Core from Cretaceous Basalt, Central Equatorial Pacific, Leg 16, Deep Sea Drilling Project

Abstract

Research Article| March 01, 1973 Core from Cretaceous Basalt, Central Equatorial Pacific, Leg 16, Deep Sea Drilling Project ROBERT S. YEATS; ROBERT S. YEATS 1Department of Geology, Ohio University, Athens, Ohio 45701 Search for other works by this author on: GSW Google Scholar WARREN C. FORBES; WARREN C. FORBES 2Department of Geological Sciences, University of Illinois at Chicago Circle, Chicago, Illinois 60680 Search for other works by this author on: GSW Google Scholar KENNETH F. SCHEIDEGGER; KENNETH F. SCHEIDEGGER 3School of Oceanography, Oregon State University, Corvallis, Oregon 97331 Search for other works by this author on: GSW Google Scholar G. ROSS HEATH; G. ROSS HEATH 3School of Oceanography, Oregon State University, Corvallis, Oregon 97331 Search for other works by this author on: GSW Google Scholar TJ. H. van ANDEL TJ. H. van ANDEL 3School of Oceanography, Oregon State University, Corvallis, Oregon 97331 Search for other works by this author on: GSW Google Scholar GSA Bulletin (1973) 84 (3): 871–882. https://doi.org/10.1130/0016-7606(1973)84<871:CFCBCE>2.0.CO;2 Article history first online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation ROBERT S. YEATS, WARREN C. FORBES, KENNETH F. SCHEIDEGGER, G. ROSS HEATH, TJ. H. van ANDEL; Core from Cretaceous Basalt, Central Equatorial Pacific, Leg 16, Deep Sea Drilling Project. GSA Bulletin 1973;; 84 (3): 871–882. doi: https://doi.org/10.1130/0016-7606(1973)84<871:CFCBCE>2.0.CO;2 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 SocietyGSA Bulletin Search Advanced Search Abstract Basalt underlying early Campanian chalk at Deep Sea Drilling Project (DSDP) Site 163 is divided into seven extrusive cooling units bounded by glassy margins. The margins have dips of 15° to 70°, suggestive of pillow flows rather than tabular flows. The margins are fresh sideromelane (glass) grading inward to opaque and reddish-brown globules containing microcrystalline material with radial, undulose extinction. Relative to adjacent sideromelane, the reddish-brown globules are enriched in sodium and calcium, whereas the opaque globules are depleted in these elements and enriched in iron and magnesium. It appears that basalt just inside the pillow margins has differentiated in place into globules of two distinct compositions. This globule zone grades inward to less rapidly cooled pyroxene varioles and intergrowths of plagioclase and opaque minerals. In the center of the thicker cooling units, the texture is diabasic. Alteration and calcite vein abundance are greatest at pillow margins and decrease inward; the interior of the thickest cooling unit is only slightly altered, and calcite veins are absent.Chemical analysis of whole rock by atomic absorption spectrophotometry, and of sideromelane by electron microprobe, indicates that the rock is a slightly weathered tholeiite. The atomic absorption analyses, except the one nearest the top of the basalt, are relatively uniform and similar to the sideromelane microprobe analyses, including those near the top of the basalt. This suggests that deep penetration is not necessary to get through the severely altered layer at the basalt surface, and that within this altered layer, analyses of sideromelane may be more representative of crustal composition than analyses of whole rock. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.