Eighty per cent of all mid-ocean spreading centres are slow. Using a mixture of global bathymetry data and ship-board multibeam echosounder data, we explore the morphology of global mid-ocean ridges and compare two slow spreading analogues: the Carlsberg Ridge in the north-west Indian Ocean between 571E and 601E, and the Kane to Atlantis super-segment of the Mid-Atlantic Ridge between 211N and ...

Abstract The Central Asian Orogenic Belt (CAOB) is one of the largest accretionary orogens on Earth and preserves evidence that more than 50% this orogen represents juvenile crustal growth over an extended period some 750 million years from ca. 1000 Ma to 250 Ma. However, mechanism controversial, as implied by a variety proposed models ranging contributions mantle-derived basaltic underplating ...

We derive an estimate for the chemical composition of the depleted MORB mantle (DMM), the source reservoir to mid-ocean ridge basalts (MORBs), which represents at least 30% the mass of the whole silicate Earth. A database for the chemical and physical properties of abyssal peridotites has become robust and complete enough to truly access a reference DMM. Using trace element depletion trends fro...

The flow of lava into the ocean at the shoreline of Kilauea Volcano during the ongoing Pu’u O’o eruption has allowed a detailed study of the geochemical interaction between lava and seawater. This paper focuses on the chemistry of the major and minor elements in the fluids that resulted from this interaction. The elemental enrichments in these fluids are dominated by three processes: (1) evapor...

Abstract The Rio Grande Rise in the western South Atlantic Ocean has been interpreted as either an oceanic plateau related to Tristan-Gough mantle plume, or a fragment of detached continental crust. Here we present new major and trace element data for volcanic rocks from eastern adjacent Jean Charcot Seamount Chain. older parts are comprised tholeiitic basalt with moderately enriched compositio...

Ascertaining the emplacement mechanism of oceanic basaltic lavas is important in understanding how ocean floor topography produced and plates evolve, particularly during early stages crustal development a supra-subduction zone. A detailed study volcanic stratigraphy at International Ocean Discovery Program (IODP) Site U1438 Amami Sankaku Basin, west Kyushu–Palau Ridge, has revealed lava accreti...

Earth’s dominant form of magmatism occurs at mid-ocean ridges (MORs), producing the igneous crust for two-thirds of the planet’s surface and conveying significant heat and material fluxes from the mantle to the world’s oceans. Mid-ocean-ridge basalt (MORB) magmas form from upwelling compositionally heterogeneous mantle1 by aggregation of near-fractional melts beneath spreading centres2. Multipl...

[1] Geochemical heterogeneity within the mantle has long been recognized through the diversity of trace element and radiogenic isotopic compositions of mantle-derived rocks, yet the specific origin, abundance, and distribution of enriched material within the mantle have been difficult to quantify. In particular, the origin of the distinctive geochemical characteristics of Indian mantle has been...

The Pb isotope ratios of 13 sediment samples, collected during Ocean Drilling Program Leg 145 at Sites 881, 883, and 884 in the North Pacific east of the Kamchatkan trench, were determined. The sediments were selected from continuously recovered cores and are representative of the range of sediment compositions recorded. The sediments analyzed are predominantly pelagic oozes, representing appro...