Elemental abundances chondrites

The historical background is presented for the asteroid-impact theory that is based on the iridium anomaly found in rocks frm the Cretaceous-Tertiary boundary. Recent measurements of Ir, Pt, and Au abundances from such rocks in Denmark have shown that the element abundance ratios are different from mantle-derived sources and agree with values for chondritic meteorites within one standard deviation of the measurement errors (7-10%). Rare-earth patterns for these rocks are... 

Each abundance was divided by the abundance of that element (except for Rh) in Type / carbonaceous chondrites. Rh abundances were divided by Rh abundances in other types of chondrites as Cl values were not available. Errors in the LBL measurements reflect 1 a values of the counting errors, except for the Au error. The latter is the root-mean-square deviation of six measurements, because the six values were not consistent within counting errors. The Os measurement was on a HNO,-insoluble residue that had been fired to 800°C. Key , this work and O, previous work of Ganapathy. 

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... 

Elemental abundances in CR2 chondrites normalized to the Cl composition and plotted in order of decreasing volatility from left to right. Lithophile elements are shown with open circles, siderophile elements with black circles, and chalcophile elements with gray circles. CR2 data from Kallemeyn etal. (1994). 

Volatile element abundances in CV chondrites (normalized to Cl chondrites and silicon) lie along a linear array on semi-log plots versus their 50% condensation temperatures. This depletion pattern persists, whether the elements are siderophile, lithophile, or chalcophile. 

Noble gas abundances in lunar soils and chondrites, (a) Elemental abundance patterns for trapped solar wind in lunar soils, normalized to solar system abundances, (b) Elemental abundance patterns for planetary trapped noble gases, normalized to solar system abundances. This diagram is intended to illustrate patterns only vertical positions are arbitrary. Modified from Ozima and Podosek (2002). 

Table 11.3 Average element abundances for anhydrous chondrite groups...

Elemental abundances, normalized to Mg and Cl chondrites, for two groups of primitive achondrites (acapulcoites and winonaites) that experienced low degrees of partial melting. These abundances are similar to chondritic abundances (average H-chondrite composition is illustrated). Modified from Mittlefehldt (2004). 

Figure 12.17a shows lithophile element abundances, and Figure 12.17b shows sid-erophile and chalcophile element abundances in CM chondrites, normalized to Cl chondrites. Illustrated for comparison are the abundances in CO chondrites, which are the anhydrous carbonaceous chondrite group most closely allied to CM chondrites. As in other chondrites, the greatest differences are in volatile elements. The volatile and moderately volatile elements in CM chondrites are present at 50-60% of the abundances of the refractory elements. The volatile elements are primarily located in the matrix, and the matrix comprises 50-60% of CM chondrites. This implies that the matrix has essentially Cl abundances of all elements, while the chondrules and refractory inclusions have Cl relative abundances of refractory elements but are highly depleted in the volatile elements. The sloping transition in the region of moderately volatile elements indicates... 

Chondrite-normalized abundances of siderophile elements in the Earth s mantle. The measured concentrations do not match those expected from low-pressure metal-silicate partition coefficients determined by experiments. Modified from Tolstikhin and Kramers (2008). 

Figure 7.1 Elemental abundance of noble gases relative to cosmic abundance (Anders Grevesse, 1989). Data for Earth (atmosphere), SW (solar wind implanted on A1 foils on the moon), Lunar (solar wind implanted on lunar soils), Q (chondrites), and Mars are from Table 3.2.

Table 10.1 Elemental abundances for several objects in the Solar System, normalized to Si and Cl chondrites. Following Halliday et al. 2001, Fodders 2003. Siderophile elements are indicated by. ...

The elemental abundance of the lunar mare rocks as compared to that of carbonaceous chondrites vary up to 6 orders of magnitude (Fig. 3a). The strongly siderophile elements and the very volatile elements are highly depleted, while the refractory elements Al, Ca, Ti, REE, Th, U. etc. are enriched. Hence, it is rather difficult to explain the fractionation of the lunar mare basalts by... 

With the above assumption, it is easy to calculate the absolute elemental abundances of the Moon from the observed K/La ratio in the lunar samples and the concentrations of K and La both in the HTC (as analyzed in the Allende inclusions) and in normal chondrites. 

Halbout J., Mayeda T. K., and Clayton R. N. (1986) Carbon isotopes and light element abundances in carbonaceous chondrites. Earth Planet. Sci. Lett. 80, 1-18. 

Figure 2 Magnesium- and Cl-normalized bulk lithophile (a, c) and siderophile (b, d) element abundances of the carbonaceous (a, b) and noncarbonaceous (c, d) chondrite groups (sources Kallemeyn and Wasson, 1981,1982,1985 Kallemeyn et al., 1978, 1989, 1991, 1994, 1996 Kallemeyn, unpublished).

Elemental abundance patterns for ordinary, Rumuruti-like (R), and Kakangari-like (K) chondrites are fairly flat and enriched relative to Cl for lithophile and refractory lithophile elements. Enstatite chondrites have the lowest abundance of refractory lithophile elements. 

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