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Orbital forced cyclicity of reflector strength in the seismic records of the Cape Basin
Author(s) -
Weigelt Estella,
UenzelmannNeben Gabriele
Publication year - 2007
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2006gl028376
Subject(s) - geology , milankovitch cycles , eccentricity (behavior) , amplitude , reflector (photography) , structural basin , seismology , paleontology , sedimentary rock , climatology , light source , physics , optics , quantum mechanics , political science , law , glacial period
A well‐pronounced succession of continuous high‐amplitude reflectors characterises the upper acoustic units off Southwest Africa as revealed in our seismostratigraphic study. We performed spectral analyses over age‐transformed seismic traces. The results suggest a temporal regularity in the variation of reflector strength according to Milankovitch cycles since the early Pliocene. Periods of 100 kyr/cycle between 0–2 Ma correspond to eccentricity modulations. From 2–3 Ma, shorter periods close to obliquity cycles prevail, whereas in even older units periodicity increases again to 100 kyr/cycle. We propose the cyclicity of high‐amplitude reflectors is caused by orbitally driven climate variations, which modulate the sedimentary properties and with it the seismic reflectivity.