Channelling of hydrothermal fluids during the accretion and evolution of the upper oceanic crust: Sr isotope evidence from ODP Hole 1256D

Subsurface structure of a submarine hydrothermal system in ocean crust formed at the East Pacific Rise, ODP/IODP Site 1256

[1] ODP/IODP Hole 1256D penetrates an in situ section of ocean crust formed at the East Pacific Rise, through lavas and sheeted dikes and ∼100 m into plutonic rocks. We use mineralogy, oxygen isotopes, and fluid inclusions to understand hydrothermal processes. The lavas are slightly altered at low temperatures (<150°C) to phyllosilicates and iron oxyhydroxides, with a stepwise increase in grade...

crust: implications for the sources of metals

10 Volcanogenic Massive Sulphide (VMS) deposits are commonly enriched in Cu, Zn and 11 Pb and can also be variably enriched in Au, As, Sb, Se and Te. The behaviour of these elements 12 during hydrothermal alteration of the oceanic crust is not well known. Ocean Drilling Program 13 (ODP) Hole 1256D penetrates a complete in-situ section of the upper oceanic crust providing a 14 unique sample suit...

Hydrothermal cooling of the ocean crust: Insights from ODP Hole 1256D

Oxygen isotope composition of a section of lower oceanic crust, ODP Hole 735B

[1] The oxygen and hydrogen isotope compositions of vein minerals and dO values of 64 whole rocks from the deeper kilometer of the 1.5 km lower crustal section of ODP Hole 735B in the SW Indian Ocean were analyzed in order to investigate seawater penetration into and reaction with the lower oceanic crust. Vein amphiboles have dD values of 35 to 65%, indicating formation from seawater fluids and...

Iodp Expedition 309: Superfast Spreading Rate Crust 2 Site 1256 Summary

Expedition 309, “Superfast Spreading Rate Crust 2,” successfully deepened Hole 1256D (6.736°N, 91.934°W) by 503 m to a total depth of 1255.1 meters below seafloor (mbsf) or 1005.1 meters subbasement. The average rate of core recovery for the expedition was 36%. Much higher rates of recovery were experienced in the lowermost section of the hole (~70% average below 1200 mbsf). At the end of Exped...