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1. Heterogeneous Crustal Structure of the Hikurangi Plateau Revealed by SHIRE Seismic Data: Origin and Implications for Plate Boundary Tectonics

   https://doi.org/10.1029/2023GL105674  

   Bassett, Dan; Fujie, Gou; Kodaira, Shuichi; Arai, Ryuta; Yamamoto, Yojiro; Henrys, Stuart; Barker, Dan; Gase, Andrew; van Avendonk, Harm; Bangs, Nathan; et al (November 2023, Geophysical Research Letters)

   Abstract Marine multichannel and wide‐angle seismic data constrain the distribution of seamounts, sediment cover sequence and crustal structure along a 460 km margin‐parallel transect of the Hikurangi Plateau. Seismic reflection data reveals five seamount up‐to 4.5 km high and 35–75 km wide, with heterogeneous internal velocity structure. Sediment cover decreases south‐to‐north from ∼4.5 km to ∼1–2 km. The Hikurangi Plateau crust (V_P5.5–7.5 km/s) is 11 ± 1 km thick in the south, but thins by 3–4 km further north (∼7–8 km). Gravity models constructed along two seismic lines show the reduction in crustal thickness persists further east, coinciding with a bathymetric scarp. Gravity data suggest the transition in crustal thickness may reflect spatial variability in deformation and lithospheric extension associated with plateau breakup. Variability in the thickness of subducting crust may contribute to differences in megathrust geometry, upper‐plate stress state and high‐rates of contraction and uplift along the southern Hikurangi margin. 

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2. Crust and Mantle Flow From Central Tibetan Plateau to the Indo‐Burma Subduction Zone

   https://doi.org/10.1029/2023JB027540  

   Timsina, Prakash; Hearn, Thomas_M; Ni, James_F (October 2024, Journal of Geophysical Research: Solid Earth)

   Abstract The extremely oblique Indo‐Burma subduction zone exhibits dextral strike‐slip faulting along the Sagaing, Kabaw, and Churachandpur‐Mao Faults as well as east‐west shortening between the Sagaing Fault and Bengal Basin. Through regional stress analysis, considering areas from central Tibet, around the eastern Himalaya Syntaxis, to Burma, it has been determined that the principal compressive stress directions align with the principal strain rates. The northeast‐southwest oriented compressive stress direction from the western Shan Plateau continues into Burma. Notably, P axes align with the topographic gradients, and T axes are sub‐parallel to the topographic contours in the Shan Plateau region south of 27°N. These stress patterns are consistent with a gravitational potential energy induced crustal and mantle flow. The alignment of the fast shear wave with the maximum strain rate and the colinear NW‐SE to E‐W fast direction of the SKS wave and T axis determined from focal mechanisms in the Shan Plateau suggest that the mantle lithosphere deforms in concert with the crust. We suggest crust and mantle flow south of the Red River Fault has resulted in widening of the lithosphere in the Shan Plateau in an east‐west direction. Therefore, the Sagaing Fault has bowed approximately 50–100 km westward if we assume that the Sagaing Fault was originally straight. Our results of regional stress inversion are consistent with late Miocene to present E‐W shortening in the Indo‐Burma subduction zone resulting from the release of gravitational potential energy from the central Tibetan Plateau. 

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3. Whole-lithosphere shear during oblique rifting

   https://doi.org/10.1130/G49603.1  

   Lutz, Brandon M.; Axen, Gary J.; van Wijk, Jolante W.; Phillips, Fred M. (December 2021, Geology)

   Abstract Processes controlling the formation of continental whole-lithosphere shear zones are debated, but their existence requires that the lithosphere is mechanically coupled from base to top. We document the formation of a dextral, whole-lithosphere shear zone in the Death Valley region (DVR), southwest United States. Dextral deflections of depth gradients in the lithosphere-asthenosphere boundary and Moho are stacked vertically, defining a 20–50-km-wide, lower lithospheric shear zone with ~60 km of shear. These deflections underlie an upper-crustal fault zone that accrued ~60 km of dextral slip since ca. 8–7 Ma, when we infer that whole-lithosphere shear began. This dextral offset is less than net dextral offset on the upper-crustal fault zone (~90 km, ca. 13–0 Ma) and total upper-crustal extension (~250 km, ca. 16–0 Ma). We show that, before ca. 8–7 Ma, weak middle crust decoupled upper-crustal deformation from deformation in the lower crust and mantle lithosphere. Between 16 and 7 Ma, detachment slip thinned, uplifted, cooled, and thus strengthened the middle crust, which is exposed in metamorphic core complexes collocated with the whole-lithosphere shear zone. Midcrustal strengthening coupled the layered lithosphere vertically and therefore enabled whole-lithosphere dextral shear. Where thick crust exists (as in pre–16 Ma DVR), midcrustal strengthening is probably a necessary condition for whole-lithosphere shear. 

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4. September 2017 Phase Space Density Observations - T89

   https://doi.org/10.5281/zenodo.7293955  

   Staples, Frances; Kellerman, Adam (January 2022, Zenodo)

   Archived data for the manuscript “Differentiating Between Simultaneous Loss Drivers in Earth’s Outer Radiation Belt: Multi-Dimensional Phase Space Density Analysis”  Staples et al., submitted to Geophysical Research Letters 2022.</p> These files contain multi-mission phase space density measurements including, Van Allen Probes, GOES 13, 14, 15, GPS, MMS, and THEMIS, computed in adiabatic coordinates. All data is from September 2017. For detailed description of the method used in the computation of this data, see section 2.1 of the submitted manuscript. The THEMIS, Van Allen Probe, MMS, and GOES data used in computations is publicly available via http://cdaweb.gsfc.nasa.gov  The GPS data is available via https://www.ngdc.noaa.gov/stp/space-weather/satellite-data/satellite-systems/gps/</p> FILES:</p> 'psd_intp_T89_20170901-20170930_allsc.cdf'</p> 'psd_intp_T89_20170901-20170930_rbsp-b.cdf'</p> DATA OWNER: Adam Kellerman DATA PREPERATION: Frances Staples</p> CONTACT: Adam Kellerman: akellerman@epss.ucla.edu Frances Staples: frances.staples@ucl.ac.uk</p> FS was supported by NASA grants 80NSSC20K1402 and NSF grant 2149782. ACK acknowledges support from NASA grants 80NSSC20K1402 and 80NSSC20K1281, and NSF grant 2149782. 

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5. Radar Reflectivity at Whillans Ice Plain

   https://doi.org/10.5281/zenodo.11201199  

   Hills, Benjamin; Siegfried, Matthew (January 2024, Zenodo)

   {"Abstract":["This is an extracted data product for radar bed reflectivity from Whillans Ice Plain, West Antarctica. The original data are hosted by the Center for Remote Sensing of Ice Sheets (CReSIS; see associated citation below). The files here can be recalculate and are meant to be used within a set of computational notebooks here:https://doi.org/10.5281/zenodo.10859135\n\nThere are two csv files included here, each structured as a Pandas dataframe. You can load them in Python like:df = pd.read_csv('./Picked_Bed_Power.csv')\n\nThe first file, 'Picked_Bed_Power.csv' is the raw, uncorrected power from the radar image at the bed pick provided by CReSIS. There are also other useful variables for georeferencing, flight attributes, etc.\n\nThe second file, 'Processed_Reflectivity.csv' is processed from the first file. Processing includes: 1) a spreading correction; 2) an attenuation correction; and, 3) a power adjustment flight days based on compared power at crossover points. This file also has identifiers for regions including "grounded ice", "ungrounded ice", and "subglacial lakes"."]} 

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