Santa Lucia (2008) (L6) chondrite, a recent fall: composition, noble gases, nitrogen and cosmic ray exposure age.

MAHAJAN R.; VARELA M.E.; JORON JL,

EARTH, MOON, AND PLANETS

SPRINGER

Lugar: Berlin; Año: 2015

0167-9295

The Santa Lucia (2008) - one the most recent Argentine meteorite fall, fell in San Juanprovince, Argentina, on 23 Jan. 2008. Several masses (total ~6 kg) were recovered.Most are totally covered by fusion crust. The exposed interior is of light-grey colour.Chemical data [olivine (Fa 24.4) and low-Ca pyroxene (En77.8 Fs 20.7 Wo1.6)]indicate that Santa Luica (2008) is a member of the low iron L chondrite group,corresponding to the equilibrated petrologic type 6. The meteorite name was approvedby the Nomenclature Committee (NomCom) of the Meteoritical Society (MeteoriticBulletin, no. 97). We report about the chemical composition of the major mineralphases, its bulk trace element abundance, its noble gas and nitrogen data. The cosmicray exposure (CRE) age based on cosmogenic 3He, 21Ne, and 38Ar around 20 Ma iscomparable to one peak of L chondrites. The radiogenic K-Ar age of 2.96 Ga, while theyoung U,Th-He are of 1.2 Ga indicates that Santa Lucia (2008) lost radiogenic 4Hemore recently. Low cosmogenic (22Ne/21Ne)c and absence of solar wind noble gasesare consistent with irradiation in a large body. Heavy noble gases (Ar/Kr/Xe) indicatedtrapped gases similar to ordinary chondrites. Krypton and neon indicates irradiation inlarge body, implying large pre-atmospheric meteoroid.