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6. Glacial cycles drive variations in the production of oceanic crust

Author

Crowley, John W., Katz, Richard F., Huybers, Peter J., Langmuir, Charles H., and Park, Sung-Hyun

Subjects
Physics - Geophysics
Abstract

Glacial cycles redistribute water between oceans and continents causing pressure changes in the upper mantle, with consequences for melting of Earth's interior. Using Plio-Pleistocene sea-level variations as a forcing function, theoretical models of mid-ocean ridge dynamics that include melt transport predict temporal variations in crustal thickness of hundreds of meters. New bathymetry from the Australian-Antarctic ridge shows significant spectral energy near the Milankovitch periods of 23, 41, and 100 ky, consistent with model predictions. These results suggest that abyssal hills, one of the most common bathymetric features on Earth, record the magmatic response to changes in sea level. The models and data support a link between glacial cycles at the surface and mantle melting at depth, recorded in the bathymetric fabric of the sea floor., Comment: 30 pages, 6 figures (including supplementary information). Resubmitted to Science on 12 December 2014

Published
2014
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8. Mid-Ocean Ridge Basalts (MORB)

Author

Langmuir, Charles H., White, William M., editor, Casey, William H., Associate Editor, Marty, Bernhard, Associate Editor, and Yurimoto, Hisayoshi, Associate Editor

Published
2018
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33. Cross-Validation.

Author

Psychological Corp., New York, NY. and Langmuir, Charles R.

Abstract

Cross-validation in relation to choosing the best tests and selecting the best items in tests is discussed. Cross-validation demonstrated whether a decision derived from one set of data is truly effective when this decision is applied to another independent, but relevant, sample of people. Cross-validation is particularly important after statistical data have been used to choose the best tests to make up a battery for use with the next group of people. A cross-validation experiment on a new group will tell how good the choice of test really is. Item analysis is a means of improving tests. The data from the analysis are used to eliminate doubtful items and to determine the best scoring weights. By applying the revised test to a new independent group, the inventory is refined. When the test is, without change, administered to an entirely new and independent set of criterion groups, cross validation data are obtained. (For related document, see TM 002 947.) (DB)

Published
1954

38. News and Notes

Author

Lewin, William, Roberts, H. D., Boykin, Eleanor, Lehmann, Paul W., and Langmuir, Charles R.

Published
1934

42. Origin of a 'Southern Hemisphere' geochemical signature in the Arctic upper mantle

Author

Goldstein, Steven L., Soffer, Gad, Langmuir, Charles H., Lehnert, Kerstin A., Graham, David W., and Michael, Peter J.

Subjects
Mid-ocean ridges -- Chemical properties, Sea-floor spreading -- Chemical properties, Tectonics (Geology) -- Chemical properties, Earth -- Mantle, Environmental issues, Science and technology, Zoology and wildlife conservation, Chemical properties
Abstract

The Gakkel ridge, which extends under the Arctic ice cap for ~1,800km, is the slowest spreading ocean ridge on Earth. Its spreading created the Eurasian basin, which is isolated from [...]

Published
2008
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43. Hydrothermal exploration with the Autonomous Benthic Explorer

Author

German, Christopher R., Yoerger, Dana R., Jakuba, Michael, Shank, Timothy M., Langmuir, Charles H., and Nakamura, Ko-Ichi

Subjects
Plumes (Fluid dynamics), Hydrothermal systems (Geology), Ocean bottom, Earth sciences
Abstract

