Major and trace element content of the 17 lithostratigraphic units recovered during DSDP Leg 49 (Table 1)

• Main Authors: Tarney, J, Saunders, Andrew D, Bougault, Henri, Joron, Jean Louis, Treuil, M, Cann, Joe R
• Format: Dataset
• Language: English
• Published: PANGAEA 1979
• Subjects: 49-407; 49-408; 49-409; 49-410; 49-410A; 49-411; 49-412A; 49-413; Aluminium oxide; Caesium; Calcium oxide; Carbon dioxide; Cerium; Chromium; Cobalt; Deep Sea Drilling Project; DRILL; Drilling/drill rig; DSDP; DSDP/ODP/IODP sample designation; Elevation of event; Europium; Event label; Gadolinium; Glomar Challenger; Hafnium; Instrumental neutron activation analysis (INAA) (Reimann et al.; 1998); Iron oxide; Fe2O3; FeO; Lanthanum; Latitude of event; Leg49; Longitude of event; Lutetium; Magnesium number; Magnesium oxide; Manganese oxide; Neodymium; Nickel; Niobium; North Atlantic/BASIN; North Atlantic/FRACTURE ZONE; North Atlantic/RIDGE; Phosphorus oxide; Potassium oxide; Rubidium; Samarium; Mid-Atlantic Ridge; Reykjanes; Iceland; North Atlantic
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.710759; https://doi.org/10.1594/PANGAEA.710759

IPOD Leg 49 recovered basalts from 9 holes at 7 sites along 3 transects across the Mid-Atlantic Ridge: 63°N (Reykjanes), 45°N and 36°N (FAMOUS area). This has provided further information on the nature of mantle heterogeneity in the North Atlantic by enabling studies to be made of the variation of basalt composition with depth and with time near critical areas (Iceland and the Azores) where deep mantle plumes are thought to exist. Over 150 samples have been analysed for up to 40 major and trace elements and the results used to place constraints on the petrogenesis of the erupted basalts and hence on the geochemical nature of their source regions. It is apparent that few of the recovered basalts have the geochemical characteristics of typical "depleted" midocean ridge basalts (MORB). An unusually wide range of basalt compositions may be erupted at a single site: the range of rare earth patterns within the short section cored at Site 413, for instance, encompasses the total variation of REE patterns previously reported from the FAMOUS area. Nevertheless it is possible to account for most of the compositional variation at a single site by partial melting processes (including dynamic melting) and fractional crystallization. Partial melting mechanisms seem to be the dominant processes relating basalt compositions, particularly at 36°N and 45°N, suggesting that long-lived sub-axial magma chambers may not be a consistent feature of the slow-spreading Mid-Atlantic Ridge. Comparisons of basalts erupted at the same ridge segment for periods of the order of 35 m.y. (now lying along the same mantle flow line) do show some significant inter-site differences in Rb/Sr, Ce/Yb, 87Sr/86Sr, etc., which cannot be accounted for by fractionation mechanisms and which must reflect heterogeneities in the mantle source. However when hygromagmatophile (HYG) trace element levels and ratios are considered, it is the constancy or consistency of these HYG ratios which is the more remarkable, implying that the mantle source feeding a ...