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

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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.
Bidragets oversatte titelAdskillelse af fluviodeltaiske facies ud fra geokemi og tungmineraler: Et eksempel fra Miocæn i Danmark.
Udgave nummer5
Sider (fra-til)1155-1179
Antal sider25
StatusUdgivet - 2011

ID: 33980261