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#shearzone

💧🌏 Greg CocksGregCocks@techhub.social
2025-01-24

Deep Beneath California's Sierra Nevada, Earth's Lithosphere May Be Peeling Away
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phys.org/news/2025-01-deep-ben <-- shared technical article
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doi.org/10.1029/2024GL111290 <-- shared paper
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#GIS #spatial #mapping #geology #lithosphere #California #SierraNevada #continentalcrust #crust #mantle #foundering #remotesensing #geophysics #geophysical #earthquake #spatialanalysis #spatiotemporal #structuralgeology #earthquake #seismic #seismology #Moho #platetectonics #tectonics #shearzone #faults #faulting #seismicity #model #modeling #3dmodel

photo - portion of the Sierra Nevadas, rocky landscapemaps - results from receiver function analysis, Sierra Nevada, Californiacross-section schematic - Perspective view of imaged shear layer in geographic context for the central and southern Sierramap - Study area. Seismic stations (triangles, dark gray = permanent, light gray = temporary), seismicity with 40+ km depth from USGS ComCat catalog 2006–2023 (blue circles); thin black rectangle is extent of Figure 2. Faults in light gray. Small inset map shows regional context; main figure area outlined. GO-Gorda plate; MTJ-Mendocino triple junction; PA-Pacific plate; YP-Yosemite National Park; FR-Fresno; MW-Mt. Whitney; RC-Ridgecrest. Blue station labels mark examples appearing in later figures.
Sisyphus with a Hatlouisffourie@c.im
2022-12-14

This is a very interesting photo. Take on the beach at Ballyliffin, Donegal, it shows the contact between the Termon Formation in the foreground and the Slieve Tooey quartzite Formation on the background. The Termon consists of pellitic schists, and the contact between the 2 is define by a fault, with the top of the older Slieve Tooey being sheered as well.

Both formations are part of the Argyll Group, the middle group of the Neoproterozoic Dalradian.

And to crown it off, very near the actual contact, in the center of the photo, we have a Rock pipit posing.

#geology #rocks #shearzone #fault #neoproterozoic #proterozoic #quartzite #pellite #birds #birding #birdwatching #birdphotography #pipit #rockpipit #irishbirds #birdsofireland #irishgeology

The photo shows 2 rock formations resting at a 30°angle approximately (higher on the left of the photo, which is also roughly south). The dip of the rock plane is approximately northwest. In the foreground the rocks are very sheared, apart from an eroded part in the very foreground which contains some sea water and a bit of moss(?). The colour in the foreground is brownish grey, while on the background it is beige-ish to grey. The rocks in the background are eless sheared than the lnes in the foreground. Close to the contact between the 2 formations is a little pipit, light brownish in colour with dark brown stripes on the breast, sitting erect and looking north.

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