Sr distribution as proxy for Ca distribution at depth in SXRF analysis of mm-sized carbonaceous chondrites: Implications for asteroid sample return missionsOPEN ACCESS 

· by · in , , ,

B. J. Tkalcec, P. Tack,E. De Pauw, B. Vekemans, T. Nakamura, J. Garrevoet, G. Falkenberg, L. Vincze, F. E. Brenker

MAPS
Version of Record online: 02 March 2022

LINK (OPEN ACCESS)
PDF (OPEN ACCESS)

“Reliable identification of chondrules, calcium-aluminum-rich inclusions (CAIs), carbonate grains, and Ca-phosphate grains at depth within untouched, unprepared chondritic samples by a nondestructive analytical method, such as synchrotron X-ray fluorescence (SXRF) computed tomography (CT), is an essential first step before intrusive analytical and sample preparation methods are performed. The detection of a local Ca-enrichment could indicate the presence of such a component, all of which contain Ca as major element and/or Ca-bearing minerals, allowing it to be precisely located at depth within a sample. However, the depth limitation from which Ca-K fluorescence can travel through a chondrite sample (e.g., ∼115 µm through material of 1.5 g cm−3) to XRF detectors leaves many Ca-bearing components undetected at deeper depths. In comparison, Sr-K lines travel much greater distances (∼1700 µm) through the same sample density and are, thus, detected from much greater depths. Here, we demonstrate a clear, positive, and preferential correlation between Ca and Sr and conclude that Sr-detection can be used as proxy for the presence of Ca (and, thus, Ca-bearing components) throughout mm-sized samples of carbonaceous chondritic material. This has valuable implications, especially for sample return missions from carbonaceous C-type asteroids, such as Ryugu or Bennu. Reliable localization, identification, and targeted analysis by SXRF of Ca-bearing chondrules, CAIs, and carbonates at depth within untouched, unprepared samples in the initial stages of a multianalysis investigation insures the valuable information they hold of pre- and post-accretion processes in the early solar system is neither corrupted nor destroyed in subsequent processing and analyses.”

Related posts (automatically generated):

  1. In-situ O-isotope analysis of relict spinel and forsterite in small (<200μm) Antarctic micrometeorites – samples of chondrules & CAIs from carbonaceous chondrites
  2. Signatures of the post-hydration heating of highly aqueously altered CM carbonaceous chondrites and implications for interpreting asteroid sample returnsOPEN ACCESS 
  3. Thermal metamorphism of CM chondrites: A dehydroxylation‐based peak‐temperature thermometer and implications for sample return from asteroids Ryugu and BennuOPEN ACCESS 
  4. Linking mineralogy and spectroscopy of highly aqueously altered CM and CI carbonaceous chondrites in preparation for primitive asteroid sample returnOPEN ACCESS 
  5. Timing of thermal metamorphism in CM chondrites: Implications for Ryugu and Bennu future sample returnOPEN ACCESS 
  6. The alteration history of the Jbilet Winselwan CM carbonaceous chondrite: An analog for C‐type asteroid sample returnOPEN ACCESS 
  7. The trace element composition of chondrule constituents: Implications for sample return methodologies and the chondrule silicate reservoir
  8. Origin of Al-rich chondrules in CV chondrites: Incorporation of diverse refractory components into the ferromagnesian chondrule-forming region
  9. Cr isotopes in physically separated components of the Allende CV3 and Murchison CM2 chondrites: Implications for isotopic heterogeneity in the solar nebula and parent body processesOPEN ACCESS 
  10. The chemical composition of carbonaceous chondrites: implications for volatile element depletion, complementarity and alterationOPEN ACCESS 
Tags: , , , , , , ,