1036 10 MARCH 2017 • VOL 355 ISSUE 6329 and Bachan developed a model of seawater chemistry and pH over time scales exceeding ~100 million years. Their highly robust probabilistic history of seawater pH and chemistry reflects evolving properties of Earth’s atmosphere, oceans, and crust. Seawater pH increased from early Archean values of ~6.5 to 7.0 to more recent values of ~7.5 to 9.0 mostly as ...

Deep-sea oceanic crust constitutes the largest region of the earth's surface. Accumulating evidence suggests that unique microbial communities are supported by iron cycling processes, particularly in the young (<10 million-year old), cool (<25°C) subsurface oceanic crust. To test this hypothesis, we investigated the microbial abundance, diversity, and metabolic potentials in the sediment-buried...

Bulk permeability was determined from drillstring packer measurements in ODP Hole 801C in Jurassic oceanic crust in the western Pacific. The values average 8 x 10 -14 m 2 over 93 m of open hole, or 4 X 10 -13 m 2 if the permeable interval is confined to an 18 m thick hydrothermal zone within oceanic basement. These values are about 1-10 times higher than those reported for the upper sections of...

During ODP Leg 111, the drillship JOIDES Resolution returned to DSDP Hole 504B, on the south flank of the Costa Rica Rift. The main objective of Leg 111 was the study of the physical and chemical structure of young oceanic crust in the deepest hole yet drilled into the oceanic crust. In addition to the drilling of an additional 212.3 m into the massive units of Layer 2C, Leg 111 provided the op...

The recent recognition of fungi in the oceanic igneous crust challenges the understanding of this environment as being exclusively prokaryotic and forces reconsiderations of the ecology of the deep biosphere. Anoxic provinces in the igneous crust are abundant and increase with age and depth of the crust. The presence of anaerobic fungi in deep-sea sediments and on the seafloor introduces a type...

During Leg 185 two deep-water sites will be drilled, one seaward of the Mariana Trench (Ocean Drilling Program Hole 801C) and one seaward of the Izu-Bonin Trench (Site BON8A). The primary objectives are to investigate sediment subduction along this arc-trench system and to characterize the chemical fluxes during alteration of the oceanic crust. Despite the simple setting and shared subducting p...