UNIGE document Doctoral Thesis
previous document  unige:144557  next document
add to browser collection
Title

Constraining authigenic and diagenetic processes in Fe-rich lacustrine sediments using proxies of paleoredox conditions

Author
Director
Defense Thèse de doctorat : Univ. Genève, 2020 - Sc. 5550 - 2020/06/26
Abstract Paleoclimate reconstructions using lake sediments are based on the study of climate proxies. This thesis explores the potential of Fe-minerals to record climate-driven processes and their stability throughout burial and reevaluates Rock-Eval pyrolysis to asses organic matter-related proxies, using End-Member Analysis. We described the Fe-mineral assemblage through sequential extraction in a 100 meters-long core from lake Towuti, Indonesia, and from a 40 centimeters-long core from lake Fagnano, Argentina. We investigated the coevolution of chemical and isotopic signatures (δ56Fe) in reactive ferric (Fe-(oxyhydr)oxides) and ferrous (siderite and magnetite) phases. The isotopic correlation between ferric and ferrous phases in Towuti sediments reveals slow dissolution of Fe-oxides and the formation of diagenetic siderite. The high mobility of iron during diagenesis limits its use as a proxy for water column redox conditions. These transformations can substantially occur at the redox boundary, a few centimeters below the sediment surface, as in lake Fagnano.
Identifiers
URN: urn:nbn:ch:unige-1445578
Full text
Thesis (19.4 MB) - public document Free access
Structures
Research group Limnology and Geomicrobiology
Citation
(ISO format)
ORDONEZ RENDON, Luis Gabriel. Constraining authigenic and diagenetic processes in Fe-rich lacustrine sediments using proxies of paleoredox conditions. Université de Genève. Thèse, 2020. doi: 10.13097/archive-ouverte/unige:144557 https://archive-ouverte.unige.ch/unige:144557

110 hits

6 downloads

Update

Deposited on : 2020-11-11

Export document
Format :
Citation style :