TY - THES

T1 - A high-resolution climatic reconstruction of the paleoenvironment of Kongsfjorden trough over the past 13 000 years

AU - Ebner, Berenice

N1 - no embargo

PY - 2022

Y1 - 2022

N2 - During the CAGE 19-3 cruise with the research vessel “Kronprins Haakon” a sediment core featuring a total length of 15.24m, spanning over 13200 years BP was retrieved from the Kongsfjorden trough off NW Svalbard. Elemental-, mineralogical-, paleomagnetic- and image analyses served as multi-proxies to decipher the Holocene sedimentary paleoenvironment and its climatic variability. The core site witnessed a warm Atlantic Water inflow throughout the Holocene and was affected by meltwater processes of local tidewater glaciers. The aim of this thesis is to reconstruct the paleoproductivity and the paleoclimatic/-environmental evolution of Kongsfjorden trough during the Holocene. The Younger Dryas (YD) is characterized by cold unstable conditions and lowered productivity. A fine grained, dolomite layer between 12.4 and 12.2 ka BP was most likely deposited subglacially (basal) at the ice sheet front and transported further via turbid meltwater. The origin of this layer is probably Blomstrandhalvøya. Retreating glaciers at the end of the YD lead to plenty of nutrients boosting the productivity at the core site resulting in a high peak of phytoplankton biomarkers (HBI III) and eventually carbonate production. A two-step warming phase (Preboreal Oscillation) is interrupted by a 250-year cooling between 11.65 and 11.4ka BP. The Holocene Thermal Maximum (HTM) starts later compared to the global records since the local signal is dominated by the ongoing melting of the glaciers. The HTM between 10 and 6ka BP is characterized by high productivity triggered by strong AW advection. The gradual transition to the neoglaciation is interrupted by the Medieval Warm Period triggered by ameliorated conditions. It is proposed that the sediment source areas during the YD and early Holocene are the Krossfjorden group, Blomstrandhalvøya and Blomstrandbreen, whereas during the late Holocene Kronebreen, Kongsbreen and Kongsvegen are predominant. The paleomagnetic record indicates that the sediment core has enough remanence carrying minerals, most likely magnetite, to construct a credible inclination curve. Shallowing of the inclination is related to lithological effects and might not demonstrate true changes of the geomagnetic field. A quality data analysis showed as well that the results can be used for further paleomagnetic investigations.

AB - During the CAGE 19-3 cruise with the research vessel “Kronprins Haakon” a sediment core featuring a total length of 15.24m, spanning over 13200 years BP was retrieved from the Kongsfjorden trough off NW Svalbard. Elemental-, mineralogical-, paleomagnetic- and image analyses served as multi-proxies to decipher the Holocene sedimentary paleoenvironment and its climatic variability. The core site witnessed a warm Atlantic Water inflow throughout the Holocene and was affected by meltwater processes of local tidewater glaciers. The aim of this thesis is to reconstruct the paleoproductivity and the paleoclimatic/-environmental evolution of Kongsfjorden trough during the Holocene. The Younger Dryas (YD) is characterized by cold unstable conditions and lowered productivity. A fine grained, dolomite layer between 12.4 and 12.2 ka BP was most likely deposited subglacially (basal) at the ice sheet front and transported further via turbid meltwater. The origin of this layer is probably Blomstrandhalvøya. Retreating glaciers at the end of the YD lead to plenty of nutrients boosting the productivity at the core site resulting in a high peak of phytoplankton biomarkers (HBI III) and eventually carbonate production. A two-step warming phase (Preboreal Oscillation) is interrupted by a 250-year cooling between 11.65 and 11.4ka BP. The Holocene Thermal Maximum (HTM) starts later compared to the global records since the local signal is dominated by the ongoing melting of the glaciers. The HTM between 10 and 6ka BP is characterized by high productivity triggered by strong AW advection. The gradual transition to the neoglaciation is interrupted by the Medieval Warm Period triggered by ameliorated conditions. It is proposed that the sediment source areas during the YD and early Holocene are the Krossfjorden group, Blomstrandhalvøya and Blomstrandbreen, whereas during the late Holocene Kronebreen, Kongsbreen and Kongsvegen are predominant. The paleomagnetic record indicates that the sediment core has enough remanence carrying minerals, most likely magnetite, to construct a credible inclination curve. Shallowing of the inclination is related to lithological effects and might not demonstrate true changes of the geomagnetic field. A quality data analysis showed as well that the results can be used for further paleomagnetic investigations.

KW - Kongsfjorden

KW - Paläomagnetik

KW - Klima

KW - Paläoproduktivität

KW - Holozän

KW - Kongsfjorden trough

KW - paleoproductivity

KW - paleoenvironment

KW - Younger Dryas

KW - Neoglacial

KW - sediment provenance

KW - paleomagnetism

M3 - Master's Thesis

ER -