1. Study Site: Shatsky Rise A large igneous province in the Equatorial Pacific
Index Tex86 =
(III+IV + VI)/(II + III + IV + VI)
proportional to temperature
Biogeochemical Profiles of Climatic and Environmental Changes Inducing Deposition of Organic-rich Sediments during the Early Aptian
Simon C. Brassell, Biogeochemical Laboratories, Department of Geological Sciences, Indiana University, Bloomington, IN
Biogeochemical data reflect environ-mental conditions providing evidence of (i) anoxia - from biomarkers, (ii) N2 fixation - from N isotopes, (iii) the abundance of cyanobacteria - from 2-Mehopanes, and (iv) sea surface temperatures - from TEX86.
The evidence that cyanobacteria increase during cooler episodes suggests that either their populations are affected by environmental conditions, or that their biochemical production of 2-Mehopanes is environmentally controlled
Early Aptian sediment core
warm
cooler
warm
cooler
warm
Shatsky Rise: West Central Pacific