TY - JOUR
T1 - Morphological and abundance variations in Homotryblium-cyst assemblages related to depositional environments¤ uppermost Oligocene-Lower Miocene, Jylland, Denmark
AU - Dybkjær, Karen
PY - 2004/4/13
Y1 - 2004/4/13
N2 - Abundant occurrences of Homotryblium
dinoflagellate cysts have been interpreted as reflecting deposition in
near-shore, marginal marine areas, either in hypersaline or low-salinity
environments. It has also been suggested that the process length of Homotryblium cysts is related to proximity to the coast.The present study provides new insights in the ecology of Homotryblium and adds important information about the use of the morphological variations of Homotryblium cysts for environmental reconstructions. It presents an example where Homotryblium
cysts show high relative abundances in a low-salinity, partly
restricted marine depositional environment. Four different species of Homotryblium were recorded. Homotryblium? additense is proposed as a new species. The regional palaeogeographic distribution of the four species: H.? additense, Homotryblium vallum, Homotryblium plectilum and Homotryblium tenuispinosum, shows a distinct depositional proximal–distal distribution pattern. H.? additense occurs only in a narrow stratigraphic interval in the most proximal part of the study area. H. vallum only occurs sporadically, mainly in the proximal parts of the study area. H. plectilum dominates the proximal areas while H. tenuispinosum
dominates the more distal areas. Variations in abundance and cyst-type
also seem to respond to systems tracts, sequence boundaries and flooding
surfaces.The observed distributional patterns of Homotryblium
species strongly indicate a response to the salinity of the
depositional environment. It is further suggested that at least some of
the recorded species of Homotryblium originated from the same
motile dinoflagellate species, producing cysts of different morphology
in response to variations in salinity, a phenomenon known from extant
dinoflagellates.
AB - Abundant occurrences of Homotryblium
dinoflagellate cysts have been interpreted as reflecting deposition in
near-shore, marginal marine areas, either in hypersaline or low-salinity
environments. It has also been suggested that the process length of Homotryblium cysts is related to proximity to the coast.The present study provides new insights in the ecology of Homotryblium and adds important information about the use of the morphological variations of Homotryblium cysts for environmental reconstructions. It presents an example where Homotryblium
cysts show high relative abundances in a low-salinity, partly
restricted marine depositional environment. Four different species of Homotryblium were recorded. Homotryblium? additense is proposed as a new species. The regional palaeogeographic distribution of the four species: H.? additense, Homotryblium vallum, Homotryblium plectilum and Homotryblium tenuispinosum, shows a distinct depositional proximal–distal distribution pattern. H.? additense occurs only in a narrow stratigraphic interval in the most proximal part of the study area. H. vallum only occurs sporadically, mainly in the proximal parts of the study area. H. plectilum dominates the proximal areas while H. tenuispinosum
dominates the more distal areas. Variations in abundance and cyst-type
also seem to respond to systems tracts, sequence boundaries and flooding
surfaces.The observed distributional patterns of Homotryblium
species strongly indicate a response to the salinity of the
depositional environment. It is further suggested that at least some of
the recorded species of Homotryblium originated from the same
motile dinoflagellate species, producing cysts of different morphology
in response to variations in salinity, a phenomenon known from extant
dinoflagellates.
KW - Biostratigraphy
KW - Denmark
KW - Dinoflagellate cysts
KW - Homotryblium
KW - Palaoeecology
KW - Palynology
KW - Upper Oligocene-Lower Miocene
UR - http://www.scopus.com/inward/record.url?scp=3543053479&partnerID=8YFLogxK
U2 - 10.1016/j.palaeo.2003.12.021
DO - 10.1016/j.palaeo.2003.12.021
M3 - Article
VL - 206
SP - 41
EP - 58
JO - Palaeogeography, Palaeoclimatology, Palaeoecology
JF - Palaeogeography, Palaeoclimatology, Palaeoecology
IS - 1-2
ER -