Ginger Barth | United States Geological Survey (original) (raw)

Papers by Ginger Barth

Research paper thumbnail of A Fresh Look at the Geologic Evolution of Kingman Reef and Palmyra Atoll, U.S. Line Islands

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Research paper thumbnail of Possible deep-water gas hydrate accumulations in the Bering Sea

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Research paper thumbnail of The Effect of Plate Structure on Intraplate Volcanism, Kodiak-Bowie Seamount Chain, Gulf of Alaska

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Research paper thumbnail of Multiple melt source origin of the Line Islands (Pacific Ocean)

Geology, 2021

The Line Islands volcanic chain in the central Pacific Ocean exhibits many characteristics of a h... more The Line Islands volcanic chain in the central Pacific Ocean exhibits many characteristics of a hotspot-generated seamount chain; however, the lack of a predictable age progression has stymied previous models for the origin of this feature. We combined plate-tectonic reconstructions with seamount age dates and available geochemistry to develop a new model that involves multiple melt regions and multiple melt delivery styles to explain the spatial and temporal history of the Line Islands system. Our model identifies a new melt source region (Larson melt region at ~17°S, ~125°W) that contributed to the formation of the Line Islands, as well as the Mid-Pacific Mountains and possibly the Pukapuka Ridge.

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Research paper thumbnail of Did the Bering Sea Form as a Cenozoic Backarc Basin

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Research paper thumbnail of Scientific Oceanic Drilling (Iodp) to Test Contrasting Hypotheses for the Origin of the Aleutian Subduction Zone, Aleutian Arc, and Backarc Aleutian Basin

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Research paper thumbnail of Stratigraphic Complexity and Basement Structure in the Western Aleutian Basin of the Bering Sea

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Research paper thumbnail of Deep-Water Acoustic Anomalies from Methane Hydrate in the Bering Sea

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Research paper thumbnail of Continental margins and the U.S. extended continental shelf project

“Margins are where the action is.” With these auspicious words, the opening article of the fi rst... more “Margins are where the action is.” With these auspicious words, the opening article of the fi rst MARGINS newsletter began in spring, 1998. Now, a dozen years later, as the GeoPRISMS followon program begins, the same words resonate for studies related to the Law of the Sea Convention (LOS). The LOS is an international treaty which sets forth a comprehensive framework governing uses of the oceans. The Convention has been in effect since 1994, and there are now 157 parties to the Convention. LOS addresses many maritime issues. Just one article (Article 76) deals with the use of geological and geophysical data. Continental margins are the areas where coastal nations, using criteria established in LOS, are defining the outer limits of the region where they can exercise their exclusive rights to explore, develop, conserve, and manage the living and non-living resources of the seafl oor and sub-seafl oor. Forty-three coastal nations have proposed their outer limits since 2001 (www.un.org/Depts/los/clcs_ new/commission_submissions.htm), and another 28 have formally expressed their intention to do so (www.un.org/Depts/los/ clcs_new/commission_preliminary.htm), generating much action and interest in renewed mapping of continental margins around the globe. The process of defi ning these outer limits provides marine geoscientists excellent opportunities for collecting geological, geophysical, and hydrographic

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Research paper thumbnail of Long-Offset Seismic Investigations of the Deep Bering Sea

ABSTRACT

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Research paper thumbnail of Detrital Zircon Geochronology of the Bering Sea, Shelf to Deep Basin: Climatic and Eustatic Influence on Sediment Transport Pathways

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Research paper thumbnail of The Case for Scientific Drilling in the Aleutian Basin

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Research paper thumbnail of Why Hydrate-linked Velocity-amplitude Anomaly Structures are Common in the Bering Sea Basin: A Hypothesis