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.dsr.2007.11.004 Byline: Christopher R. German (a), Dana R. Yoerger (a), Michael Jakuba (a), Timothy M. Shank (a), Charles H. Langmuir (b), Ko-ichi Nakamura (c) Keywords: ABE; AUV; Hydrothermal; Exploration Abstract: We describe a three-phase use of the Woods Hole Oceanographic Institution's Autonomous Benthic Explorer (ABE), to locate, map and photograph previously undiscovered fields of high temperature submarine hydrothermal vents. Our approach represents both a complement to and a significant advance beyond the prior state of the art. Previously, hydrothermal exploration relied upon deep-tow instruments equipped with sensors that could locate sites of active 'black smoker' venting to within a few kilometers. Follow-on CTD tow-yos could then resolve the sites of seafloor venting to length scales of less than a kilometer but rarely to better than a few hundreds of meters. In our new approach ABE: (i) uses sensors to locate the center of a dispersing non-buoyant hydrothermal plume 100-400m above the seabed; (ii) makes high-resolution maps of the seafloor beneath the plume center whilst simultaneously detecting interception of any rising, buoyant hydrothermal plumes; and (iii) dives to the seafloor to take photographs in and around any new vent site to characterize its geologic setting and reveal the nature of any chemosynthetic ecosystems it may host. By conducting all of the above under long-baseline navigation, precise sites of venting can be determined to within 5m. Our approach can be used both to address important scientific issues in their own right and to ensure much more efficient use of other deep-submergence assets such as human occupied vehicles (HOVs) and remotely operated vehicles (ROVs) during follow-on studies. Author Affiliation: (a) WHOI, Woods Hole, MA 02543, USA (b) Harvard University, Cambridge, MA 02138, USA (c) AIST, Tsukuba, Ibaraki 305-8567, Japan Article History: Received 29 July 2007; Revised 7 November 2007; Accepted 12 November 2007

Published
2008

44. The spatial footprint of hydrothermal scavenging on ²³⁰Th_(XS)-derived mass accumulation rates

Author

Middleton, Jennifer L., Mukhopadhyay, Sujoy, Costa, Kassandra M., Pavia, Frank J., Winckler, Gisela, McManus, Jerry F., D'Almeida, Marcelle, Langmuir, Charles H., and Huybers, Peter J.

Abstract

Mid-ocean ridges are valuable archives of sedimentary flux records used to investigate atmospheric, oceanographic, and solid Earth responses to climate variability. Constant flux proxies, such as extraterrestrial helium-3 (³He_(ET)) and excess thorium-230 (²³⁰Th_(XS)), constrain vertical mass accumulation rates independent of the biases associated with lateral sediment transport and age model resolution. However, thorium scavenging by hydrothermal particles can perturb local ²³⁰Th_(XS) deposition and complicate its application as a constant flux proxy in near-ridge environments. We characterize the footprint of hydrothermal scavenging on sedimentary ²³⁰Th_(XS) using coupled ³He_(ET)-²³⁰Th_(XS) analyses in cores from the Mid-Atlantic Ridge and the Juan de Fuca Ridge. Samples deposited >10 km from the Juan de Fuca Ridge indicate reliable off-axis behavior of both constant flux proxies. In contrast, samples deposited

Published
2020

48. Recycled dehydrated lithosphere observed in plume-influenced mid-ocean-ridge basalt

Author

Dixon, Jacqueline Eaby, Leist, Loretta, Langmuir, Charles, and Schilling, Jean-Guy

Subjects
Environmental issues, Science and technology, Zoology and wildlife conservation
Abstract

Author(s): Jacqueline Eaby Dixon (corresponding author) [1]; Loretta Leist [1]; Charles Langmuir [2]; Jean-Guy Schilling [3] Quantifying the Earth's global geochemical water cycle is important for modelling physical properties of [...]

Published
2002
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49. Vapour undersaturation in primitive mid-ocean-ridge basalt and the volatile content of Earth's upper mantle

Author

Saal, Alberto E., Hauri, Erik H., Langmuir, Charles H., and Perfit, Michael R.

Subjects
Environmental issues, Science and technology, Zoology and wildlife conservation
Abstract

Author(s): Alberto E. Saal (corresponding author) [1]; Erik H. Hauri [2]; Charles H. Langmuir [1]; Michael R. Perfit [3] Studies of volatile elements in magmatic systems have particular importance, because [...]

Published
2002
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