Trace elements chondrites

Hertogen J., Janssens M.-J., Takahashi H., Morgan J. W., and Anders E. (1983) Enstatite chondrites trace element clues to their origin. Geochim. Cosmochim. Acta 47, 2241-2255. 

Two recent examples of such accreted oceanic plateaus are the CCOP and the OJP. All of the lavas sampled from the OJP and most of the lavas from the CCOP are relatively homogeneous basalts with initial eNd values between +5 and +8 and broadly chondritic trace element ratios. In contrast, high-MgO lavas found in the CCOP reveal evidence of a more heterogeneous plume source region, containing both enriched (eNd <+5 (La/Nd)cn>l) and depleted (eNd < +8 (La/Nd)cn[Pg.1819]

Weber D, Zinner E, Bischoff A (1995) Trace element abundances and magnesium, calcium, and titanium isotopic compositions of grossite-containing inclusions from the carbonaceous chondrite Acfer 182. Geochim Cosmochim Acta 59 803-823... 

Krahenbuhl, U., Morgan, J. W., Ganapathy, R. and Anders, E. (1973) Abundances of 17 trace elements in carbonaceous chondrites. Geochimica et Cosmochimica Acta, 37, 1353-1370. 

As implied by their names, chondritic IDPs have roughly cosmic bulk compositions. Element ratios for hundreds of analyzed particles are roughly chondritic (data for CP IDPs are shown in Fig. 12.7) (Schramm et al., 1989). An exception, though, is carbon, which is significantly more abundant in IDPs. The mean carbon content of I DPs is 10 wt.%, relative to 3.2 wt.% for Cl chondrites (Bradley, 2004). The abundances of trace elements in bulk IDPs scatter from 0.3 to 3 times Cl, and volatile elements especially tend to be enriched (Flynn and Sutton, 1992). Higher abundances of carbon and of volatile elements, relative to the most solar-like carbonaceous chondrites, support the contention that IDPs are among the most primitive materials known. 

Flynn, G. J. and Sutton, S. R. (1992) Trace elements in chondritic stratospheric particles zinc depletion as a possible indicator of atmospheric entry heating. Proceedings of the Lunar and Planetary Science Conference, 22, 171-184. 

Another analytical procedure for sample preparation including analyte separation and enrichment is the coprecipitation of the trace elements to be determined. The co-precipitation behaviour of Ti, Mo, Sn and Sb under two different fluoride forming conditions (at < 70 °C in an ultrasonic bath and at 245 °C using a Teflon bomb) has been studied to improve the accuracy of the trace analysis of these elements in Ca-Al-Mg fluorides, by ICP-MS.14 The applicability of this analytical method (including isotope dilution technique) was demonstrated for four carbonaceous chondrites and silicate reference materials of basalt or andesite.14... 

C60 has not yet been detected in primitive meteorites, a finding that could demonstrate its existence in the early solar nebular or as a component of presolar dust. However, other allotropes of carbon, diamond and graphite, have been isolated from numerous chondritic samples. Studies of the isotopic composition and trace element content and these forms of carbon suggest that they condensed in circumstellar environments. Diamond may also have been produced in the early solar nebula and meteorite parent bodies by both low-temperature-low-pressure processes and shock events. Evidence for the occurrence of another carbon allotrope, with sp hybridized bonding, commonly known as carbyne, is presented. 

Rocholl A. and Jochum K. P. (1993) Th, U and other trace elements in carbonaceous chondrites imphcations for the terrestrial and solar system Th/U ratios. Earth. Planet. Sci. Lett. 117, 265-278. 

Paul R. L. and Lipschutz M. E. (1990) Consortium study of labile trace elements in some Antarctic carbonaceous chondrites Antarctic and non-Antarctic meteorite comparisons. Proc. NIPR Symp. Antarct. Meteorit. 3, 80-95. 

Figure 24 Concentration profiles of siderophile elements in a radially zoned Fe,Ni grain in the CBb chondrite, QUE 94411 (a) electron microprobe data (b) and (c) trace element data from laser ablation ICPMS (Campbell et ai, 2001). The nickel, cobalt, and chromium profiles can be matched by nonequilibrium nebular condensation assuming an enhanced dust-gas ratio of —36 X solar, partial condensation of chromium into silicates, and isolation of 4% of condensates per degree of cooling (Petaev etal, 2001). Concentrations of the refractory siderophile elements, osmium, iridium, platinum, ruthenium, and rhodium, are enriched at the center of the grain by factors of 2.5-3 relative to edge concentrations, which are near Cl levels after normalization to iron (reproduced by permission of University of Arizona on behalf of The Meteoritical Society from Meteorit. Planet. ScL, 2002, 37, pp. 1451-1490).

Alexander C. M. O D. (1995) Trace element contents of chondmle rims and interchondmle matrix in ordinary chondrites. Geochim. Cosmochim. Acta 59, 3247—3266. 

Brearley A. J., Bajt S., and Sutton S. (1995) Distribution of moderately volatile trace elements in fine-grained chondrule rims in the unequilibrated C03 chondrite, ALH A77307. Geochim. Cosmochim. Acta 59, 4307-4316. 

Morlok A., ElossC., Zinner E., Bischotf A., Henkel T., Rost D., Stephan T., and JessbergerE. K. (2002) Trace elements in Cl chondrites a heterogeneous distribution. In Lunar Planet. Sci. XXXIII, 1269. The Lunar and Planetary Institute, Houston (CD-ROM). 

Figure 9 A type B1 inclusion from the Allende CVS chondrite. This centimeter-sized marhle consists mainly of melilite (bluish-white), titanium-aluminum-rich calcic pyroxene (bright colors), and anorthite and spinel (not readily visible in photo). Type B1 inclusions figure prominently in the early petrologic, trace element, and isotopic studies of CAIs, in part because of the richness of information about physicochemical histories available from petrologic, chemical and isotopic properties. Ironically, because type B inclusions occur only in CVS chondrites, they are nonrepresentative of CAIs in general. Photograph taken in cross-polarized transmitted fight. The colors are not the true colors of the crystals they are artifacts of the polarized fight.

The origin of mass-dependent isotopic fractionation in FUN CAIs is commonly (and somewhat casually) assumed to be the result of Rayleigh-type distillation, while the inclusions were molten. It is true that a strong case for distillation has been made in the case of the so-called HAL-type hibonites (see Section 1.08.7), based on trace element and isotopic properties (Lee et al, 1979, 1980 Davis et al, 1982 Ireland et al, 1992 Floss et al, 1996). Such an origin is problematic for other FUN CAIs, however, especially those that are otherwise identical in bulk composition to non-FUN CAIs. Most notably this is true of the FoBs that also happen to have F or FUN properties (Clayton et al, 1984 Davis et al, 1991). These objects are magnesium-rich relative to other CAIs, yet distillation experiments conducted on chondritic starting materials consistently show that... 

The bulk trace element abundance patterns in CAIs are generally agreed to reflect element volatility, with the most refractory elements enriched relative to solar (Cl chondrite) abundances, and volatile elements depleted. 

Ireland T. R., Fahey A. J., and Zinner E. K. (1988) Trace element abundances in hibonites from the Murchison carbonaceous chondrite constraints on high-temperature processes in the solar nebula. Geochim. Cosmochim. Acta 52, 2841-2854. 

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