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An association of benthic foraminifera and gypsum in Holocene sediments of estuarine Chesapeake Bay, USA

Holocene

By:
and
DOI: 10.1191/0959683604hl738rr

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Abstract

Two cores of Holocene sediments recovered from the Cape Charles Channel of Chesapeake Bay yielded radiocarbon ages of about 6.8 to 5.8 ka for the lower intervals. Fossil foraminifera preserved in these lower sediments are dominated by species of Elphidium, which make up about 90% of the assemblage throughout, and probably signify deposition in hypersaline waters. Buccella frigida and Ammonia beccarii are the only other species commonly present. Hypersalinity of bottom waters seems to have been maintained by water-density stratification in a basin-like section of the channel. In core PTXT-4-P-1 transition to modern Chesapeake conditions, in which numbers of Ammonia beccarii exceed those of Elphidium, commenced about 400 years ago. In core PTXT-3-P-2 hypersalinity is further signified by the presence of abundant euhedral crystals of gypsum in association with the fossil Elphidium. This occurrence of gypsum is not attributed to palaeoclimatic aridity, but rather to inflow of groundwater from adjacent gypsiferous Miocene strata. The study shows that in palaeoclimatic investigations the significance of the presence of gypsum should be evaluated with caution - it does not necessarily signify an evaporative regime.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
An association of benthic foraminifera and gypsum in Holocene sediments of estuarine Chesapeake Bay, USA
Series title:
Holocene
DOI:
10.1191/0959683604hl738rr
Volume
14
Issue:
4
Year Published:
2004
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Holocene
First page:
614
Last page:
620
Number of Pages:
7