TY - JOUR
T1 - Palynofacies analysis and organic-walled dinoflagellate cysts as indicators of palaeo-hydrographic changes
T2 - An example from Holocene sediments in Skálafjord, Faroe Islands
AU - Roncaglia, Lucia
N1 - Funding Information:
The author acknowledges funding from the Carlsberg Foundation (Copenhagen, Denmark) as well as financial support for collection of the core from the Geological Survey of Denmark and Greenland (GEUS) and The Danish Natural Science Research Council (grant for R/V ‘Dana’ shiptime). Johnny E. Hansen (GEUS) is thanked for assistance in preparing the sample material. Ole Bennike and Antoon Kuijpers (GEUS) are thanked for their help and suggestions during the study period; Birger Larsen (GEUS) is acknowledged for providing unpublished information on Skálafjord. The AMS radiocarbon dates were performed under the supervision of Jan Heinemeier (University of Aarhus, Denmark). This paper was improved by the reviews of Jens Matthienssen (Alfred Wegener Institute, Bremerhaven, Germany) and an anonymous referee.
PY - 2004/1
Y1 - 2004/1
N2 - This study documents Holocene variations in organic matter deposition from ca. 6350 cal yr BC to AD 1430 in Skálafjord, Faroe Islands, and uses this information to assess palaeo-hydrographic conditions. The chronology of the interval studied is based on five AMS
14C ages. Based on the total sedimentary organic content, the sediments dating to ca. 6350 cal yr BC to AD 160 have been deposited under dysoxic bottom water conditions suggesting good ventilation in the water column. The sediments dating to ca. AD 160-1090 have been deposited under decreasing oxygen availability; from AD 1090 to 1430, suboxic bottom water conditions characterised the fjord. High terrestrial influx characterised most sediments in the study interval; however, moderate terrestrial influx was recorded in sediments dating to ca. 6350-5670 cal yr BC. Based on the dinoflagellate cyst assemblages, changes in the nutrient availability were inferred in the waters of the fjord over the study period. The nutrients were minimal at ca. 6350-5670 cal yr BC; they increased in the interval ca. 5670-685 cal yr BC and became very abundant at ca. 685 cal yr BC to AD 1260. A decreasing trend in nutrient availability was inferred in sediments of age ca. AD 1260-1430. A qualitative approach was used for the reconstruction of Holocene sea-surface temperature conditions based on dinoflagellate cyst and acritarch assemblages. The estimated sea-surface parameters highlighted the Mid-Holocene final stage of the Climatic Optimum (ca. 6350-5300 cal yr BC), the Neo-glaciation period (ca. 5300 cal yr BC to AD 260), a general climatic amelioration during the period ca. AD 260-1090 and a cooling at ca. AD 1090-1260.
AB - This study documents Holocene variations in organic matter deposition from ca. 6350 cal yr BC to AD 1430 in Skálafjord, Faroe Islands, and uses this information to assess palaeo-hydrographic conditions. The chronology of the interval studied is based on five AMS
14C ages. Based on the total sedimentary organic content, the sediments dating to ca. 6350 cal yr BC to AD 160 have been deposited under dysoxic bottom water conditions suggesting good ventilation in the water column. The sediments dating to ca. AD 160-1090 have been deposited under decreasing oxygen availability; from AD 1090 to 1430, suboxic bottom water conditions characterised the fjord. High terrestrial influx characterised most sediments in the study interval; however, moderate terrestrial influx was recorded in sediments dating to ca. 6350-5670 cal yr BC. Based on the dinoflagellate cyst assemblages, changes in the nutrient availability were inferred in the waters of the fjord over the study period. The nutrients were minimal at ca. 6350-5670 cal yr BC; they increased in the interval ca. 5670-685 cal yr BC and became very abundant at ca. 685 cal yr BC to AD 1260. A decreasing trend in nutrient availability was inferred in sediments of age ca. AD 1260-1430. A qualitative approach was used for the reconstruction of Holocene sea-surface temperature conditions based on dinoflagellate cyst and acritarch assemblages. The estimated sea-surface parameters highlighted the Mid-Holocene final stage of the Climatic Optimum (ca. 6350-5300 cal yr BC), the Neo-glaciation period (ca. 5300 cal yr BC to AD 260), a general climatic amelioration during the period ca. AD 260-1090 and a cooling at ca. AD 1090-1260.
KW - Dinoflagellates
KW - Faroe
KW - Holocene
KW - Hydrography
KW - North Atlantic Ocean
KW - Palynofacies
UR - http://www.scopus.com/inward/record.url?scp=1642527163&partnerID=8YFLogxK
U2 - 10.1016/S0377-8398(03)00065-3
DO - 10.1016/S0377-8398(03)00065-3
M3 - Article
SN - 0377-8398
VL - 50
SP - 21
EP - 42
JO - Marine Micropaleontology
JF - Marine Micropaleontology
IS - 1-2
ER -