|Paper No. 159-0|
|FROM SAPROPEL TO RED MARL–ORBITALLY DRIVEN BEHAVIOR OF A CRETACEOUS SEA|
FISCHER, Alfred G. and GRIPPO, Alessandro, Department of Earth Sciences, Univ of Southern California, Los Angeles, CA 90089-0740, firstname.lastname@example.org|
Albian deep-water sedimentation in the Umbria-Marche facies of Italy (Mediterranean Tethys) shows complex rhythmic interbedding. Throughout Albian time the 20-ka precession drove cycles in primary productivity which resulted in marl-limestone couplets, of which the limestones, peaks in coccolith productivity, signal less fertile blue-water times. Eccentricity highs in the 95 ka short eccentricity cycle brought monsoonal regimes, upwelling, eutrophy, and bottom stagnation, punctuating the record with cm-scale sapropels. Prolonged eccentricity lows in parts of the long (406 ka) eccentricity rhythm brought dominance of zonally-driven warm, saline, nutrient-depleted waters and downwelling, resulting in episodes of red marl or red clay deposition. Episodes of strong obliquity forcing inserted additional sapropels. These sapropels are markedly distinct from the 300-ka episode of anoxia that produced oceanic anoxic event OAE 1b (the Urbino member).
GSA Annual Meeting, November 5-8, 2001
General Information for this Meeting
|Session No. 159|
Hynes Convention Center: 103
8:15 AM-12:00 PM, Thursday, November 8, 2001
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