The Rooiberg Group is a 6-km-thick sequence of mostly volcanic rocks, which represent the first phase of magmatic activity associated with the Bushveld Complex. These strata include, in ascending stratigraphic order, the Dullstroom, Damwal, Kwaggasnek, and Schrikkloof Formations. Units of the lower Dullstroom Formation range from basalts to andesites and comprise two compositional suites: high ...

Using infrared spectroscopy, we found that changes in the in-plane charge dynamics attributable to static stripe order in La(1.275)Nd(0.6)Sr(0.125)CuO(4) or superconductivity in La(1.875)Sr(0.125)CuO(4) are confined to energies smaller than 100 cm(-1). An absorption peak in the low- omega conductivity of the Nd-doped compound is suggestive of localization effects due to the reduced dimensionali...

Post-collisional alkaline intrusive rocks from the Dabie orogen were studied for their whole-rock major-trace elements and Sr-Nd-Hf-Pb isotopes, as well zircon U-Pb ages Hf-O isotopes. The results provide geochemical constraints on nature of mantle sources thus insight into crust-mantle interaction in continental collision zone. are composed syenite nepheline syenite. Syn-magmatic dating by LA-...

New measurements of Os, He, Sr and Nd isotopes, along with major and trace elements, are presented for basalts from the three volcanic flank zones in Iceland and from Jan Mayen Island. The Os/Os ratios in lavas with <30 ppt Os (n = 4) are elevated compared to ratios in coexisting olivine and appear to be contaminated at a shallow level. The Os/Os ratios in the remaining lavas with >30 ppt Os (n...

An ion probe study of trace elements in Mg-rich clinopyroxene phenocrysts in primitive Aleutian lavas provides constraints on the genesis of Aleutian adakites, and possible insights into the source of common Aleutian magmas. Clinopyroxene (cpx) phenocrysts in the primitive adakites have high Sr and Nd=Yb compared to cpx in Aleutian basalts. In the adakites, Sr and Nd=Yb are highest for high Mg#...

Lavas from Afanasy-Nikitin Rise, possibly the Late Cretaceous product of the Crozet hotspot, cover a wide range of isotopic compositions that includes the lowest (Pb/Pb)t (to 16.77) and «Nd(t) (to 28) values yet found among oceanic islands or spreading centers worldwide, as well as high (Sr/Sr)t (to 0.7066). In contrast, young basalts from the Crozet Archipelago exhibit a narrow range of variat...

Plio–Pleistocene (3.4–0.125 Ma) post-plateau magmatism in the Meseta del Lago Buenos Aires (MLBA; 46.7jS) in southern Patagonia is linked with the formation of asthenospheric slab windows due to ridge collision along the Andean margin f 6 Ma ago. MLBA post-plateau lavas are highly alkaline (43–49% SiO2; 5–8% Na2O+K2O), relatively primitive (6–10% MgO) mafic volcanics that have strong OIB-like g...

Continental flood basalts and mid-ocean ridge (MOR) tholeiitic basalts have distinctly different 14 3 Ndf1 44 Nd which may permit a priori distinctwn between '"continental" and "oceanic" igneous rocks. Initial 14 3 NdJI 4 4 Nd of continental igneous rocks through time fall on a Sm/Nd evolution curve with chondritic REE abundance ratio. These observations indicate that many continental igneous r...