Sierra Gorda 009: A new member of the metal‐rich G chondrites grouplet

· by · in , , ,

Marina A. Ivanova, Cyril A. Lorenz, Munir Humayun, Catherine M. Corrigan, Thomas Ludwig, Mario Trieloff, Kevin Righter, Ian A. Franchi, Alexander B. Verchovsky, Ekaterina V. Korochantseva, Vladimir V. Kozlov, Svetlana N. Teplyakova, Alexander V. Korochantsev, Victor I. Grokhovsky

Meteoritics & Planetary Science
Version of Record online: 03 August 2020

LINK

“We investigated the metal‐rich chondrite Sierra Gorda (SG) 009, a member of the new G chondrite grouplet (also including NWA 5492, GRO 95551). G chondrites contain 23% metal, very reduced silicates, and rare oxidized mineral phases (Mg‐chromite, FeO‐rich pyroxene). G chondrites are not related to CH‐CB chondrites, based on bulk O, C, and N isotopic compositions, mineralogy, and geochemistry. G chondrites have no fine‐grained matrix or matrix lumps enclosing hydrated material typical for CH‐CB chondrites. G chondrites’ average metal compositions are similar to H chondrites. Siderophile and lithophile geochemistry indicates sulfidization and fractionation of the SG 009 metal and silicates, unlike NWA 5492 and GRO 95551. The G chondrites have average O isotopic compositions Δ17O>0‰ ranging between bulk enstatite (E) and ordinary (O) chondrites. An Al‐rich chondrule from SG 009 has Δ17O>0‰ indicating some heterogeneity in oxygen isotopic composition of G chondrite components. SG 009’s bulk carbon and nitrogen isotopic compositions correspond to E and O chondrites. Neon isotopic composition reflects a mixture of cosmogenic and solar components, and cosmic ray exposure age of SG 009 is typical for O, E, and R chondrites. G chondrites are closely related to O, E, and R chondrites and may represent a unique metal‐rich parent asteroid containing primitive and fractionated material from the inner solar system. Oxidizing and reducing conditions during SG 009 formation may be connected with a chemical microenvironment and possibly could indicate that G chondrites may have formed by a planetesimal collision resulting in the lack of matrix.”

Related posts (automatically generated):

  1. Properties of a New Grouplet of G Metal-Rich Chondrites
  2. Oxygen-Isotope Compositions of Chondrules in Metal-Rich Carbonaceous Chondrites Fountain Hills and Sierra Gorda 013
  3. Northwest Africa 12273: Unique Ungrouped Metal-Rich Chondrite
  4. Study of Rb-Sr and Sm-Nd Isotopic Systems in Chondrules of the Sierra Gorda 009 and 013 Chondrites and Possible Mechanisms of Their Disturbance
  5. Sierra Gorda 013: Unusual CBa-Like Metal-Rich Chondrite
  6. Heterogenity of planetesimal collisional plume probed by glass inclusions in metal globules of Sierra Gorda 013, an unusual CBa-like chondrite
  7. Petrology and geochemistry of chondrules and metal in nwa 5492 and gro 95551: a new type of metal-rich chondrite
  8. Mineralogy, Petrology, and Oxygen Isotopic Composition of Northwest Africa (NWA) 12379, a New Metal-Rich Chondrite with Affinity to Ordinary Chondrites
  9. Mineralogy, petrology, and isotopic composition of Northwest Africa 12379, metal-rich chondrite with affinity to ordinary chondrites
  10. Calcium–aluminum-rich inclusions in non-carbonaceous chondrites: Abundances, sizes, and mineralogyOPEN ACCESS 
Tags: , , , , , , , , , , , ,