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Young rifts are shaped by combined tectonic and surface processes and climate, yet few records exist to evaluate the interplay of these processes over an extended period of early rift-basin development. Here, we present the longest and highest resolution record of sediment flux and paleoenvironmental changes when a young rift connects to the global oceans. New results from International Ocean Discovery Program (IODP) Expedition 381 in the Corinth Rift show 10s–100s of kyr cyclic variations in basin paleoenvironment as eustatic sea level fluctuated with respect to sills bounding this semi-isolated basin, and reveal substantial corresponding changes in the volume and character of sediment delivered into the rift. During interglacials, when the basin was marine, sedimentation rates were lower (excepting the Holocene), and bioturbation and organic carbon concentration higher. During glacials, the basin was isolated from the ocean, and sedimentation rates were higher (~2–7 times those in interglacials). We infer that reduced vegetation cover during glacials drove higher sediment flux from the rift flanks. These orbital-timescale changes in rate and type of basin infill will likely influence early rift sedimentary and faulting processes, potentially including syn-rift stratigraphy, sediment burial rates, and organic carbon flux and preservation on deep continental margins worldwide.

The STAT1 transcription factor is organized into several highly conserved domains, each of which has been assigned a function with the exception of the linker domain. We previously characterized a mutant in the linker domain of STAT1 that gave normal DNA binding using a standard probe in an electrophoretic mobility assay but failed to activate transcription in response to interferon ␥. We now report the mechanistic basis for the inactivity of this STAT1(K544A/E545A) mutant. Rather than failing to attract transcriptional coactivators, the STAT1(K544A/E545A) mutant has a subtle biophysical defect, which prevents accumulation of the activated protein on chromatin in vivo: the mutant has comparable K d with greatly increased k off for DNA binding. The increase in both on-rate and off-rate of DNA binding results in a substantially reduced residence time of STAT1(K544A/E545A) on STAT binding sites. We find a similar correlation between off-rate and transcriptional potency for STAT1(N460A), which bears a mutation in the DNA binding domain. These results yield insight into the rate of complex assembly involving STAT1 that leads to transcriptional stimulation.

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[1] This study presents borehole geophysical data and sidewall core chemistry from the Wallula Pilot Sequestration Project in the Columbia River flood basalt. The wireline logging data were reprocessed, core-calibrated and interpreted in the framework of reservoir and seal characterization for carbon dioxide storage. Particular attention is paid to the capabilities and limitations of borehole spectroscopy for chemical characterization of basalt. Neutron capture spectroscopy logging is shown to provide accurate concentrations for up to 8 major and minor elements but has limited sensitivity to natural alteration in fresh-water basaltic reservoirs. The Wallula borehole intersected 26 flows from 7 members of the Grande Ronde formation. The logging data demonstrate a cyclic pattern of sequential basalt flows with alternating porous flow tops (potential reservoirs) and massive flow interiors (potential caprock). The log-derived apparent porosity is extremely high in the flow tops (20-45%), and considerably overestimates effective porosity obtained from hydraulic testing. The flow interiors are characterized by low apparent porosity (0-8%) but appear pervasively fractured in borehole images. Electrical resistivity images show diverse volcanic textures and provide an excellent tool for fracture analysis, but neither fracture density nor log-derived porosity uniquely correlate with hydraulic properties of the Grande Ronde formation. While porous flow tops in these deep flood basalts may offer reservoirs with high mineralization rates, long leakage migration paths, and thick sections of caprock for CO 2 storage, a more extensive multiwell characterization would be necessary to assess lateral variations and establish sequestration capacity in this reservoir.