The geological materials in Earth's lowermost mantle control the characteristics and interpretation of seismic ultra-low velocity zones at the base of the core-mantle boundary. Partial melting of the bulk lower mantle is often advocated as the cause, but this does not explain the nonubiquitous character of these regional seismic features. We explored the melting properties of mid-oceanic ridge ...

We present new laser ablation ICP-MS trace element concentration data for 28 elements in 97 mid-ocean ridge basalt (MORB) glasses that cover all major spreading centers as well as Tl concentration data for all mineral phases in five lherzolites from the Lherz massif, France. The ratio between the elements thallium (Tl) and cerium (Ce) is nearly constant in MORB, providing evidence that the depl...

6. Centers for Disease Control and Prevention. Update: interim recommendations for antimicrobial prophylaxis for children and breastfeeding mothers and treatment of children with anthrax. MMWR Morb Mortal Wkly Rep 2001;50:1014-6. 7. Henderson DW, Peacock S, Belton FC. Observations on the prophylaxis of experimental pulmonary anthrax in the monkey. J Hyg 1956;54:28-36. 8. Langmuir A, Popova I, S...

Experimental petrology and major element chemistry are used to infer the melting processes that operate in the upper oceanic mantle to yield basaltic magma, and the subsequent cooling processes by which these magmas chill to form the oceanic crust. THE PRIMARY MAGMAS OF MID-OCEAN RIDGE BASALTS This paper reports experiments carried out between 9 and 16 kbar (0.9 1.6 GPa) using natural, primitiv...

A substantial amount of subducted basaltic crusts may exist in the lower mantle. It features distinct chemical composition from peridotitic mantle and plays important roles dynamic evolution Earth's interior. However, mineral phases present crust is still poorly constrained. Here, we determined phase relations normal mid-ocean ridge basalt (MORB) up to 52 GPa at 2000 K by multi-anvil press. Thr...

We report stable Ni isotope compositions (?60/58Ni, relative to SRM986) for mafic lavas with a range of ?0.16‰ +0.20‰ (n = 44), similar that peridotite samples. Ocean island basalts (OIB) have been analysed from Iceland 6), the Azores 3), Galápagos Islands 2), and L??ihi, Hawaii 1). Samples (average ?60/58Ni +0.13 ± 0.16‰, 2s, n 7) display greatest in single OIB location this work, +0.01‰ +0.23...

Xe, produced from the radioactive decay of extinct I, and Xe, produced from extinct Pu and extant U, have provided important constraints on early mantle outgassing and volatile loss from Earth. The low ratios of radiogenic to non-radiogenic xenon (Xe/Xe) in ocean island basalts (OIBs) compared to mid-ocean ridge basalts (MORBs) have been used as evidence for the existence of a relatively undega...

1. Centers for Disease Control and Prevention. Poliomyelitis—Madagascar 2002. MMWR Morb Mortal Wkly Rep 2002;51:622. 2. Guillot S, Caro V, Cuervo N, Korotkova E, Combiescu M, Persu A, et al.] Natural genetic exchanges between vaccine and wild poliovirus strains in humans. J Virol 2000;74:8434–43. 3. Pringle CR. Virus taxonomy at the XIth International Congress of Virology, Sydney, Australia, 19...