The thick sedimentary sequence (2–12 km [6500–39,400 ft]) underlying the abyssal floors (3–4 km [... more The thick sedimentary sequence (2–12 km [6500–39,400 ft]) underlying the abyssal floors (3–4 km [9800–13,100 ft]) of the Bering Sea Basin is shallowly (360 m [1181 ft]) underlain by large (2 km [6500 ft] in diameter, 200 m [656 ft] thick) deposits of concentrated methane hydrate. Mound-shaped bodies of hydrate are displayed on seismic reflection records as velocity-amplitude anomaly (VAMP) structures imaged as velocity pull-ups overlying push-downs. The VAMPs are numerous (hundreds to thousands) and occur across an area of approximately 250,000 km2 (96,525 mi2). The abundance of VAMP structures is conjectured to be a consequence of high rates of basinwide planktonic productivity; of preservation of organic matter; biosiliceous sedimentation; of silica diagenesis; and of high heat flow; and deposition of a thick (700–1000 m [2296–3281 ft]), upper section of perhaps latest Miocene but mostly glacial-age (early Pliocene and Quaternary) turbidite beds and diatom ooze. Stacking of this upper Cenozoic sequence of water-rich beds heated underlying diatomaceous deposits of Miocene and older age and enhanced the generation of thermogenic methane and the diagenetic conversion of the opal A of porous diatom beds to the denser and contractionally fractured opal-cristobalite tridymite phase of porcellaneous shale. Silica transformation expelled large volumes of interstitial and silica-bound water that, with methane, ascended through the shale via chimneys of fracture pathways to enter the porous (60%) upper Cenozoic section of diatom ooze and turbidite beds. Ascending methane entered the hydrate stability field at approximately 360 m (1180 ft), above which concentrated deposits of methane hydrate formed as either pore-filling accumulations or more massive lenses. The deposition of high-velocity methane hydrate above a multitude of chimney structures transporting low-velocity, gas-charged fluids toward the sea floor is posited to account for the widespread recording of VAMP structures in the Bering Sea Basin.

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Research paper thumbnail of Geological and Sediment Thickness Data Sources From the U.S. Continental Margins

Although the United States has not yet ratified the United Nations Convention on the Law of the S... more Although the United States has not yet ratified the United Nations Convention on the Law of the Sea (UNCLOS), work has begun to assess the geophysical and geological data sources that might be applied to an extended continental shelf submission under Article 76 of the UNCLOS. The U.S. Geological Survey, as a follow-up to the Congressional Report published by the

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Research paper thumbnail of Aleutian basin oceanic crust

Earth and Planetary Science Letters, 2015

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Research paper thumbnail of The King Range Terrane of the Franciscan Complex, Cape Mendocino Region, Northern California: Product of Miocene and Younger Interaction of Evolving, Multi-Strand Mendocino Transform with Pacific and North American Plates

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Research paper thumbnail of Methane gas volume expansion ratios and ideal gas deviation factors for the deep-water Bering Sea basins

Open File Report, 2005

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Research paper thumbnail of Continental margins and the U.S. extended continental shelf project

Margins Geoprisms Newsletter, 2010

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Research paper thumbnail of Possible deep-water gas hydrate accumulations in the Bering Sea

Fire in the Ice, 2006

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Research paper thumbnail of Natural Gas and Hydrate Accumulations in the Aleutian Basin of the Bering Sea

The deep water Aleutian Basin of the Bering Sea is a major storehouse of trapped greenhouse gases... more The deep water Aleutian Basin of the Bering Sea is a major storehouse of trapped greenhouse gases. Preliminary volume estimates based on seismic reflection observations easily approach 1000 Tcf of natural gas within the basin. USGS seismic reflection data from the deep water (>3500 m) Bering Sea region include over 20,000 km of single channel profiles coincident with GLORIA sonar tracks acquired during the 1986-7 EEZscan program, plus several older multichannel lines also crossing the deep water Aleutian and Bowers Basins. These airgun-source data all provide images from seafloor to basement, over 3 km of penetration. The basin fill includes generally horizontal and uniform sedimentary reflection sequences, comprising predominantly mudstones and distal turbidites, upon oceanic crust of probable Cretaceous age. In seismic reflection images of these flat-lying sediments, methane chimneys overlain by hydrate caps stand out as distinctive velocity pseudostructures. These velocity-amplitude anomaly structures ("VAMPs") characteristically include a zone of velocity pull-up (attributed to high-seismic-velocity hydrate within the sediment) directly overlying a zone of velocity push-down (attributed to low-seismic-velocity gas in the pore spaces). A prominent hydrate bottom simulating reflection (BSR) is also present throughout the basin. Within the VAMPs, the BSR roughly separates the pull-up from the push-down. Hundreds of VAMPs have been imaged, and thousands must exist within the deep water basin. Individual examples vary widely in lateral extent, focused appearance, and amplitude effects. Some also present a seafloor manifestation of slight doming. Five example case studies are presented, focusing particularly on interval travel time anomalies and quantitative interpretation in terms of presence of hydrate and free gas. Individual large VAMPs (1-3 km across, ˜30 ms pull-up, ˜80 ms push-down) are estimated to contain gas volumes (including hydrate) similar to those of conventional economic gas fields (e.g. >109 m3). It is intriguing to note that the VAMPs are predominantly located within the "donut hole" of international waters in mid-Bering Sea, beyond the present territorial limits of any nation. However, the majority of the basin could be claimed by the United States under Article 76 of the United Nations Convention on the Law of the Sea, were it ratified.

