Project

Back to overview

Isotope geochemistry and questions of the early atmosphere, nuclear waste disposal, paleoclimate and hominin evolution

English title Isotope geochemistry and questions of the early atmosphere, nuclear waste disposal, paleoclimate and hominin evolution
Applicant Kramers Jan
Number 105505
Funding scheme Project funding (Div. I-III)
Research institution Institut für Geologie Universität Bern
Institution of higher education University of Berne - BE
Main discipline Geochemistry
Start/End 01.10.2004 - 30.09.2006
Approved amount 372'408.00
Show all

Keywords (12)

NUCLEAR WASTE DISPOSAL; CONTINENTAL CRUST FORMATI; QUATERNARY DATING; PALEOCLIMATE; ATMOSPHERIC OXYGEN; ROCK-WATER INTERACTION; Atmosphere evolution; Mo isotopes; U series; Opalinus Clay; Speleothems; U-Pb dating

Lay Summary (English)

Lead
Lay summary
A) Molybdenum in sediments as an indicator of marine redox conditions inthe geological past. It was found that strong molybdenum fractionation(up to c. 1 o/oo per mass unit) occurs in the modern marine environment,but this is not seen in Archean sediments. Consideration of possiblecauses for the fractionation make plausible that it can only occur if Mois in the hexavalent state, which would explain the unfractionated Mo inArchean sediments. This project focuses on a detailed Mo study of blackshales through the entire stratigraphy of the early Proterozoic TransvaalSupergroup (2.67 - 2.1 Ga), using Mo fractionation as a proxy foroxygenated conditions, which are thought to have started on Earthsomewhere within this period.B) Studies of 230Th/234U/238U systematics in Opalinus Clay. The theme is adetailed study of 230Th-234U-238U systematics in two natural laboratoriesof rock-water interaction: (1) rock samples and groundwater of boreholeBenken, Zürich Weinland (quasi-steady-state rock-water interaction withold, reducing groundwater), (2) similar samples from the section of MontTerri, Jura (quasi-steady-state, but modern, oxidising groundwater). Theaim of this PhD theme is to use the mobile U isotopes as natural tracersthat can be analogues for mobile actinide species in a nuclear wasterepository. The project includes analytical work and forward modelling.C) 234U/238U and U-Pb systematics and the problem of dating cave depositsolder than 500 ka. Absolute dating of cave deposits beyond the reach ofthe 230Th/234U dating method is very problematic, yet cave deposits ofsuch great age are common and contain both paleoclimatic archives, and fossils important for Hominin evolution. In this project the feasibility ofU-Pb dating for stalagmites and of combined 234U/238U dating ofspeleothems and tooth enamel is to be explored further in case studiesrelating to paleoclimatology (a stalagmite from Yemen) and to earlyhominin fossil sites in South Africa. Work on 234U/238U ratios in soilsfrom different climate zones and weathering rates will be included toprovide a basis for the cave deposit studies.
Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants

Employees

Associated projects

Number Title Start Funding scheme
113658 Isotope geochemical applications in paleooceanography, environmental sciences, paleoanthropology and paleoclimatology 01.10.2006 Project funding (Div. I-III)
68189 Isotopes, Archean continent formation and erosion , oxygenation of the atmosphere, rock-water interaction and present day weathering 01.10.2002 Project funding (Div. I-III)
128713 Acquisition of a new generation multicollector thermal ionisation mass spectrometer for geochemical and cosmochemical studies 01.01.2010 R'EQUIP

-