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Soil salinity negatively impacts the productivity and profitability of western San Joaquin Valley (WSJV) farmland. Many factors, including drought, climate change, reduced water allocations, and land-use changes could worsen salinity conditions there, and in other agricultural lands in the state. Mapping soil salinity at regional and state levels is essential for identifying drivers and trends in agricultural soil salinity, and for developing mitigation strategies, but traditional soil sampling for salinity does not allow for accurate large-scale mapping. We tested remote-sensing modeling to map root zone soil salinity for farmland in the WSJV. According to our map, 0.78 million acres are salt affected (i.e., ECe > 4 dS/m), which represents 45% of the mapped farmland; 30% of that acreage is strongly or extremely saline. Independent validations of the remote-sensing estimations indicated acceptable to excellent correspondences, except in areas of low salinity and high soil heterogeneity. Remote sensing is a viable tool for helping landowners make decisions about land use and also for helping water districts and state agencies develop salinity mitigation strategies.

Convergence and shallow subduction of the Yakutat microplate beneath North America has shaped the Pamplona zone fold and thrust belt in the northeastern Alaska subduction zone. Here, convergent tectonics and glaciomarine sedimentary processes have created patterns of deformation and deposition recorded by a shallow sedimentary sequence with varying fluid pressure, compaction, and fault activity. If the record of ice sheet advance is preserved on the seafloor and in the underlying sediments then bathymetric evidence of glaciomarine processes should overlap with evidence of overpressure, such as low velocity zones in the shallow sediments. In this study, we present a velocity model through the Bering trough as well as regional drainage shape characteristics. We use streamer tomography on a seismic survey from the St. Elias Erosion and Tectonics Project (STEEP) to determine a velocity model. We further inform our interpretation using physical properties relationships developed with data from core samples (IODP Expedition 341) taken near the seismic line. To document drainage morphology, we use smooth sheet bathymetry to identify a drainage network and query profile shapes at well distributed locations; where profile shape is determined by fit with a power function. Initial results suggest overlap between u-shaped drainage profiles towards the SE end of the Bering trough and low-velocity shallow sediments NE of the shelf break. In part, because this overlap occurs within the mapped extent of the last glacial maximum, we find our tomography results consistent with buildup of overpressure due to glacially driven loading of highly saturated sediments. [ABSTRACT FROM AUTHOR]

The Picuris-Pecos fault has been shown to have about 40 km of observed dextral strike slip separation due to to various contributions of Laramide, Pennsylvanian, and/or Precambrian age fault slip and reactivation (e.g. Cather et al., 2000; Erslev et al., 2004; Sanders et al., 2006). Based on the regional cooling history, deformation in the Precambrian would likely be ductile while more recent deformation would be dominated by brittle features. Original field workers interpreted the main phase of deformation along the Picuris-Pecos to be Precambrian, and interpreted the observed deflection of folded units near the fault to be ductile and relatively high temperature. Other more recent studies have shown large offsets in Pennsylvanian rocks, and have proposed the main phase of dextral separation to have occurred during the Ancestral Rocky Mountain orogeny. Petrographic and structural analysis by Luther et al., 2012 proposed that ~2.5 km of observed refolding in the Hondo syncline was likely at brittle-ductile conditions and predated, or formed during, the inception of dextral shear possibly associated with Grenville age activities. In order to evaluate hypotheses proposing brittle or ductile deformation we present a pilot textural study of the Picuris-Pecos fault at Dalton Canyon based on field measurements such as foliations, and petrographic analysis of oriented thin sections collected in the area. We approach ductile deformation using a spatial analysis of foliations in the McClure quadrangle to quantify orientation near the fault, and we quantify brittle deformation by comparing grain size distributions in cataclasite samples near the fault zone. [ABSTRACT FROM AUTHOR]

In the last decades research has shown that climate activity can be an important component of large scale tectonics. Glacial erosion and deposition, forced by climate patterns, affect mass balance in large-scale tectonically active regions as well as offshore depositional basins. One ideal natural laboratory to study these climate-tectonic interactions is offshore glacial-marine deposits in SE Alaska where an offshore accretionary wedge records glacial and marine sedimentation as well as faulting. This location is ideal because the offshore depositional basin is near the onshore sediment source which facilitates a short time between erosion and deposition as well as a relatively closed system from source to basin. Thanks to previous research efforts there is extensive data including sediment core, well log measurements, bathymetry, and offshore seismic reflection surveys available to aide in the interpretation of climate- linked glacial activity and fault activity. Detailed stratigraphic and structural interpretation of seismic reflection lines collected off the coast of SE Alaska allow for sequence interpretation of fault activity, glacial deposition, and climate change. Interpretation of sedimentation patterns with special focus on extent and style of glacial sedimentation and fault activity link these processes in space and time. Applied spatial-statistics provides a quantitative link between glacial activity and faulting by testing for shape similarity and proximity of related geologic features. [ABSTRACT FROM AUTHOR]