About This Item

Share This Item

The AAPG/Datapages Combined Publications Database

AAPG Bulletin

Abstract


Volume: 50 (1966)

Issue: 3. (March)

First Page: 625

Last Page: 626

Title: Distribution of Interstitial Salts in Drill Cores from Atlantic Ocean Floor off Florida: ABSTRACT

Author(s): Frank T. Manheim

Article Type: Meeting abstract

Abstract:

Interstitial water from five Paleocene to Recent core series, taken on the J.O.I.D.E.S. offshore drilling project, has been analyzed for chloride and major cations. The cores were obtained at depths to 300 meters below the sea bottom on the continental shelf, the Florida-Hatteras slope, and the Blake plateau.

Samples from several holes show a marked downward increase in chloride concentrations, with maximum Cl- greater than 26 ^pmil, equivalent to a salinity greater than 47 ^pmil. It appears that forces

End_Page 625------------------------------

tending to concentrate brines in deeper parts of many older sedimentary basins may operate at depths of only a few hundred feet in young sediments. The downward increases in salinity can not be accounted for easily by such mechanisms as molecular filtration. However, a combination of pressure-induced diffusion and migration induced by the geothermal gradient (Soret effect) tends to pump salts downward and appears to be a promising explanation for the increase in salt content with depth.

Total water content in the cores is uneven, partly because of irregular carbonate cementation. The cementation may be related partly to changes in ionic composition noted in the interstitial waters.

Fresh waters have been detected in marine strata under the Atlantic Ocean as far as 60 miles from shore. The water-bearing zones are believed to be extensions of land aquifers and may discharge in the slope regions.

End_of_Article - Last_Page 626------------

Copyright 1997 American Association of Petroleum Geologists