Trace element distribution in mineral separates of the Allende inclusions and their genetic implications

Concentrations of the REE, Sc, Co, Fe, Zn, Ir, Na and Cr were determined by instrumental neutron activation and mass spectrometric isotope dilution analysis for mineral separates of the coarseand fine-grained types (group I and II of Martin and Mason's classification) of the Allende inclusions.These data, combined with data on mineral/liquid partition coefficients, oxygen isotope distributions and diffusion calculations, suggest the following: (1) Minerals in the coarse-grained inclusions (group I) crystallized in a closed system with respect to refractory elements. On the other hand, differences in oxygen isotope distributions among minerals preclude a totally molten stage in the history of the inclusion. Group I inclusions were formed by rapid condensation (either to liquid or solid) in a supercooled solar nebula; extrasolar pyroxene and spinel dust were included but not melted in the condensing inclusions, thus preserving their extrasolar oxygen isotope composition. REE were distributed by diffusion during the subsequent heating at subsolidus temperatures; because oxygen diffuses much more slowly at these temperatures, the oxygen isotope anomalies were preserved. (2) The fine-grained (group II) inclusions were also formed by condensation from a super-cooled nebular gas; however, REE-rich clinopyroxene and spinel were formed early and REE-poor sodalite and nepheline were formed later and mechanically mixed with clinopyroxene and spinel to form the inclusions. The REE patterns of the bulk inclusions and the mineral separates are fractionated, indicating that REE abundances in the gaseous phase were already fractionated at the time of condensation of the minerals. (3) Pre-existing Mg isotope anomalies in the coarse-grained inclusions must have been erased during the heating stage thus resetting the ²⁶Al-²⁶Mg chronometer.     

Trace elements in the Allende meteorite—I. Coarse-grained,Ca-rich inclusions

INAA of ten coarse-grained, melilite-spinel-bearing inclusions in the Allende meteorite for Ca, Sc, Hf, Ta, W, Os, Ir, Ru, La, Ce, Sm, Eu, Tb, Dy, Yb, Fe, Co, Cr and Au reveals that all of the refractory elements are enriched by a mean factor of 18.6 relative to their concentrations in Cl chondrites, consistent with a high-temperature condensation origin for the inclusions. Os, Ir and Ru were probably incorporated by the inclusions as tiny nuggets of an alloy in which they were dissolved in cosmic proportion to one another. Sc and Hf entered the inclusions in a separate phase, also in cosmic proportion, accompanied by a fraction of the REE. Bulk REE abundances are independent of the major minerals in the inclusions; yet, data from mineral separates suggest that the REE were partitioned between coexisting melilite and pyroxene according to crystal structure controls. A two-stage model is proposed in which the REE first entered the inclusions as trace, refractory condensate phases and then re-distributed themselves between the crystallizing major phases after the inclusions were melted in the nebula.     

Trace elements in the Allende meteorite—IV. Amoeboid olivine aggregates

INAA data for Ca, Sc, Hf, La, Ce, Sm, Eu, Tb, Yb, Lu, Os, Ir, Ru, Na, Cl, Br, Fe, Mn, Cr, Co, Au, As, and Sb are presented for ten amoeboid aggregates from the Allende meteorite. Only one lacks olivine. Seven of the remainder, as a group, have cosmic proportions of refractory lithophile and siderophile elements and appear to have formed when coarse-grained Allende inclusion material underwent partial reaction with a low-temperature nebular gas and mixture with FeO-rich olivine. The other two have highly fractionated abundances of refractory elements relative to one another compared to Cl chondrites, including Group II REE patterns, and probably formed by the mixing of fine-grained Allende inclusion material with FeO-rich olivine. Non-refractory siderophile components are also different in composition in each type of amoeboid olivine aggregate.     