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Research paper thumbnail of A Fresh Look at the Geologic Evolution of Kingman Reef and Palmyra Atoll, U.S. Line Islands

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Research paper thumbnail of Possible deep-water gas hydrate accumulations in the Bering Sea

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Research paper thumbnail of The Effect of Plate Structure on Intraplate Volcanism, Kodiak-Bowie Seamount Chain, Gulf of Alaska

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Research paper thumbnail of Multiple melt source origin of the Line Islands (Pacific Ocean)

Geology, 2021

The Line Islands volcanic chain in the central Pacific Ocean exhibits many characteristics of a h... more The Line Islands volcanic chain in the central Pacific Ocean exhibits many characteristics of a hotspot-generated seamount chain; however, the lack of a predictable age progression has stymied previous models for the origin of this feature. We combined plate-tectonic reconstructions with seamount age dates and available geochemistry to develop a new model that involves multiple melt regions and multiple melt delivery styles to explain the spatial and temporal history of the Line Islands system. Our model identifies a new melt source region (Larson melt region at ~17°S, ~125°W) that contributed to the formation of the Line Islands, as well as the Mid-Pacific Mountains and possibly the Pukapuka Ridge.

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Research paper thumbnail of Did the Bering Sea Form as a Cenozoic Backarc Basin

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Research paper thumbnail of Scientific Oceanic Drilling (Iodp) to Test Contrasting Hypotheses for the Origin of the Aleutian Subduction Zone, Aleutian Arc, and Backarc Aleutian Basin

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Research paper thumbnail of Stratigraphic Complexity and Basement Structure in the Western Aleutian Basin of the Bering Sea

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Research paper thumbnail of Deep-Water Acoustic Anomalies from Methane Hydrate in the Bering Sea

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Research paper thumbnail of Continental margins and the U.S. extended continental shelf project

“Margins are where the action is.” With these auspicious words, the opening article of the fi rst... more “Margins are where the action is.” With these auspicious words, the opening article of the fi rst MARGINS newsletter began in spring, 1998. Now, a dozen years later, as the GeoPRISMS followon program begins, the same words resonate for studies related to the Law of the Sea Convention (LOS). The LOS is an international treaty which sets forth a comprehensive framework governing uses of the oceans. The Convention has been in effect since 1994, and there are now 157 parties to the Convention. LOS addresses many maritime issues. Just one article (Article 76) deals with the use of geological and geophysical data. Continental margins are the areas where coastal nations, using criteria established in LOS, are defining the outer limits of the region where they can exercise their exclusive rights to explore, develop, conserve, and manage the living and non-living resources of the seafl oor and sub-seafl oor. Forty-three coastal nations have proposed their outer limits since 2001 (www.un.org/Depts/los/clcs_ new/commission_submissions.htm), and another 28 have formally expressed their intention to do so (www.un.org/Depts/los/ clcs_new/commission_preliminary.htm), generating much action and interest in renewed mapping of continental margins around the globe. The process of defi ning these outer limits provides marine geoscientists excellent opportunities for collecting geological, geophysical, and hydrographic

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Long-Offset Seismic Investigations of the Deep Bering Sea

ABSTRACT

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Research paper thumbnail of Detrital Zircon Geochronology of the Bering Sea, Shelf to Deep Basin: Climatic and Eustatic Influence on Sediment Transport Pathways

Bookmarks Related papers MentionsView impact

Research paper thumbnail of The Case for Scientific Drilling in the Aleutian Basin

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Why Hydrate-linked Velocity-amplitude Anomaly Structures are Common in the Bering Sea Basin: A Hypothesis

