. Frankel, Eric L. Geist, Kenneth W. Hudnut, Susan E. Hough, Robert E. Kayen, T.D. Lorenson, Nicolas Luco, Patricia A. McCrory, Mary McGann, Manuel Nathenson, Michael Nolan, Mark D. Petersen, Daniel J. Ponti, Charles L. Powell, Holly F. Ryan, John C. Tinsley, Chris J. Wills, Florence L. Wong, Jingping Xu
Interferometric Sidescan Bathymetry, Sediment and Foraminiferal Analyses; a New Look at Tomales Bay, California
The United States Geological Survey (USGS) in collaboration with Point Reyes National Sea Shore (PRNS), and the Tomales Bay Watershed Council [http://www.tomalesbaywatershed.org/] has completed a detailed bathymetric survey, and sediment and foraminiferal analyses of the floor of Tomales Bay, California. The study goals are to detail the submarine morphology, the sediment distribution, sedimentar
Authors
Roberto J. Anima, John L. Chin, David P. Finlayson, Mary McGann, Florence L. Wong
High-resolution foraminiferal, isotopic, and trace element records from holocene estuarine deposits of San Francisco Bay, California
A 3.5-m gravity core (DJ6-93SF-6) from San Francisco Bay reveals a complex paleoclimatic history of the region over the last 3870 cal YBP. A polynomial equation based on 11 AMS 14C ages provides an excellent age model for the core, and environmental proxies for water temperature and salinity are derived from various foraminiferal abundances, stable carbon and oxygen isotopes, and Mg/Ca ratios. Two
Authors
M. McGann
Geomorphological, depositional, and foraminiferal indicators of late Quaternary tectonic uplift in Iskenderun Bay, Turkey
Iskenderun Bay is a major shallow embayment in the eastern part of the Mediterranean Sea, where the African and Anatolian Plates converge. This tectonically active basin was investigated for oceanographic, sedimentological, geochemical, and foraminiferal parameters. On the basis of the data acquired, the distribution of living and fossil foraminifera in 284 grab and 54 gravity core samples was det
Authors
Valentina Yanko-Hombach, H. Koral, Niyazi Avsar, Irena Motnenko, Mary McGann
Age of Palos Verdes submarine debris avalanche, southern California
The Palos Verdes debris avalanche is the largest, by volume, late Quaternary mass-wasted deposit recognized from the inner California Borderland basins. Early workers speculated that the sediment failure giving rise to the deposit is young, taking place well after sea level reached its present position. A newly acquired, closely-spaced grid of high-resolution, deep-tow boomer profiles of the debri
Authors
W. R. Normark, M. McGann, R. Sliter