Siderophile elements in chondrules of CV chondrites

New bulk compositional data for 34 Allende chondrules are presented. Whole chondrules were analyzed by instrumental neutron activation analysis (INAA). The new data set is evaluated together with older INAA data on Allende chondrules and recent INAA data on Mokoia chondrules. The Ni/Co ratios of 200 chondrules are close to the CI- or solar ratio. The chondritic Ni/Co ratios require an unfractionated chondritic metal source and set a limit to the fraction of metal lost from molten chondrules. The bulk chondrule Fe/Ni and Fe/Co ratios are more variable but on average chondritic. Iridium and other refractory metals have extremely variable concentrations in chondrules. High Ir chondrules have chondritic Ir/Sc ratios. They are dominated by CAI (Ca,Al-rich inclusion) components. Low Ir chondrules have approximately chondritic Ir/Ni ratios reflecting mixing with chondritic metal. In low Ir chondrules Ir correlates and in high Ir chondrules Ir does not correlate with Ni or Co. A large fraction of Ir may have entered chondrules in variable amounts as tiny grains of refractory metal alloys.Most Allende chondrules have Ir/Sc ratios below bulk meteorite ratios. Matrix must have a complementary high Ir/Sc ratio, as bulk Allende has approximately chondritic Ir/Sc ratio. Similarly, the high average Ir/Ni ratios of Allende chondrules must be balanced by low Ir/Ni ratios in matrix to obtain the bulk Allende Ir/Ni ratio, which is close to the average solar system ratio.More recent data on single chondrules from Allende by ICP-MS (Inductively Coupled Plasma Mass Spectrometry) and ICP-OES (Inductively Coupled Optical Emission Spectrometry) show the same trends as the INAA data discussed here.     

Additional estimates of continental surface Precambrian shield composition in Canada

New trace element analyses have been made on the composite Canadian Precambrian shield samples reported in 1967.The overall mean abundance of Cr has been revised to 35 ppm (from 99). New abundances similar to 1967 values are (in ppm): Ni, 19; Co, 12; Cu, 14; Zr, 300; Sr, 315; Ba, 1070; Rb, 110: individual 1967 Rb values were erroneous.Elements not previously determined have the following overall mean values (in ppm): Zn, 52; Sc, 7.0; Nb, 26; Hf, 6.9; La, 32; Ce, 65; Nd, 26; Sm, 4.5; Eu, 0.94; Gd, 2.8; Tb, 0.48; Ho, 0.62; Yb, 1.5; Lu, 0.23; Y, 21; Pb, 17; values in ppb are: Ir, 0.02; Au, 1.8; Tl, 520.Clear positive correlations among Mg-Cr-Ni-Ir-Au appear for all rock-types, marble and quartzite as well as mafic igneous. Regional differences are apparent for several elements: e.g. higher Au, Ir, Cr, Ni in Baffin Island and Northern Quebec composites, compared with Saskatchewan and Southwestern Quebec; high Ti, Zn, Nb, Zr, Hf, REE, Y, Sr, K/T1 abundances and negative Eu anomalies in Southwestern Quebec.The overall REE abundances (omitting Southwestern Quebec) differ from other surface continental crustal rock estimates.     

Trace elements in the Allende meteorite—II. Fine-grained. Ca-rich inclusions

Nine fine-grained feldspathoid-, grossular-, spinel-, pyroxene-bearing inclusions from the Allende meteorite were analysed by instrumental neutron activation analysis. On the average, these inclusions are enriched in the refractory lithophile elements Ca, Sc, Ta and the rare earths by factors of 5–30 relative to Cl chondrites but are depleted in the refractory and volatile siderophiles, Ir, Co and Au. The volatile elements Fe, Cr and Zn are present at levels of 3.38–8.51%, 326–2516 ppm and 308–1376 ppm, respectively. Textural, mineralogical and chemical data suggest that the fine-grained inclusions formed in the solar nebula by the simultaneous condensation of volatiles and refractory lithophile elements which failed to condense into the coarse-grained, high-temperature condensate inclusions. The marked differences in the enrichment factors for different refractories in the fine-grained inclusions are caused by relatively small differences in their accretion efficiencies into the coarse-grained ones. The trace element data indicate that the refractories in the fine- and coarse-grained inclusions can only be the cosmic complements of one another if the fine-grained ones represent no more than ~ 20% of the most abundant refractory elements.     

The Compositions of Six Chinese Ordinary Chondrites and Element Distributions in Their Different Phases

Six Chinese ordinary chondrites (four of them have fallen in recent years and the trace element abundances have not yet been reported for the other two) were examined.The contents of 21 elements (Na,Cr,Mn,Sc,Se,Zn,Br,Ni,Fe,Co,Ir,Cu,Ga,As,Au,Sb,Os,W,Re,Pt,and Ru)in the magnetic fractions and 20 elements (Na,K,Ca,Sc,Cr,Mn,Fe,Co,Ni,Zn,Se,Br,La,Sm,Eu,Yb,Lu,Ir,Au,and As) in the non-magnetic fractions were de-termined by INAA. The results indicate that the 5 H-group chondrites show almost no difference in composition,but they are different from the Zhaodong L-group chondrite in elemental abundance.As a normalized element(relative to CI),the concentrations of Ga in the magnetic fractions can be used to classify ordinary chondrites(H-,L- and LL-group).The bulk composition and modal weight of each component calculated from element concentrations in different phases are in good agreement with the bulk rock analyses presented in the literature.     

Origin of compact type A refractory inclusions from CV3 carbonaceous chondrites

Compact type A (CTA) inclusions are one of the major types of coarse-grained refractory inclusions found in carbonaceous chondrites. They have not been studied in a systematic fashion, leading to some uncertainties and unproven assumptions about their origin. To address this situation, we studied a total of eight CTAs from Allende, Efremovka and Axtell by scanning electron-microscopic and electron and ion-microprobe techniques. These inclusions are very melilite-rich, ranging from ∼60 vol% to nearly monomineralic. Also present are Mg–Al spinel (5–20%), perovskite (trace–∼3%) and, in some samples, Ti-rich (∼17 wt% TiO₂^tot) fassaite (trace–∼20%), and rhönite (≤1%). Melilite compositions are mostly between Åk₁₅ and Åk₄₀. Chondrite-normalized REE abundance patterns for melilite (flat at ∼10 × CI with positive Eu anomalies) and fassaite (slight HREE enrichment relative to LREE and negative Eu anomalies) are like those for their counterparts in once-molten type B inclusions. The patterns for rhönite have positive slopes from La through Lu and abundances <10 × CI for La and 35–60 × CI for Lu. Features of CTAs that suggest that they were once molten include: rounded inclusion shapes; positively correlated Sc and V abundances in fassaite; radially oriented melilite laths at inclusion rims; and the distribution of trace elements among the phases. Fractional crystallization models show that, with one exception, the REE contents of perovskite and fassaite arose by crystallization of these phases from late, residual liquids that would have resulted from prior crystallization of the observed proportions of melilite and spinel from liquids having the bulk compositions of the inclusions. One Allende CTA (TS32), however, has several features (irregular shape, reversely zoned melilite, fassaite REE contents) that are not readily explained by crystallization from a melt. This inclusion may have undergone little melting and may be dominated by relict grains.     

Allende inclusions: volatile-element distribution and evidence for incomplete volatilization of presolar solids

Neutron activation data on 14 trace elements in Allende bulk samples and in fractions of spheroidal Ca-Al-rich inclusions show several distinct distribution patterns. Refractories Ir and Sc have high inclusion/bulk ratios and show little variation with depth. Manganese, Fe, Co, Ni, Ga, Cd and In have low inclusion/bulk ratios and decrease with increasing depth; their presence in the inclusions reflects matrix contamination. Sodium and other alkalies have high inclusion/bulk ratios (near 0.5) and decrease with increasing depth; their high concentration despite moderate volatility seems related to condensation reactions in which refractory Al-bearing minerals are reactants. Chromium, Zn, Ge and Au show patterns similar to those of the alkalies; this seems to indicate that refractory minerals are reactants in their condensation reactions, but thermodynamic support for this hypothesis has not been found.We propose that the large size of Allende spheroidal inclusions indicates an origin by incomplete vaporization of presolar solid matter followed by recondensation of refractories on a limited number of condensation nuclei. The low abundance of large refractory inclusions in ordinary and enstatite chondrites reflects complete vaporization of presolar solids at their formation locations; constraints on homogeneous nucleation resulted in the simultaneous condensation of refractories and olivine at these locations.Quadruplicate analyses of the Orgueil chondrite are in good agreement with previous determinations with the exception of small systematic differences in Au and Ir.     

Chemical compositions of refractory inclusions in the Murchison C2 chondrite

Samples from ten refractory inclusions in Murchison, some of which are splits of inclusions whose mineralogical and petrographic characteristics are known, have been analysed for thirty-six elements by neutron activation. Six inclusions have group II or group III patterns or variants of such patterns. Two inclusions, BB-5 and MUCH-1, have large negative Yb anomalies unaccompanied by correspondingly large negative Eu anomalies. It is possible that the latter condensed originally with group III patterns and preferentially took up Eu in later exchange processes under reducing conditions. One inclusion, SH-2, has heavy REE enrichment factors that increase with the refractoriness of the REE, indicating the presence of an extremely high-temperature, or ultrarefractory, REE condensate, but it also has a heavy REE/light REE ratio that indicates mixing of that component with a lower-temperature REE condensate. The frequency of highly fractionated REE patterns and absence of group I patterns suggest that refractory inclusions in Murchison stopped equilibrating with the nebular gas at higher temperatures than most Allende coarse-grained inclusions. The lower Ir/Os and Ru/Re ratios of some Murchison inclusions compared to those of Allende coarse-grained inclusions indicate that condensate alloys that contributed noble metals to the former also stopped equilibrating with the nebular gas at higher temperatures than those that contributed noble metals to the latter. Murchison inclusions tend to be lower in non-refractory elements than Allende coarse-grained inclusions, suggesting that, on average, the former underwent less severe secondary alteration than the latter.     

Elemental composition of individual chondrules from carbonaceous chondrites,including Allende

Major and trace element analyses of over 180 individual chondrules from 12 carbonaceous chondrites are reported, including individual analyses of 60 chondrules from Pueblito de Allende. Siderophile elements in most chondrules are depleted, compared to the whole chondrite. Correlations of Al-Ir and Ir-Sc among chondrules high in Ca and Al were observed. A Cu-Mn correlation was also found for chondrules from some meteorites. No correlation was observed between Au and other siderophile elements (Fe, Ni, Co and Ir). It is suggested that these elemental associations were present in the material from which the chondrules formed. Compositionally, chondrules appear to be a multicomponent mixture of remelted dust. One component displaying an Al-Ir correlation is identified as Allende-type white aggregates. The other components are a material chemically similar to the present matrix and sulfides-plus-metal material. Abundances of the REE (rare earth elements) were measured in ‘ordinary’ Allende chondrules and were 50% higher than REE abundances in Mokoia chondrules; REE abundances in Ca-Al rich chondrules were similar to REE abundances in Ca-rich white aggregates.     

中国金伯利岩地球化学

本文利用了100多个金伯利岩的主要元素及微量元素分析结果,用Si/Mg、C.l——(SiO_2+Al_2O_3+Na_2O)/(MgO+2K_2O)、Mg/(Mg+Fe)比值及SiO_2、Al_2O_3及Na_2O含量研究了金伯利岩的混染程度。结果表明,绝大部分金伯利岩受到了混染作用的影响,它们的成分实际上不能代表形成这些岩石的岩浆的成分。金伯利岩的Al_2O_3和Na_2O的含量比其他碱性超基性及基性岩石的Al_2O_3和Na_2O含量低得多。含金刚石的金伯利岩比不含金刚石的金伯利岩的MgO、(Cr_2O_3+NiO)高,而TiO_2+Al_2O_3+Na_2O+K_2O+P_2O_5低。 我国金伯利岩中Cr-Al,Ni-Co,Ni-Cr,Ni-V,Sc-Ti,Zn-Ti,Ba-Sr,Zr-Hf,Nb-Ta,U-Th,K-Rb呈正相关关系。     

Refractory trace elements in Ca-Al-rich inclusions in the Allende meteorite

The condensation temperatures are calculated for a number of refractory trace metals from a gas of solar composition at 10^?3 and 10^?4 atm. total pressure. Instrumental neutron activation analysis of Ca-Al-rich inclusions in the Allende carbonaceous chondrite reveals enrichments of 22.8 ± 2.2 in the concentrations of Ir, Sc and the rare earths relative to Cl chondrites. Such enrichments cannot be due to magmatic differentiation processes because of the marked differences in chemical behavior between Ir and Sc, exhibited by their distributions in terrestrial igneous rocks and meteorites. All of these elements should have condensed from a cooling gas of solar composition above or within the range of condensation temperatures of the major mineral phases of the inclusions, which suggests that these inclusions are high-temperature condensates from the primitive solar nebula. Gas-dust fractionation of these materials may have been responsible for the depletion of refractory elements in the ordinary and enstatite chondrites relative to the carbonaceous chondrites.     

Chemical evolution of metal in refractory inclusions in CV3 chondrites

Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) was used to measure distributions of the siderophile elements V, Fe, Co, Ni, Mo, Ru, Rh, Pd, W, Re, Os, Ir, Pt, and Au in Fremdlinge with a spatial resolution of 15 to 25 μm. A sulfide vein in a refractory inclusion in Allende (CV3-oxidized) is enriched in Rh, Ru, and Os with no detectable Pd, Re, Ir, or Pt, indicating that Rh, Ru, and Os were redistributed by sulfidation of the inclusion, causing fractionation of Re/Os and other siderophile element ratios in Allende CAIs. Fremdlinge in compact Type-A inclusions from Efremovka (CV3-reduced) exhibit subsolidus exsolution into kamacite and taenite and minimal secondary formation of V-magnetite and schreibersite. Siderophile element partitioning between taenite and kamacite is similar to that observed previously in iron meteorites, while preferential incorporation of the light PGEs (Ru, Rh, Pd) relative to Re, Os, Ir, and Pt by schreibersite was observed. Fremdling EM2 (CAI Ef2) has an outer rim of P-free metal that preserves the PGE signature of schreibersite, indicating that EM2 originally had a phosphide rim and lost P to the surrounding inclusion during secondary processing. Most Fremdlinge have chondrite-normalized refractory PGE patterns that are unfractionated, with PGE abundances derived from a small range of condensation temperatures, ∼1480 to 1468 K at P_tot = 10⁻³ bar. Some Fremdlinge from the same CAI exhibit sloping PGE abundance patterns and Re/Os ratios up to 2 × CI that likely represent mixing of grains that condensed at various temperatures.     

The mineralogy,geochemistry and origin of Iherzolite inclusions in Victorian basanites

The mineralogy of Iherzolite inclusions in Victorian basanites indicates an upper mantle origin, but a range of temperatures from igneous to metamorphic (subsolidus) is indicated by the mineral compositions. Pyroxene textural features exhibit a slow cooling history consistent with isotopic evidence that these inclusions are accidental xenoliths. Clinopyroxene-rich inclusions (10–20 vol. % cpx) have higher abundances of Ca, Na, AI, Sc, V, Cr and heavy REE, lower Mg/Mg + Fe²⁺, lower Ni abundances, and more fayalitic olivines than clinopyroxene-poor inclusions (<5 vol. % cpx). A surprising result is that the refractory Mg-rich, clinopyroxenepoor inclusions contain the highest abundances of incompatible elements such as P, K, Ti, light REE, Th and U. We believe these inclusions are composed of two components (A and B). Component A determines the major element abundances and primary mineralogy of the inclusions. Based on Ni abundances component A is interpreted as a melting residue rather than a crystallization accumulate. Component B forms a small and varying portion of the inclusions, and it contributes P, K, Ti, light REE, Th and U. This component has the geochemical characteristics of a liquid formed in equilibrium with garnet.The following model is presented for the origin of Iherzolite inclusions. Residual Iherzolite (Component A) is left in the lithosphere after partial fusion, and it is later modified by a melt which has migrated to the top of the low velocity zone. Because this liquid (Component B) results from a small degree ( <6 per cent) of melting (probably limited by water abundance), and has equilibrated with garnet, it will be very enriched in P, K, Ti, light REE, Th and U. Subsequent cooling and recrystallization forms the present mineralogy. Finally, explosive volcanism, characteristic of silica-undersaturated magmas, incorporates mantle fragments (Iherzolite inclusions), and the increasing temperature and decreasing pressure during ascent causes incongruent melting of minor hydrous phases such as phlogopite and amphibole.     

Geochemical characteristics of central Chile (33 °–34 °S) granitoids

Seventeen granitoid samples from batholiths in central Chile (33 °–34 ° S) have been analyzed for trace element content. The samples range in age from Paleozoic to Tertiary, and in rock type from quartz diorite to granite. In general, compared to andesites from central-south Chile these rocks are more siliceous with lower abundances of compatible trace elements and higher abundances of incompatible trace elements. However, Upper Tertiary granodiorites have important geochemical similarities, such as highly fractionated rare-earth element (REE) distributions relative to chondrites, to some modern andesites in this region; e.g., Marmolejo. Similar highly fractionated REE distributions are also common in the cores of zoned intrusive sequences in the Sierra Nevada of the western U.S. Based on limited sampling of central Chile Cretaceous and Tertiary plutonics, there may be a west to east increase in light REE/heavy REE ratio and in Sr content. Compared to the Upper Tertiary granodiorites, the Paleozoic granodiorites have similar REE abundances but lower Sr, Sc, Cr, Co, and Ni contents.     

Chemical and Sr isotopic characterization of North America uranium ores: Nuclear forensic applications

This study reports major, minor, and trace element data and Sr isotope ratios for 11 uranium ore (uraninite, UO_2+x) samples and one processed uranium ore concentrate (UOC) from various U.S. deposits. The uraninite investigated represent ores formed via different modes of mineralization (e.g., high- and low-temperature) and within various geological contexts, which include magmatic pegmatites, metamorphic rocks, sandstone-hosted, and roll front deposits. In situ trace element data obtained by laser ablation-ICP-MS and bulk sample Sr isotopic ratios for uraninite samples investigated here indicate distinct signatures that are highly dependent on the mode of mineralization and host rock geology. Relative to their high-temperature counterparts, low-temperature uranium ores record high U/Th ratios (>1000), low total rare earth element (REE) abundances (<1 wt%), high contents (>300 ppm) of first row transition metals (Sc, Ti, V, Cr, Mn, Co, Ni), and radiogenic ⁸⁷Sr/⁸⁶Sr ratios (>0.7200). Comparison of chondrite normalized REE patterns between uraninite and corresponding processed UOC from the same locality indicates identical patterns at different absolute concentrations. This result ultimately confirms the importance of establishing geochemical signatures of raw, uranium ore materials for attribution purposes in the forensic analysis of intercepted nuclear materials.     

Chemical evidence for the genesis of the ureilites, the achondrite Chassigny and the nakhlites

Major element and REE, Cr, Sc, V, Ni, Co, Ir, Au, Sr, Ba abundances were determined in three ureilites and the unique achondrite, Chassigny. Chondritic-normalized REE abundance patterns for the ureilites are v-shaped, similar to pallasites, indicating a possible deep-seated origin. The lithophile trace element abundances and v-shaped REE patterns of the ureilites are consistent with a two-stage formation process, the first of which is an extensive partial melting of chondrite-like matter to yield ureilite precursors in the residual solid, which is enriched in Lu relative to La. The second step consists of an admixture of small and variable amounts of material enriched in the light REE. Such contaminating material may be magmas derived from the first formed melt of partial melting of chondrite-like matter.

In contrast to the ureilites, Chassigny has a chondritic-normalized REE pattern which decreases smoothly from La(1.8 × ) to Lu(0.4 × ) and is parallel to and ˜0.25 × the REE pattern in the nakhlitic achondrites. The composition of the magma from which Chassigny crystallized was highly enriched in the light REE; e.g. chondritic normalized La/Lu ˜ 7. The similarity in the fractionated REE patterns (no Eu anomalies) for the olivine-pyroxene Chassigny and for the nakhlites suggests a genetic relationship.

Siderophile trace element relationships in ureilites can be interpreted by three components: (1) ultramafic silicates enriched in Co relative to Ni, (2) an indigenous metal phase remaining after the partial melting event, and (3) a component of the carbon-rich vein material added after the partial melting.     

Mineralogical and chemical changes of soil and stream sediment formed by intense weathering of the Danburg granite, Georgia, U.S.A.

A series of soil and stream sediments developed during intense weathering on the metaluminous Danburg granite, northeastern Georgia, U.S.A., have been analyzed mineralogically and chemically. The concentrations of Ba, Na, Rb and Cs in the silt and coarser fractions are controlled mainly by feldspars and biotite. Hf is controlled by zircon, and the REE (rare-earth elements) and Th are largely controlled by sphene. Variations in feldspar, sphene and zircon may produce small variations in Eu/Sm and La/Lu ratios. Ferromagnesian minerals control Ta, Fe, Co, Sc and Cr concentrations.

The mineralogical and chemical composition of the Danburg granite is more closely reflected in the silt than in the sand or gravel fractions of stream sediments. In the silt, the contents of Rb, REE, Th, Ta, Fe, Co and Sc and the ratios of La/Sc, Th/Sc, La/Co, Th/Co, Eu/Sm and La/Lu are similar to those in the unweathered granite. In contrast, these element contents or ratios in the sands and gravels are 0.05−3× the concentration in the unweathered granite. Ta and Ba contents are an exception to the above. The Ta and Ba contents of the sands and gravels are similar to those of the granite.

In the kaolinite-halloysite clays, the content of Na is depleted relative to the source. Rb, Cs, Ba, Hf and Ta are depleted or enriched in the clays relative to the source, while the REE, Th, Fe, Co, Sc and Cr are enriched. The Eu/Sm (Eu anomaly size) and La/Lu ratios, and the REE patterns of the clays are similar to those of the source.

Thus, the mineralogy and element contents of a siltstone developed from metaluminous, granitic sources during intense weathering would be expected to be more similar to the source rock than the sandstones and conglomerates. Claystones should contain similar REE patterns and Eu/Sm ratios as the source rock, but such fine-grained sediments might represent much larger areas of source rocks than the more locally derived sandstones or conglomerates.