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Research Activities 2006

Earth Chemistry

 

Click on the links below to read the 2006 Earth Chemistry research highlights Or download the 2006 Earth Chemistry Research Highlights in PDF format HERE 882 Kb

Introduction

The chemistry and isotope chemistry of natural materials is highly indicative of provenance and process throughout geological history. Our studies range in time from the earliest solar system through to processes that are actively taking place today, and in scope from planetary systems to individual molecules.

Most of our analytical work involves detailed analysis on the microscale, or concentrating trace elements from larger samples for high precision analysis. Isotopic systems can reveal both the nature of the processes involved (stable isotopes) as well as the timing of events (radiogenic isotopes), while chemical abundances can reflect protolith contributions and processes affecting various systems including biologic systems. As revealed in this year's research contributions, analytical work can be applied to topics in tectonics, ore genesis, metamorphic petrology, paleoclimate, paleoecology and regolith dating.

Geobiology

A new direction in Earth Chemistry is the study of organic matter and biomarker molecules extracted from sedimentary rocks by Dr Jochen Brocks. Biomarkers give information about ancient microbial ecosystems and their environments. Earth Chemistry and RSES have committed to a new laboratory facility for biomarker research including a new mass spectrometer. We were able to secure central support for the construction of a new laboratory and construction started on 21 November and will be completed by end-February 2007.

SHRIMP

This year has seen systematic improvements in our abilities to measure stable isotope ratios with SHRIMP II in negative ion mode. A combination of terrestrial-magnetic-field suppression, mount redesign, and suppression of secondary ions induced by the electron gun, had all contributed to pulling analytical errors well into the subpermil range. SHRIMP I has had a computer refit, even though the 14-year-old Apple Mac II has performed flawlessly, and a stage drive upgrade such that stage positions can be computer controlled. This allows unattended computer-controlled analyses. SHRIMP SI progresses with the ordering of many of the major components and final designs for most assemblies being carried out or completed.

Personnel

This year we welcome APF Fellow Dr Ian Buick who has moved from Monash University to continue his studies in combinations of metamorphic petrology, conventional light isotope geochemistry of carbonates (O-C) and silicate (O) rocks, U-Pb geochronology and mineral-scale trace element geochemistry.
Dr Yuri Amelin of the Canadian Geological Survey, Ottawa , has accepted a position funded by the Planetary Science Institute and is expected to arrive in early 2007. Dr Amelin's specialty is high precision geochronology, focusing on the earliest chronology of the solar system.

ARC and MEC

This year saw one ARC Discovery awarded to Dr Jochen Brocks for research into saline Lake Tyrrell mud. Further in this research, an ANU / U.C. Berkeley / Macquarie University collaboration in the Lake Tyrrell Metagenome/Biomarker project was successful with the award of US$1,920,911 from NSF to our collaborator Prof Jill Banfield (UC Berkeley) for the genome sequencing part of the project. Dr Masahiko Honda and collaborators were successful in securing ARC and MEC funding for a multicollector noble gas mass spectrometer, and Dr Jochen Brocks received MEC funding for an automated solvent extraction system.

Research Highlights

Geochronology and Ti-thermometry of eastern Himalayan granitoids Amos B. Aikman
Opening the possibility of more multiple analytical techniques on individual zircon grains: case study of U/Pb and (U+Th)/He dating, so called “double-dating” C.M. Allen
Signatures of extinct nuclides preserved in Earth's oldest (> 3600 Ma) rocks shed light on the “dark ages” of early planetary history Vickie C. Bennett
Ancient steroids and the evolution of complex life Jochen J. Brocks
Ar diffusion in muscovite Julien Célérier
Some insights into the SHRIMP U–Pb analysis of xenotime Andrew Cross
How chalcophile is Re? An experimental study of the solubility of Re in sulphide mattes. Raúl O. C. Fonseca
Exploring the potential of allanite as a geochronometer of high-grade crustal processes Courtney J. Gregory
Redesign of SHRIMP mounts to minimize geometric effects on isotopic and inter-elemental fractionation. Joe M. Hiess
Cosmogenic 21 Ne exposure dating of young basaltic lava flows from the Newer Volcanic Province, southwestern Victoria, Australia M. Honda
Electron-Induced Secondary Ion Emission (EISIE): An important consideration in the analysis of light isotopes in insulators Ryan Ickert
Solar Wind Oxygen in Lunar Metal Grains Trevor Ireland
Complex histories of melt inclusions in archean komatiites Antti Kallio
Extrasolar Planets and the Dry Brown Dwarf Desert Charles H. Lineweaver
What happens to zircon during subduction? Daniela Rubatto
Marginal Basin Development in the Svecofennian orogenic province 2.30 to 1.85 billion years ago R.W. Roye Rutland
The Geology, Geochemistry and Geochronology of the El Abra Mine, Chile, and the adjacent Pajonal-El Abra suite of intrusions Dianne L. Valente
Further advances in measuring the oxygen isotopic compositions of granite zircon using SHRIMP II Ian Williams