TY - JOUR

T1 - Distinguishing fluvio-deltaic facies by bulk geochemistry and heavy minerals: an example from the Miocene of Denmark

AU - Olivarius, Mette

AU - Rasmussen, Erik S.

AU - Siersma, Volkert Dirk

AU - Knudsen, Christian

AU - Pedersen, Gunver Krarup

PY - 2011

Y1 - 2011

N2 - Interpretations of seismic profiles, gamma-ray logs and sediment descriptions were used to classify seven facies in Miocene fluvio-deltaic deposits ofDenmark. An impartial approach was adopted by not including analytical data in the facies definition. This approach allowed identification of significant differences between facies, where each fluvio-deltaic facies can be distinguished by integrating geochemistry and mineralogy through a sedimentary succession. Variations in the heavy mineral assemblage between facies are caused primarily by sorting of hydraulically equivalent grains. Decreasing grain size of quartz and heavy minerals from the channel facies towards the delta shoreface facies and further along the coast to the spit shoreface facies is associated with an increase in sorting and textural maturity. This trend is related to longshore drift. Increasing heavy mineral grain size is found from the delta slope facies offshore to the delta toe and shelf facies. This trend is interpreted as a result of sorting by turbidity currents. The mixed origin of the transgressive lag facies is shown by the poorer sorting in this facies. By indicating the amount of alteration the sediments have been exposed to, the Ti-mineral maturity has proven useful in characterizing the facies. This systematic approach of tying depositional environments to a well-calibrated sequence stratigraphic model has generated analytical results which are valid as reference levels for future facies identifications.

AB - Interpretations of seismic profiles, gamma-ray logs and sediment descriptions were used to classify seven facies in Miocene fluvio-deltaic deposits ofDenmark. An impartial approach was adopted by not including analytical data in the facies definition. This approach allowed identification of significant differences between facies, where each fluvio-deltaic facies can be distinguished by integrating geochemistry and mineralogy through a sedimentary succession. Variations in the heavy mineral assemblage between facies are caused primarily by sorting of hydraulically equivalent grains. Decreasing grain size of quartz and heavy minerals from the channel facies towards the delta shoreface facies and further along the coast to the spit shoreface facies is associated with an increase in sorting and textural maturity. This trend is related to longshore drift. Increasing heavy mineral grain size is found from the delta slope facies offshore to the delta toe and shelf facies. This trend is interpreted as a result of sorting by turbidity currents. The mixed origin of the transgressive lag facies is shown by the poorer sorting in this facies. By indicating the amount of alteration the sediments have been exposed to, the Ti-mineral maturity has proven useful in characterizing the facies. This systematic approach of tying depositional environments to a well-calibrated sequence stratigraphic model has generated analytical results which are valid as reference levels for future facies identifications.

KW - Faculty of Science

KW - Geologi, sedimentologi

U2 - 10.1111/j.1365-3091.2010.01199.x

DO - 10.1111/j.1365-3091.2010.01199.x

M3 - Journal article

VL - 58

SP - 1155

EP - 1179

JO - Sedimentology

JF - Sedimentology

SN - 0037-0746

IS - 5

ER -