Very-low-temperature hydrothermal alteration of the oceanic crust and the problem of fluxes of potassium and magnesium

Online Access: Get full text
doi: 10.1029/ME002p0369
Author(s): Donnelly, T. W.; Thompson, G.; Robinson, P. T.
Author Affiliation(s): Primary:
Univ. N.Y., Dep. Geol. Sci., Binghamton, N.Y., United States
Volume Title: Deep drilling results in the Atlantic Ocean; ocean crust
Volume Author(s): Talwani, M., editor; Harrison, C. G.; Hayes, D. E.
Source: Maurice Ewing Series, 2, p.369-382; Deep drilling results in the Atlantic Ocean; ocean crust, Harriman, N.Y., March 19-25, 1978, edited by M. Talwani, C. G. Harrison and D. E. Hayes. Publisher: American Geophysical Union, Washington, DC, United States. ISSN: 0197-6346. ISBN: 978-1-118-66623-4 CODEN: MEWSDN
Note: In English. 36 refs.; illus. incl. tables
Summary: A 200 m section of drilled basalt in the Cretaceous basement of the western North Atlantic (hole 417A, Deep Sea Drilling Project) recovered the most altered basalt found to date in the world ocean. The very high uptake of potassium (690 g/cm2 for the 200 m thickness) requires the passage of very large volumes of sea water through the rock. The mineralogy of the rocks (k-feldspar, celadonite, smectite, zeolites) suggests very low temperatures, and we conclude that the water of alteration was the effluent warm water discharging from a cell of convecting water in the cooling oceanic crust. The character of the rocks and the absence of much of the earlier sediment support this idea. The principal implication of this discovery is that only a small fraction of oceanic floor altering in this way could account for the excess of potassium inferred to be entering the oceans over that accounted for in oceanic sedimentation. A further implication is that the direction of both potassium and magnesium fluxes is opposite to that inferred for higher temperatures of alteration. Abstract Copyright 1979 by the American Geophysical Union.
Year of Publication: 1979
Research Program: DSDP Deep Sea Drilling Project
Key Words: 05 Petrology, Igneous and Metamorphic; Alkali metals; Alkaline earth metals; Alteration; Atlantic Ocean; Basalts; Basement; Chemical composition; Composition; Cretaceous; Crust; Deep Sea Drilling Project; Flux; Geochemistry; Hydrothermal alteration; Hydrothermal processes; Igneous rocks; Lava; Magnesium; Marine geology; Mesozoic; Metals; Metamorphic rocks; Metasomatic rocks; Metasomatism; Ocean floors; Oceanography; Petrology; Pillow lava; Plate tectonics; Potassium; Processes; Stratigraphy; Structural geology; Structure; Temperature; Volcanic rocks
Record ID: 1980017796
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute.

Similar Items