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USGS2011

Building transparent data access for ocean observatories: Coordination of U.S. IOOS DMAC with NSF's OOI Cyberinfrastructure

The NOAA-led U.S. Integrated Ocean Observing System (IOOS) and the National Science Foundation's Ocean Observatories Initiative (OOI) have been collaborating since 2007 on advanced tools and technologies that ensure open access to ocean observations and models. Initial collaboration focused on serving ocean data via cloud computing-a key component of the OOI cyberinfrastructure (CI) architecture. As the OOI transitioned from planning to execution in the Fall of 2009, an OOI/IOOS team developed a customer-based "use case" to align more closely with the emerging objectives of OOI-CI team's first software release scheduled for Summer 2011 and provide a quantitative capacity for stress-testing these tools and protocols. A requirements process was initiated with coastal modelers, focusing on improved workflows to deliver ocean observation data. Accomplishments to date include the documentation and assessment of scientific workflows for two "early adopter" modeling teams from IOOS Regional partners (Rutgers-the State University of New Jersey and University of Hawaii's School of Ocean and Earth Science and Technology) to enable full understanding of data sources and needs; generation of all-inclusive lists of the data sets required and those obtainable through IOOS; a more complete understanding of areas where IOOS can expand data access capabilities to better serve the needs of the modeling community; and development of "data set agents" (software) to facilitate data acquisition from numerous data providers and conversions of the data format to the OOI-CI canonical form. ?? 2011 MTS.

Conference Paper↗

USGS1987

Multi-channel seismic imaging of a crustal magma chamber along the East Pacific Rise

A reflection observed on multi-channel seismic profiles along and across the East Pacific Rise between 8°50′ N and 13°30′ N is interpreted to arise from the top of a crustal magma chamber located 1.2–2.4 km below the sea floor. The magma chamber is quite narrow (<4 – 6 km wide), but can be traced as a nearly continuous feature for tens of kilometres along the rise axis.

Nature↗

USGS1981

Crustal processes of the Mid-Ocean Ridge

Independent geological and geophysical investigations of the Mid-Ocean Ridge system have begun to focus on the nature of the magma chamber system underlying its central axis. Thermal models predict the existence of a steady-state chamber beneath a thin crustal lid ranging in thickness from 2 to 13 kilometers. The only aspect of the system that these models fail to account for is the extremely slow spreading rates. Seismological studies reveal the existence of a low-velocity zone beneath segments of the East Pacific Rise, which is thought to correspond to a chamber system having a half-width of approximately 5 to 10 kilometers. These estimates compare favorably with those derived separately through petrological investigations of deep-sea drilling results, various sampling programs, and field and laboratory studies of ophiolites. The chamber is thought to be wing-shaped and to remain continuously open; it is thought to be fed from the center while simultaneously solidifying at the sides as spreading carries the two halves apart. Progressive fractionation occurs by crystal settling coupled with repeated replenishment and magma mixing in an open steady-state system. Near-bottom studies reveal that the zone of extrusion above the chamber is narrow, but its eruptive history is cyclic in nature, in conflict with the predictions of a steady-state model. On-bottom gravity data at 21°N on the East Pacific Rise reveal a negative gravity anomaly that may be related to the uppermost part of the chamber. The anomaly is only 2 kilometers wide and 1 kilometer below the sea floor. This feature may be associated with a short-term upper magma reservoir. The cyclic volcanic activity is directly related to the active phase of hydrothermal circulation responsible for the observed negative thermal anomaly. The volume of water associated with this circulation is equal to the entire ocean volume passing through the accretion zone approximately every 8 million years. This is about 0.5 percent of the world's rivers, but the effective transport rates of elements are comparable to those of rivers in that anomalies for individual elements are frequently between 100 and 1000 times the average river composition. The degree of subsurface dilution determines the final exit temperature and composition of the hydrothermal fluids, ranging from manganese domination at extreme dilution to iron at intermediate levels to sulfide deposition when low dilution occurs. The discovery of massive sulfide deposits on the East Pacific Rise is destined to have a profound impact on our understanding of ore-forming processes. Whether it will have any economic significance remains to be seen.

Science↗