1,721,103 research outputs found
Preliminary results on the structure of ocean crust from new Holes drilled in fast-spread crust during ODP Leg 206
No full text3D-Structure of upper oceanic crust formed at a superfast spreading ridge (ODP-IODP Site 1256, equatorial Pacific): A core-log integration approach
No full textCaratterizzazione strutturale e petrofisica della sezione vulcanica sommitale di una crosta oceanica intatta
No full textStructural and petrophysical characterization of the upper basement crustal section at ODP/IODP Site 1256 (East Pacific Ocean)
No full textNew ocean crust is constantly being formed from mid-ocean ridge axis. Voluminous flows of lava are emplaced also away from the ridge axis, adding off-axis crustal layers to the crustal pile. Research on deep sea is of great importance to better understand the mechanisms and the nature of the crust forming and evolution. In this work, we decipher the first stages of the postmagmatic evolution of an intact volcanic section from the upper oceanic crust at ocean drilling program/integrated ocean drilling program (ODP/IODP) Site 1256 (Eastern Pacific Ocean). Using for the first time an innovative core-log integration technique to match direct (core-related) and indirect (borehole-related) data by depth shifting and reorienting individual core pieces recovered by drilling, we are able to identify the clusterization of structures and physical properties within distinct downdeep "strong" and "weak" lava zones, reflecting the cooling and tectonic evolution of lavas rather than lithological variations. We define the evolution of the structural zones that typically affect lava flows: colonnades and entablature zones, studying an off-axis lava flow encountered in present-day upper ocean crust. For the same off-axis flow, we are also able to suggest the lava flow direction (NW-SE) and its relationships with the paleoridge axis. Despite the environmental difficulties in the study of the subseafloor under deep water and using only one-dimensional data deriving from ocean drilling, this work shows how an array of diverse data can be integrated into a coherent interpretation of lava flow history obtaining detailed information on the mechanism of submarine lava emplacement and flow. Key Points We deciphered the solidification rate scheme of a subseafloor lava body We found the flowing direction of the off-axis lava flow at ODP Site 1256 We define the structural control on the physical properties at ODP Site 125
Mantle peridotites and cumulates from the Elba Island ophiolites: fragments of the oceanic mantle-crust transition zone
No full textThe ophiolites of the Elba Island have been correlated with the other Mesozoic ophiolites of the Northern Apennines, in particular they have been related to the Internal Ligurides which represent sub-oceanic mantle-derived peridotites. In eastern Elba, ophiolites consist of several tectonic slices composed by serpentinized peridotites, gabbros, mafic-ultramafic cumulates, and volcanic basalts which are overlain by thick sedimentary formations of Mid-Late Jurassic to Cretaceous age. This paper contains a short description of the petrographic and microchemical features of the ultramafic/mafic ophiolitic sections cropping out in the Sassi Turchini, Rio nell'Elba and Rio Marina areas. The results are discussed on the basis of the most recent hypotheses regarding the evolution of the present-day oceans
Rock type assemblage and metamorphic evolution of the Antrona ophiolite (NE Piemonte, western Alps)
No full textPreliminary Results on the Structure of Ocean Crust from new Holes Drilled in Fast-Spread Crust During ODP Leg 206
No full textBrecce serpentinitiche nel massiccio ultrabasico del Monte Avic (Falda Ofiolitica Piemontese): possibili evidenze di erosione sottomarina
No full textPolyphase HP metamorphism in the ophiolitic glaucophanites of the lower St. Marcel valley (Aosta valley)
No full textextural and chemical evidences give some insights on the HP tectono-metamorphic events that affected the ophiolitic glaucophanites of the St. Marcel Valley (Aosta, Italy). Pre-kinematic (early) LT blueschist conditions, consistent with lawsonite and glaucophane stability, are assumed on the basis of relict minerals enclosed in garnet cores. Syn-kinematic HT blueschist to eclogite conditions are deduced from the disappearance of lawsonite. Almandine-rich garnet - Mg-Fe chloritoid - glaucophane ± zoisite ± paragonite ± chlorite are the most common phases in glaucophanites, omphacite - garnet - rutile in eclogites. Post-kinematic, late-eclogite conditions are suggested by small recrystallized rims of garnet, growth of widespread unhomogeneous crossite and development of a new generation of chloritoid
Structural Features Of The Superfast-Spreading Crust From The Pacific Ocean: Evidence From Site 1256, Odp Leg 206
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