Isotope geochemistry and biomarkers in modern analogues of early Earth systems: environmental constraints and ecology of phototrophic sulfur bacteria

• Grant number: 16/15108-0
• Support Opportunities: Scholarships abroad - Research Internship - Post-doctor
• Start date: January 01, 2017
• End date: December 31, 2017
• Field of knowledge: Physical Sciences and Mathematics - Geosciences - Geology
• Principal Investigator: Elson Paiva de Oliveira
• Grantee: Alice Bosco Santos
• Supervisor: William Patrick Gilhooly Iii
• Host Institution: Instituto de Geociências (IG). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil
• Institution abroad: Indiana University-Purdue University Indianapolis, United States
• Associated to the scholarship: 16/02933-2 - Isotope geochemistry and biomarkers in Archaean terranes and in their modern analogues systems: environmental constraints and ecology of early Earth life, BP.PD

Abstract

This proposal intends to study the water columns and sediments of two shallow sulfidic lakes (Mahoney Lake in British Columbia, Canada, and Lime Blue Lake in Washington, USA), in order to better correlate environmental constraints and the ecology of phototrophic sulfur bacteria with the molecular biomarkers preserved in the sediments. The overarching hypothesis is that constraining the environmental conditions of modern meromictic lakes in which phototrophic sulfur bacteria live will greatly improve the interpretive power of the biomarkers thought indicative of photic zone euxinia (PZE) in the geologic record. The environmental niche of PZE provides evidence for paleo-depth, and paleo-productivity within ancient aquatic environments and their current proxies are organic biomarkers (okenone and isorenieratene) from two respective groups of photoautotrophic bacteria, the green sulfur bacteria (GSB) and the purple sulfur bacteria (PSB). However, ecological conditions that promote the growth and the spatial distribution of these microbial communities in modern water columns, as well as their signatures left in sediments, are still important issues that lack consensus in the scientific community. Filling these gaps will greatly improve the interpretive power of the geologic record of euxinia, especially, with respect to direct correlation between biomarkers and the depth of PZE. This investigation will be conducted using a combination of biogeochemical and molecular ecological techniques, that combined will be used to reevaluate their utility as indicators of PZE depth in geological records from ancient shale.