• journal_title：Geology
• Contributor：David D. Lambert ; Steven B. Shirey ; Steven C. Bergman
• Publisher：Geological Society of America
• Date：1995-
• Format：text/html
• Language：en
• Identifier：10.1130/0091-7613(1995)023<0273:PLMSFT>2.3.CO;2
• journal_abbrev：Geology
• issn：0091-7613
• volume：23
• issue：3
• firstpage：273

Geochemical and isotopic studies of the Cretaceous (106 Ma) Prairie Creek olivine lamproites in southwestern Arkansas indicate that these diamond-bearing ultrapotassic magmas were derived from metasomatized Proterozoic subcontinental lithospheric mantle. Re-Os isotopic data yield a nonradiogenic initial γ_Os = –3.2 to –3.6 (percent deviation in ¹⁸⁷Os/¹⁸⁸Os from chondritic mantle) and mantle model ages (T_MA) of 0.9 to 1.2 Ga. Sm-Nd isotopic data yield a nonradiogenic initial ϵ_Nd = –10 and a depleted mantle model age (T(DM)) of 1.2 Ga. These data are consistent with initial stabilization of low-density lithospheric mantle at ∼1.2 Ga, followed closely in time by reenrichment in incompatible trace elements. This Middle Proterozoic lithospheric mantle source is younger than overlying Early Proterozoic crust of the southern U.S. midcontinent. Pre-Grenville subduction of oceanic lithosphere may have juxtaposed 1.2 Ga mantle beneath 1.6 to 2.0 Ga crust and imparted the necessary slab-derived chemical components for the growth of diamonds.