Seismic Stratigraphy of East Greenland
Allen Lowrie, Karl Hinz
The Neogene has two climatic signatures, based on the climate patterns of the Quaternary. The late Pleistocene, the last 800,000 years, contains 100,000-year-long glacial cycles with sea level drops from 90 to 160 m during glacial maximas. The middle Pleistocene, from approximately 2 Ma to 0.9 Ma, is composed of glacial cycles of 20,000 and of 40,000 years duration with sea level drops from 50 to 70 m. In the former case, deposition was restricted to the lower half of the shelf down to the shelfbreak and, in the latter case, to the upper and middle shelf.
This climatic model has been applied to the interpretation of a multi-channel seismic line collected by the Bundesanstalt fur Geowissenschaften und Rohstoffe on the East Greenland continental margin near 71°N. From seismic facies analysis, sigmoid reflection patterns indicate low-energy deposition along the shelfbreak; tangential oblique and complex sigmoid-oblique reflectors both indicate high-energy deposition. Sigmoid and tangential oblique reflectors suggest deposition onto the outer neritic, shelfbreak, and upper slope areas. Complex sigmoid-oblique reflectors suggest alternating prograding and aggrading on the upper and middle shelf. Thus, these various seismic facies are indicative of longterm climatic conditions. Sigmoid and tangential oblique reflectors suggest depositio during a glacial epoch, and complex sigmoid-oblique reflectors suggest deposition during an interglacial epoch.
Tentative dates for the various glacial and interglacial epochs are given here. Thus, ages and energies of deposition may be assigned to the several interpreted glacial epochal seismic sequences.
AAPG Search and Discovery Article #91043©1986 AAPG Annual Convention, Atlanta, Georgia, June 15-18, 1986.