Editing Basin and Range Province (section)

===Tectonics===
[[File:MtMoriahNV.jpg|thumb|[[Snake Range]]]]
The tectonic mechanisms responsible for lithospheric extension in the Basin and Range province are controversial, and several competing hypotheses attempt to explain them. Key events preceding Basin and Range extension in the western United States include a long period of compression due to the [[subduction]] of the [[Farallon plate]] under the west coast of the North American continental plate which stimulated the thickening of the crust. Most of the pertinent tectonic plate movement associated with the province occurred in the [[Neogene]] period (23.03-2.58 million years ago) and continues to the present. By the Early [[Miocene]] sub-epoch (23.03-15.97 million years ago), much of the Farallon plate had been consumed, and the [[seafloor spreading ridge]] that separated the Farallon plate from the [[Pacific plate]] ([[Pacific-Farallon Ridge]]) approached North America.<ref name=Riney>{{cite web|last=Riney|first=Brad|url=http://www.oceanoasis.org/fieldguide/geology1.html|archive-url=https://web.archive.org/web/20110102140209/http://www.oceanoasis.org/fieldguide/geology1.html|archive-date=2011-01-02|title=Plate Tectonics|work=Ocean Oasis Field Guide|publisher=San Diego Natural History Museum|year=2000|access-date=5 Dec 2010}}</ref> In the Middle [[Miocene]] (15.97-11.63 million years ago), the Pacific-Farallon Ridge was subducted beneath North America ending [[subduction]] along this part of the Pacific margin; however, the Farallon plate continued to subduct into the [[Earth's mantle|mantle]].<ref name=Riney/> The movement at this boundary divided the Pacific-Farallon Ridge and spawned the [[San Andreas Fault|San Andreas]] [[transform fault]], generating an oblique [[strike-slip]] component.<ref>{{cite web|url=http://geology.isu.edu/Digital_Geology_Idaho/Module9/mod9.htm|work=Digital Geology of Idaho|title=Basin and Range Province – Tertiary Extension|access-date=5 Dec 2010|archive-date=11 September 2019|archive-url=https://web.archive.org/web/20190911200732/http://geology.isu.edu/Digital_Geology_Idaho/Module9/mod9.htm|url-status=dead}}</ref> Today, the Pacific plate moves north-westward relative to North America, a configuration which has given rise to increased shearing along the [[continental margin]].<ref name=Riney/>

The tectonic activity responsible for the extension in the Basin and Range is a complex and controversial issue among the geoscience community. The most accepted hypothesis suggests that crustal [[Shear (geology)|shearing]] associated with the [[San Andreas Fault]] caused spontaneous extensional faulting similar to that seen in the Great Basin.<ref name=Stanley>{{cite book|last=Stanley|first=SM|year=2005|title=Earth system history|location=New York|publisher=Freeman}}</ref> However, plate movement alone does not account for the high elevation of the Basin and Range region.<ref name=Stanley/> The western United States is a region of high [[heat transfer|heat flow]] which lowers the density of the lithosphere and stimulates [[isostasy|isostatic]] [[Uplift (geology)|uplift]] as a consequence.<ref>{{cite web|archive-url=https://web.archive.org/web/20101031185845/http://www.enotes.com/earth-science/basin-range-topography|url=http://www.enotes.com/earth-science/basin-range-topography|archive-date=2010-10-31|title=Basin and Range Topography|work=World of Earth Science|editor-first1=Lee|editor-last1=Lerner|editor-first2=Brenda Wilmoth|editor-last2=Lerner|first=Gale|last=Cengage|year=2003|publisher=eNotes.com|access-date=5 Dec 2010}}</ref> Lithospheric regions characterized by elevated heat flow are weak and extensional deformation can occur over a broad region. Basin and Range extension is therefore thought to be unrelated to the kind of extension produced by [[mantle convection|mantle upwelling]] which may cause narrow rift zones, such as those of the [[Afar triple junction]].<ref>{{citation|last=Stern|first=Robert J|type=Class Notes|title=Rifts|work=Physics and Chemistry of the Solid Earth|publisher=University of Texas at Dallas|location=Dallas, Texas|date=2010-09-01}}</ref> Geologic processes that elevate heat flow are varied, however some researchers suggest that heat generated at a subduction zone is transferred to the overriding plate as subduction proceeds. Fluids along fault zones then transfer heat vertically through the crust.<ref>{{cite journal|first1=Makoto|last1=Yamano|first2=Masataka|last2=Kinoshita|first3=Shusaku|last3=Goto|title=High heat flow anomalies on an old oceanic plate observed seaward of the Japan Trench|journal=International Journal of Earth Sciences|year=2008|volume=97|issue=2|pages=345–352|doi=10.1007/s00531-007-0280-1|bibcode=2008IJEaS..97..345Y|s2cid=129417881}}</ref> This model has led to increasing interest in [[Geothermal gradient|geothermal systems]] in the Basin and Range, and requires consideration of the continued influence of the fully subducted Farallon plate in the extension responsible for the Basin and Range Province.