Carbon dioxide generation and drawdown during active orogenesis of siliciclastic rocks in the Southern Alps, New Zealand

C.D.M. was supported by NERC CASE PhD studentship award NE/G524160/1 (GNS Science, NZ, CASE partner). D.A.H.T. acknowledges support from research grants NE/H012842/1 and NE/J022128/1 and a Royal Society Wolfson Research Merit Award (WM130051). S.C.C. was funded under GNS Science's “Impacts of Global Plate Tectonics in and around New Zealand Programme” (PGST Contract CO5X0203). J.C.A. was supported by NSF OCE1334758. We also thank Matthew Cooper, Andy Milton, Darryl Green and Lora Wingate for laboratory assistance. We thank Mike Bickle for editorial advice and comments, and reviews from two anonymous reviewers that improved this manuscript.Peer reviewedPublisher PD

Data report : major-element chemistry of Hole 896a glass

Ocean Drilling Program Hole 896A (1°13.01'N, 83°43.39'W) is in 3440 m of water east of the Galapagos Platform in the equatorial eastern Pacific Ocean. At this site in 5.9 Ma crust, basement rocks were recovered over the depth range of 195.1 meters below seafloor (mbsf) to 469 mbsf. These rocks are mostly pillow lavas, but massive flows, breccias and dikes are also present. Many of the lavas and flows have quenched glass on their exteriors, and breccias commonly contain glass. Glass was analyzed by electron microprobe in six laboratories as part of shore-based studies of the rocks. These analyses are collected here so that all the chemical analyses are available in one publication. The analyses are interpreted in individual publications elsewhere in this volume

Uplift and exposure of serpentinized massifs: Modeling differential serpentinite diapirism and exhumation of the Troodos Mantle Sequence, Cyprus

Serpentinized mantle peridotites form prominent mountains, including the highest elevations of the Troodos ophiolite in Cyprus (Mount Olympus, 1,952 m), but to date, only qualitative mechanisms have been proposed to explain the uplift of mantle rocks to high altitudes. Serpentinization reactions between mantle rocks and water result in profound changes to the rheology and physical properties of peridotites including significant density reduction (∼900 kg/m3). Field observations, density measurements, and isostatic uplift and erosional modeling provide new constraints on the contribution of serpentinization to the uplift of the Troodos Mantle Sequence. Different serpentinization styles have resulted in two distinct serpentinite domains with contrasting densities. Our modeling shows that the Troodos Mountains can form within the geologically constrained uplift time frame (∼5.5 Myr) exclusively through partial serpentinization reactions. We interpret the serpentinite domains as two nested diapirs that formed due to different extents of serpentinization and density reduction. Differential uplift and exhumation have decoupled the two serpentinite diapirs from the originally overlying ocean crustal rocks. Once at high altitudes the incursion of meteoric water reinforced coupled deformation-alteration-recrystallization processes in the shallow subsurface producing a localized low density completely serpentinized diapir. A second decoupling between the contrasting serpentinite diapirs results in localized differential uplift and exhumation, extruding deep materials to the east of Mount Olympus. Application of our modeling to other serpentinite massifs (e.g., St. Peter and St. Paul Rocks, New Idria, California) highlights the contribution of isostasy to the uplift of serpentinized massifs

Geological storage of CO2 within the oceanic crust by gravitational trapping

The rise of atmospheric carbon dioxide (CO2) principally due to the burning of fossil fuels is a key driver of anthropogenic climate change. Mitigation strategies include improved efficiency, using renewable energy, and capture and long-term sequestration of CO2. Most sequestration research considers CO2 injection into deep saline aquifers or depleted hydrocarbon reservoirs. Unconventional suggestions include CO2 storage in the porous volcanic lavas of uppermost oceanic crust. Here we test the feasibility of injecting CO2 into deep-sea basalts and identify sites where CO2 should be both physically and gravitationally trapped. We use global databases to estimate pressure and temperature, hence density of CO2 and seawater at the sediment-basement interface. At previously suggested sites on the Juan de Fuca Plate and in the eastern equatorial Pacific Ocean, CO2 is gravitationally unstable. However, we identify five sediment-covered regions where CO2 is denser than seawater, each sufficient for several centuries of anthropogenic CO2 emissions

Alteration and vein logs of ODP Holes 152-917A and 152-918D

This data report provides a systematic documentation of the low-temperature alteration associated with the formation of a volcanic-rifted margin by the quantification of alteration effects and vein mineralogy and distributions in basalts recovered on Leg 152 (Larsen, Saunders, Clift, et al., 1994, doi:10.2973/odp.proc.ir.152.1994). Basaltic rocks from Holes 917A and 918D have been investigated to provide a quantitative description of the extents of recrystallization and secondary mineral abundance resulting from low-temperature alteration and weathering. Only limited descriptions of alteration and secondary mineral distributions were undertaken on board ship during Leg 152, and the data presented here provide an essential complement to the shipboard logs of the limited amount of basalt recovered during Leg 163 from Sites 988, 989, and 990 (Duncan, Larsen, Allan, et al., 1996, doi:10.2973/odp.proc.ir.163.1996)