MONAZITE STANDARDS FOR IN-SITU GEOCHRONOLOGY
The principal limitation for obtaining high-precision, accurate standard-based 208Pb/232Th ages from monazite and allanite is the lack of appropriate, well-characterized reference materials. Because both monazite and allanite are compositionally variable and SIMS, LA-ICP-MS incur instrumental mass-dependent fractionation, it is essential to closely match standards with unknowns. This proposal seeks to determine isotope dilution (ID) Th-Pb ages for the Th-rich accessory minerals monazite and allanite. Th-Pb ages currently exist for only one reference material that is commonly used-'554'. Consequently, all standard-based geochronologic measurements require an assumption that Th-Pb and U-Pb ages are equivalent. This assumption is unnecessary and, in many cases, invalid. By obtaining high-precision ID Th-Pb ages for a suite of well-characterized, community-wide reference materials, this research will provide a means of independently calibrating Th-Pb ages for minerals that can be linked to fundamental tectonic processes.
Funding:
Dr. Emily Peterman (Bowdoin)
Prof. Marty Grove (Stanford)
GEOCHRONOLOGY FACILITIES AT UCSB
Geochronologic research at UCSB combines the high analytical precision of ID-TIMS with the high spatial precision of Multi-collector and Single-collector ICP instruments. UCSB capabilities include:
•MAT 261 thermal ionization mass spectrometer
•Nu-Plasma HR equipped with enhanced sensitivity interface. Equipped with full and pseudo-high resolution capability and a fixed collector array with zoom optics.
•Nu Instruments AttoM. Single collector sector-field ICP-MS with super-fast electronics, for rapid analysis of small sample volumes across the entire mass spectrum
•An Agilent 7700S Quadrupole ICPMS equipped with high sensitivity interface
• The Nu-Plasma, AttoM and Quadrupole ICPMS can be coupled to one of two Photon Machines 193nm ArF Excimer laser ablation systems
More Information on analytical facilities at UCSB is available here
Group Members
Dr. Andrew Kylander-Clark (UCSB)
Prof. Brad Hacker (UCSB)
Prof. Matt Jackson (UCSB)
Prof. Roberta Rudnick (UCSB)
In collaboration with staff at Nu Instruments and Photon Machines
Note: Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation
The principal limitation for obtaining high-precision, accurate standard-based 208Pb/232Th ages from monazite and allanite is the lack of appropriate, well-characterized reference materials. Because both monazite and allanite are compositionally variable and SIMS, LA-ICP-MS incur instrumental mass-dependent fractionation, it is essential to closely match standards with unknowns. This proposal seeks to determine isotope dilution (ID) Th-Pb ages for the Th-rich accessory minerals monazite and allanite. Th-Pb ages currently exist for only one reference material that is commonly used-'554'. Consequently, all standard-based geochronologic measurements require an assumption that Th-Pb and U-Pb ages are equivalent. This assumption is unnecessary and, in many cases, invalid. By obtaining high-precision ID Th-Pb ages for a suite of well-characterized, community-wide reference materials, this research will provide a means of independently calibrating Th-Pb ages for minerals that can be linked to fundamental tectonic processes.
Funding:
- •NSF-EAR-1050043 to J. Cottle: 05/01/11 - 04/30/13 “Collaborative Research: Improving the accuracy and precision of monazite and allanite geochronology via ID Th-Pb ages for reference materials” NSF Abstract
Dr. Emily Peterman (Bowdoin)
Prof. Marty Grove (Stanford)
GEOCHRONOLOGY FACILITIES AT UCSB
Geochronologic research at UCSB combines the high analytical precision of ID-TIMS with the high spatial precision of Multi-collector and Single-collector ICP instruments. UCSB capabilities include:
•MAT 261 thermal ionization mass spectrometer
•Nu-Plasma HR equipped with enhanced sensitivity interface. Equipped with full and pseudo-high resolution capability and a fixed collector array with zoom optics.
•Nu Instruments AttoM. Single collector sector-field ICP-MS with super-fast electronics, for rapid analysis of small sample volumes across the entire mass spectrum
•An Agilent 7700S Quadrupole ICPMS equipped with high sensitivity interface
• The Nu-Plasma, AttoM and Quadrupole ICPMS can be coupled to one of two Photon Machines 193nm ArF Excimer laser ablation systems
More Information on analytical facilities at UCSB is available here
Group Members
Dr. Andrew Kylander-Clark (UCSB)
Prof. Brad Hacker (UCSB)
Prof. Matt Jackson (UCSB)
Prof. Roberta Rudnick (UCSB)
In collaboration with staff at Nu Instruments and Photon Machines
Note: Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation