Slave Craton peridotites

Cr-poor variety widespread, locally abundant (e.g.. Monastery). Garnets, clino- and orthopyroxenes, phlogopite and ihnenite most common, zircon and olivine rarer. Debatable whether phlogopite and olivine are members of Cr-poor suite. Wide range in chemistry but Cr-poor, Fe-Ti-rich relative to type I (low-Z) peridotite minerals. Mineral chemistry and estimated equilibration P/Ts overlap those of type V (high-Z) Iherzolites. Some Slave craton Cr-poor megacrysts show mineral chemistry links to type II megacrystalline pyroxenite xenoliths. See review of Schulze (1987). 

Cratonic peridotite xenoliths from Lesotho, S. Africa, the Jericho kimberlite, Slave craton, and Somerset Island, Churchill Province, northern Canada, along with selected samples from... 

Slave craton (Irvine et al, 1999,2003) which have all produced Archean Re-Os model ages. Some model ages range to in excess of 3.5 Ga but most are in the region between 2.7 Ga and 3.2 Ga (Figure 44). Archean ages are obtained from peridotites derived from well into the diamond stability field. 

Irvine G. J., Carlson R. W., Kopylova M. G., Pearson D. G., Shirey S. B., and Kjarsgaard B. A. (1999) Age of the lithospheric mantle beneath and around the Slave craton a rhenium-osmium isotopic study of peridotite xenoliths from the Jericho and Somerset Island kimberlites. In Abst. Ninth Annual V. M. Goldschmidt Conference LPI contribution no. 971. Lunar and Planetary Institute, Houston, pp. 134-135. 

Kopylova M. G., Russell J. K., and Cookenboo H. (1999) Petrology of peridotite and pyroxenite xenoliths from the Jericho kimberlite implications for the thermal state of the mantle beneath the Slave craton, northern Canada. J. Petrol. 40, 79-104. 

Table 1. PGE and Os isotope data for selected whole-rock peridotites from the Slave Craton, Namibia and Vitim... 

To illustrate the appUcation of these methods we have analysed selected samples from different suites of cratonic peridotites for PGE abundances and Re-Os isotopic composition that had been previously analysed for major elements (Table 1). The sample set comprises three peridotites from the Jericho kimberlite, Northern Slave Craton (Irvine et al. 1999 Kopylova Russell 2000) two peridotites from the Kaapvaal Craton (Pearson et al. 1995a Carlson et al. 1999) three peridotites from the Farm Louwrencia kimberlite, Southern Namibia, on the periphery of the Kaapvaal Craton (Pearson et al. 1994, 1998a Hoal et al. 1995 Frantz et al. 1996) three peridotites from the Vitim alkali basalt field, on the southern margin of the Siberian Craton (Ionov et al. 1993 Pearson et al. 19986). 

Fig. 5. Histogram of Trd ages for peridotites from the Jericho kimberlite, Nothern Slave Craton. Data from Irvine et al. (2001).

Fig. 6. Chondrite-normalized PGE patterns of whole-rock peridotites from the Jericho kimberlite. Northern Slave Craton and for Kaapvaal peridotites. Data from Table 1. Normalizing values taken from McDonald et al. (1995).

Figure 43 CHf versus cnj isotope diagrams for lithospheric mantle peridotite minerals. Kaapvaal peridotite data are ah garnets and clinopyroxenes (Simon et al, 2002). Slave peridotite data are garnets and whole rocks from Schmidberger et al (2002). Salt Lake Crater peridotites (Hawaii), Kilboume Hole and Abyssal peridotites, are from Salters and Zindler (1995). Siberian and Mongohan peridotite Held are chnopyroxene data from cratonic and off-craton peridotites (field taken from Ionov and Weis, 2002). Fields for MORE (N-MORB) and OIB are from Nowell et al (1998). Field for Beni Bousera peridotites from Pearson and Noweh (2003).

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