Research Article| April 01, 2006 Transition from seamount chain to intraplate volcanic ridge at the East Pacific Rise Scott M. White; Scott M. White 1Department of Geological Sciences, University of South Carolina, Columbia, South Carolina 29208, USA Search for other works by this author on: GSW Google Scholar Susumu Umino; Susumu Umino 2Institute of Geosciences, Shizuoka University, Ohya 836, Shizuoka 422-8529, Japan Search for other works by this author on: GSW Google Scholar Hidenori Kumagai Hidenori Kumagai 3Institute for Frontier Research on Earth Evolution, Japan Agency for Marine Science and Technology, 2-15 Natsushima-cho, Yokosuka 237-0061, Japan Search for other works by this author on: GSW Google Scholar Author and Article Information Scott M. White 1Department of Geological Sciences, University of South Carolina, Columbia, South Carolina 29208, USA Susumu Umino 2Institute of Geosciences, Shizuoka University, Ohya 836, Shizuoka 422-8529, Japan Hidenori Kumagai 3Institute for Frontier Research on Earth Evolution, Japan Agency for Marine Science and Technology, 2-15 Natsushima-cho, Yokosuka 237-0061, Japan Publisher: Geological Society of America Received: 17 Oct 2005 Revision Received: 25 Nov 2005 Accepted: 05 Dec 2005 First Online: 09 Mar 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (2006) 34 (4): 293–296. https://doi.org/10.1130/G2234.1 Article history Received: 17 Oct 2005 Revision Received: 25 Nov 2005 Accepted: 05 Dec 2005 First Online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Scott M. White, Susumu Umino, Hidenori Kumagai; Transition from seamount chain to intraplate volcanic ridge at the East Pacific Rise. Geology 2006;; 34 (4): 293–296. doi: https://doi.org/10.1130/G2234.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract A number of large submarine intraplate volcanic ridges have been discovered throughout the South Pacific Basin, but their origins are enigmatic. Recent shipboard geophysical surveys reveal that the Sojourn Ridge, one of these large intraplate ridges, becomes a chain of discrete seamount volcanoes that intersects the ridge axis. This seamount chain exhibits several features that suggest that it is directly related to the Sojourn Ridge. The Sojourn Seamount Chain grows continuously in both volume and number of seamounts with distance from the spreading axis; several loci of recent volcanic activity along the chain are evident in the side-scan imagery, and a mantle Bouguer anomaly low underlies the entire length of the chain. This evidence provides new constraints on the origin of intraplate volcanic ridges. The continuation of the Sojourn Ridge system as a volcano chain that extends to within 5 km of the spreading axis implies active generation of magma and a focusing mechanism, such as flexural stresses induced by the mass of the volcanic pile, as the probable mechanism for developing volcanic ridges and long seamount chains. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.
The spatial variations in Quaternary sediments on the inner continental shelf are produced by the progression of depositional environments during the latest sea-level rise, and this sedimentary architecture plays a fundamental role in controlling groundwater discharge. However, coincident seismic mapping, sediment cores, and hydrological studies are rare. Here, we combine high-resolution, 0.5–10 kHz, high-frequency seismic profiles with sediment cores to examine the nature of the sediment deposits, including paleochannels, where submarine groundwater discharge has also been studied in a 150 km2 area of the inner shelf north of Charleston, South Carolina. We used high-frequency seismic reflection to interpret seismic facies boundaries, including 16 paleochannel crossings, to 20 km offshore. From 13 vibracores taken at the intersections of the seismic lines, we defined seven lithofacies representative of specific depositional environments. The paleochannels that we cored contain thick layers of structureless mud sometimes interbedded with silt, and mud is common in several of the nearshore cores. Our results indicate that paleochannels are often mud-lined or filled in this area and were most likely former estuarine channels. Neither the paleochannels nor a mud layer were found farther than 11 km off the present shoreline. This offshore distance coincides with the strongest pulses of groundwater discharge, emerging just beyond the paleochannels. This suggests that the muddy paleochannel system acts as a confining layer for submarine groundwater flow.
Processes that occur within and across the oceanic crust—in particular along mid‐ocean ridges and oceanic spreading centers—play a huge role in the dynamics of the Earth. The largest fluxes of heat and material between the Earth's mantle, crust, and seawater occur via magmatic, tectonic, and hydrothermal processes along oceanic spreading centers and their vast flanks. Roughly two thirds of the Earth's surface is accreted through magmatic and tectonic processes along mid‐ocean ridges, and subduction of this ocean crust in turn influences mantle compositions. Exchange of elements between ocean crust and seawater strongly influences seawater compositions and leaves a geologic record of fluid‐rock reactions in altered ocean crust. Some of these reactions contribute energy to microbial activity of a largely unexplored biosphere. The dynamics of ridge and ocean crustal processes therefore have enormous implications for thermal, chemical, and biological exchanges between the solid Earth and the hydrosphere.
