The nature of varved sedimentation in the Cariaco Basin, Venezuela, and its palaeoclimatic significance

Konrad A. Hughen, Jonathan T. Overpeck, Larry C Peterson, Robert F. Anderson

Research output: Contribution to journalArticle

34 Citations (Scopus)

Abstract

A laminated sediment record of the last 12 600 radiocarbon years from the anoxic Cariaco Basin provides a rare opportunity to study interannual to millenial-scale climatic change in a marine setting. Sedimentological and radiometric analyses of laminae couplets in the basin sediments indicate that they are annually deposited varves. The varves consist of light and dark laminae which are deposited as the result of the Intertropical Convergence Zone's annual north-south migration over the tropical North Atlantic, and the impact of this migration on regional upwelling and rainfall patterns. Light laminae contain planktonic fossils (predominantly diatoms) and are an indicator of productivity over the basin during the winter-spring upwelling season. Dark laminae contain terrigenous mineral grains and are an indicator of runoff from northern South America during the late summer-fall rainy season. Varve measurements developed using X-ray images and thin sections indicate that a continuous 14 000 calendar year long varve chronology may be generated. Preliminary measurements of thickness of individual light and dark laminae for the period 12.6 to 9 ka BP show similar palaeoclimate signals. Thickness of dark laminae, interpreted as measuring changes in regional runoff, increased rapidly at 10.8 ka BP and decreased rapidly at 9.8 ka BP, an interval coincident with the Younger Dryas cold period. Thickness of light (diatom-rich) laminae, indicative of productivity and possibly upwelling intensity, also show an increase at 10.8 ka BP, and a rapid decrease at 9.8 ka BP, simultaneous with the changes in the dark laminae. Current work is focusing on building long multiple-core varve chronologies and using these for palaeoclimatic reconstructions and geochronological research.

Original languageEnglish (US)
Pages (from-to)171-183
Number of pages13
JournalGeological Society Special Publication
Volume116
DOIs
StatePublished - 1996
Externally publishedYes

Fingerprint

varve
Sedimentation
sedimentation
Runoff
upwelling
basin
Sediments
Productivity
chronology
diatom
runoff
productivity
intertropical convergence zone
Rain
Younger Dryas
Minerals
thin section
paleoclimate
sediment
X rays

ASJC Scopus subject areas

  • Ocean Engineering
  • Water Science and Technology
  • Geology

Cite this

The nature of varved sedimentation in the Cariaco Basin, Venezuela, and its palaeoclimatic significance. / Hughen, Konrad A.; Overpeck, Jonathan T.; Peterson, Larry C; Anderson, Robert F.

In: Geological Society Special Publication, Vol. 116, 1996, p. 171-183.

Research output: Contribution to journalArticle

@article{0db6e762e7c54807872fed94a2c5d110,
title = "The nature of varved sedimentation in the Cariaco Basin, Venezuela, and its palaeoclimatic significance",
abstract = "A laminated sediment record of the last 12 600 radiocarbon years from the anoxic Cariaco Basin provides a rare opportunity to study interannual to millenial-scale climatic change in a marine setting. Sedimentological and radiometric analyses of laminae couplets in the basin sediments indicate that they are annually deposited varves. The varves consist of light and dark laminae which are deposited as the result of the Intertropical Convergence Zone's annual north-south migration over the tropical North Atlantic, and the impact of this migration on regional upwelling and rainfall patterns. Light laminae contain planktonic fossils (predominantly diatoms) and are an indicator of productivity over the basin during the winter-spring upwelling season. Dark laminae contain terrigenous mineral grains and are an indicator of runoff from northern South America during the late summer-fall rainy season. Varve measurements developed using X-ray images and thin sections indicate that a continuous 14 000 calendar year long varve chronology may be generated. Preliminary measurements of thickness of individual light and dark laminae for the period 12.6 to 9 ka BP show similar palaeoclimate signals. Thickness of dark laminae, interpreted as measuring changes in regional runoff, increased rapidly at 10.8 ka BP and decreased rapidly at 9.8 ka BP, an interval coincident with the Younger Dryas cold period. Thickness of light (diatom-rich) laminae, indicative of productivity and possibly upwelling intensity, also show an increase at 10.8 ka BP, and a rapid decrease at 9.8 ka BP, simultaneous with the changes in the dark laminae. Current work is focusing on building long multiple-core varve chronologies and using these for palaeoclimatic reconstructions and geochronological research.",
author = "Hughen, {Konrad A.} and Overpeck, {Jonathan T.} and Peterson, {Larry C} and Anderson, {Robert F.}",
year = "1996",
doi = "10.1144/GSL.SP.1996.116.01.15",
language = "English (US)",
volume = "116",
pages = "171--183",
journal = "Geological Society Special Publication",
issn = "0305-8719",
publisher = "Geological Society of London",

