The objective of this proposal is to better understand processes occurring in the early history of the Solar System (in the solar nebula as well as on planetesimals) and their chronology. To attain this objective, we will focus our investigations on radiogenic isotope systematics (the Pb-Pb absolute chronometer, and the Al-Mg and Mn-Cr short-lived chronometers), stable isotope systematics (mass-independent fractionations in a variety of elements such as Ti, Cr, Zr, and Hf) and trace element geochemistry of a variety of primitive and differentiated meteorites and their components. These objectives will be accomplished through a systematic combination of geochemical and isotopic studies, which will involve initial documentation with the SEM and electron microprobe, followed by isotope ratio measurements by one of the following means: (a) secondary ion mass spectrometry, (b) thermal ionization mass spectrometry, and (c) multicollector inductively coupled plasma mass spectrometry. Specifically, the tasks to be accomplished are as follows: 1) Comprehensive characterization (petrographic, geochemical and isotopic) and Pb-Pb chronology of a FUN (Fractionation and Unknown Nuclear) calcium-aluminum-rich inclusion (CAI) CMS-1 to constrain its formation environment and age; 2) Combined petrographic, chronologic (Pb-Pb and Al-Mg) and high precision stable isotope (including Ti, Cr, Zr and Hf) investigations of selected CAIs from relatively pristine CV3, CK3 and CR2 chondrites to determine chronology and to assess the degree of isotopic heterogeneity and stellar sources for material in the solar nebula; 3) High spatial resolution (NanoSIMS) investigations of Al-Mg systematics in Wark-Lovering (WL) rims of selected CAIs (a subset of those investigated in Task 2 above) to constrain their formation timescales; 4) Petrographic and chronologic (Pb-Pb and Al-Mg) investigations of individual chondrules from the same chondrites as those studied in Task 2 to place high resolution constraints on their formation timescales; and 5) Investigations of the petrography, trace element geochemistry and chronology (Pb-Pb, Al-Mg and Mn-Cr) of selected primitive and ungrouped achondrites to understand magmatic processes and timescales of differentiation on planetesimals in the early Solar System. The proposed research addresses the strategic science question of NASAs Emerging Worlds program (i.e., How did the Suns family of planets, satellites and minor bodies form and evolve? as per the ROSES-2014 NRA NNH14ZDA001N-EW).
|Effective start/end date||7/1/15 → 6/30/20|
- NASA: Goddard Space Flight Center: $1,953,008.00