The thick sedimentary sequence (2–12 km [6500–39,400 ft]) underlying the abyssal floors (3–4 km [... more The thick sedimentary sequence (2–12 km [6500–39,400 ft]) underlying the abyssal floors (3–4 km [9800–13,100 ft]) of the Bering Sea Basin is shallowly (360 m [1181 ft]) underlain by large (2 km [6500 ft] in diameter, 200 m [656 ft] thick) deposits of concentrated methane hydrate. Mound-shaped bodies of hydrate are displayed on seismic reflection records as velocity-amplitude anomaly (VAMP) structures imaged as velocity pull-ups overlying push-downs. The VAMPs are numerous (hundreds to thousands) and occur across an area of approximately 250,000 km2 (96,525 mi2). The abundance of VAMP structures is conjectured to be a consequence of high rates of basinwide planktonic productivity; of preservation of organic matter; biosiliceous sedimentation; of silica diagenesis; and of high heat flow; and deposition of a thick (700–1000 m [2296–3281 ft]), upper section of perhaps latest Miocene but mostly glacial-age (early Pliocene and Quaternary) turbidite beds and diatom ooze. Stacking of this upper Cenozoic sequence of water-rich beds heated underlying diatomaceous deposits of Miocene and older age and enhanced the generation of thermogenic methane and the diagenetic conversion of the opal A of porous diatom beds to the denser and contractionally fractured opal-cristobalite tridymite phase of porcellaneous shale. Silica transformation expelled large volumes of interstitial and silica-bound water that, with methane, ascended through the shale via chimneys of fracture pathways to enter the porous (60%) upper Cenozoic section of diatom ooze and turbidite beds. Ascending methane entered the hydrate stability field at approximately 360 m (1180 ft), above which concentrated deposits of methane hydrate formed as either pore-filling accumulations or more massive lenses. The deposition of high-velocity methane hydrate above a multitude of chimney structures transporting low-velocity, gas-charged fluids toward the sea floor is posited to account for the widespread recording of VAMP structures in the Bering Sea Basin.

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Research paper thumbnail of Geological and Sediment Thickness Data Sources From the U.S. Continental Margins

Although the United States has not yet ratified the United Nations Convention on the Law of the S... more Although the United States has not yet ratified the United Nations Convention on the Law of the Sea (UNCLOS), work has begun to assess the geophysical and geological data sources that might be applied to an extended continental shelf submission under Article 76 of the UNCLOS. The U.S. Geological Survey, as a follow-up to the Congressional Report published by the

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Research paper thumbnail of Aleutian basin oceanic crust

Earth and Planetary Science Letters, 2015

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Research paper thumbnail of The King Range Terrane of the Franciscan Complex, Cape Mendocino Region, Northern California: Product of Miocene and Younger Interaction of Evolving, Multi-Strand Mendocino Transform with Pacific and North American Plates

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Methane gas volume expansion ratios and ideal gas deviation factors for the deep-water Bering Sea basins

Open File Report, 2005

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Research paper thumbnail of Continental margins and the U.S. extended continental shelf project

Margins Geoprisms Newsletter, 2010

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Research paper thumbnail of Possible deep-water gas hydrate accumulations in the Bering Sea

Fire in the Ice, 2006

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Research paper thumbnail of Natural Gas and Hydrate Accumulations in the Aleutian Basin of the Bering Sea

The deep water Aleutian Basin of the Bering Sea is a major storehouse of trapped greenhouse gases... more The deep water Aleutian Basin of the Bering Sea is a major storehouse of trapped greenhouse gases. Preliminary volume estimates based on seismic reflection observations easily approach 1000 Tcf of natural gas within the basin. USGS seismic reflection data from the deep water (>3500 m) Bering Sea region include over 20,000 km of single channel profiles coincident with GLORIA sonar tracks acquired during the 1986-7 EEZscan program, plus several older multichannel lines also crossing the deep water Aleutian and Bowers Basins. These airgun-source data all provide images from seafloor to basement, over 3 km of penetration. The basin fill includes generally horizontal and uniform sedimentary reflection sequences, comprising predominantly mudstones and distal turbidites, upon oceanic crust of probable Cretaceous age. In seismic reflection images of these flat-lying sediments, methane chimneys overlain by hydrate caps stand out as distinctive velocity pseudostructures. These velocity-amplitude anomaly structures ("VAMPs") characteristically include a zone of velocity pull-up (attributed to high-seismic-velocity hydrate within the sediment) directly overlying a zone of velocity push-down (attributed to low-seismic-velocity gas in the pore spaces). A prominent hydrate bottom simulating reflection (BSR) is also present throughout the basin. Within the VAMPs, the BSR roughly separates the pull-up from the push-down. Hundreds of VAMPs have been imaged, and thousands must exist within the deep water basin. Individual examples vary widely in lateral extent, focused appearance, and amplitude effects. Some also present a seafloor manifestation of slight doming. Five example case studies are presented, focusing particularly on interval travel time anomalies and quantitative interpretation in terms of presence of hydrate and free gas. Individual large VAMPs (1-3 km across, ˜30 ms pull-up, ˜80 ms push-down) are estimated to contain gas volumes (including hydrate) similar to those of conventional economic gas fields (e.g. >109 m3). It is intriguing to note that the VAMPs are predominantly located within the "donut hole" of international waters in mid-Bering Sea, beyond the present territorial limits of any nation. However, the majority of the basin could be claimed by the United States under Article 76 of the United Nations Convention on the Law of the Sea, were it ratified.

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