}

TY - JOUR

T1 - The nature of varved sedimentation in the Cariaco Basin, Venezuela, and its palaeoclimatic significance

AU - Hughen, Konrad A.

AU - Overpeck, Jonathan T.

AU - Peterson, Larry C

AU - Anderson, Robert F.

PY - 1996

Y1 - 1996

N2 - A laminated sediment record of the last 12 600 radiocarbon years from the anoxic Cariaco Basin provides a rare opportunity to study interannual to millenial-scale climatic change in a marine setting. Sedimentological and radiometric analyses of laminae couplets in the basin sediments indicate that they are annually deposited varves. The varves consist of light and dark laminae which are deposited as the result of the Intertropical Convergence Zone's annual north-south migration over the tropical North Atlantic, and the impact of this migration on regional upwelling and rainfall patterns. Light laminae contain planktonic fossils (predominantly diatoms) and are an indicator of productivity over the basin during the winter-spring upwelling season. Dark laminae contain terrigenous mineral grains and are an indicator of runoff from northern South America during the late summer-fall rainy season. Varve measurements developed using X-ray images and thin sections indicate that a continuous 14 000 calendar year long varve chronology may be generated. Preliminary measurements of thickness of individual light and dark laminae for the period 12.6 to 9 ka BP show similar palaeoclimate signals. Thickness of dark laminae, interpreted as measuring changes in regional runoff, increased rapidly at 10.8 ka BP and decreased rapidly at 9.8 ka BP, an interval coincident with the Younger Dryas cold period. Thickness of light (diatom-rich) laminae, indicative of productivity and possibly upwelling intensity, also show an increase at 10.8 ka BP, and a rapid decrease at 9.8 ka BP, simultaneous with the changes in the dark laminae. Current work is focusing on building long multiple-core varve chronologies and using these for palaeoclimatic reconstructions and geochronological research.

AB - A laminated sediment record of the last 12 600 radiocarbon years from the anoxic Cariaco Basin provides a rare opportunity to study interannual to millenial-scale climatic change in a marine setting. Sedimentological and radiometric analyses of laminae couplets in the basin sediments indicate that they are annually deposited varves. The varves consist of light and dark laminae which are deposited as the result of the Intertropical Convergence Zone's annual north-south migration over the tropical North Atlantic, and the impact of this migration on regional upwelling and rainfall patterns. Light laminae contain planktonic fossils (predominantly diatoms) and are an indicator of productivity over the basin during the winter-spring upwelling season. Dark laminae contain terrigenous mineral grains and are an indicator of runoff from northern South America during the late summer-fall rainy season. Varve measurements developed using X-ray images and thin sections indicate that a continuous 14 000 calendar year long varve chronology may be generated. Preliminary measurements of thickness of individual light and dark laminae for the period 12.6 to 9 ka BP show similar palaeoclimate signals. Thickness of dark laminae, interpreted as measuring changes in regional runoff, increased rapidly at 10.8 ka BP and decreased rapidly at 9.8 ka BP, an interval coincident with the Younger Dryas cold period. Thickness of light (diatom-rich) laminae, indicative of productivity and possibly upwelling intensity, also show an increase at 10.8 ka BP, and a rapid decrease at 9.8 ka BP, simultaneous with the changes in the dark laminae. Current work is focusing on building long multiple-core varve chronologies and using these for palaeoclimatic reconstructions and geochronological research.

UR - http://www.scopus.com/inward/record.url?scp=0242528951&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0242528951&partnerID=8YFLogxK

U2 - 10.1144/GSL.SP.1996.116.01.15

DO - 10.1144/GSL.SP.1996.116.01.15

M3 - Article

VL - 116

SP - 171

EP - 183

JO - Geological Society Special Publication

JF - Geological Society Special Publication

SN - 0305-8719

ER -