Internal structure and emplacement of the Papoose Flat pluton: An integrated structural, petrographic, and magnetic susceptibility study

Research Article| August 01, 2001 Internal structure and emplacement of the Papoose Flat pluton: An integrated structural, petrographic, and magnetic susceptibility study Michel de Saint-Blanquat; Michel de Saint-Blanquat 1Centre National de la Recherche Scientifique–Unité Mixte de Recherche 5563, Mécanismes de Transfert en Géologie, Observatoire Midi-Pyrénées–Université Paul-Sabatier, 38 rue des 36 Ponts, F-31400 Toulouse, France Search for other works by this author on: GSW Google Scholar Richard D. Law; Richard D. Law 2Department of Geological Sciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061-0420, USA Search for other works by this author on: GSW Google Scholar Jean-Luc Bouchez; Jean-Luc Bouchez 3Unité Mixte de Recherche, 5563 Mécanismes de Transfert en Géologie, Observatoire Midi-Pyrénées–Université Paul-Sabatier, 38 rue des 36 Ponts, F-31400 Toulouse, France Search for other works by this author on: GSW Google Scholar Sven S. Morgan Sven S. Morgan 4Department of Geology, Central Michigan University, Mount Pleasant, Michigan 48859, USA Search for other works by this author on: GSW Google Scholar Author and Article Information Michel de Saint-Blanquat 1Centre National de la Recherche Scientifique–Unité Mixte de Recherche 5563, Mécanismes de Transfert en Géologie, Observatoire Midi-Pyrénées–Université Paul-Sabatier, 38 rue des 36 Ponts, F-31400 Toulouse, France Richard D. Law 2Department of Geological Sciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061-0420, USA Jean-Luc Bouchez 3Unité Mixte de Recherche, 5563 Mécanismes de Transfert en Géologie, Observatoire Midi-Pyrénées–Université Paul-Sabatier, 38 rue des 36 Ponts, F-31400 Toulouse, France Sven S. Morgan 4Department of Geology, Central Michigan University, Mount Pleasant, Michigan 48859, USA Publisher: Geological Society of America Received: 12 Nov 1999 Revision Received: 13 Jun 2000 Accepted: 25 Oct 2000 First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (2001) 113 (8): 976–995. https://doi.org/10.1130/0016-7606(2001)113<0976:ISAEOT>2.0.CO;2 Article history Received: 12 Nov 1999 Revision Received: 13 Jun 2000 Accepted: 25 Oct 2000 First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Michel de Saint-Blanquat, Richard D. Law, Jean-Luc Bouchez, Sven S. Morgan; Internal structure and emplacement of the Papoose Flat pluton: An integrated structural, petrographic, and magnetic susceptibility study. GSA Bulletin 2001;; 113 (8): 976–995. doi: https://doi.org/10.1130/0016-7606(2001)113<0976:ISAEOT>2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract The Papoose Flat pluton of eastern California is commonly cited in the geologic literature as a classic example of a "forcibly" emplaced pluton, although the relative importance attributed to magmatic versus tectonic processes in controlling the structural evolution of the pluton has been controversial. Reexamination of this Late Cretaceous (83 Ma) pluton, using a combination of new structural, petrographic, microstructural, and anisotropy of magnetic susceptibility (AMS) data on the pluton–wall-rock system, has shown that the pluton is an inclined and internally zoned tabular structure, assembled by forcible intrusion of successive pulses of magma at a crustal depth of 12–15 km. Initial pluton formation involved magma ascent in a vertical west- northwest–striking feeder dike, which was arrested at a stratigraphically controlled mechanical discontinuity in the overlying Cambrian metasedimentary rocks, leading to formation of a southwest-dipping sill. Subsequent sill inflation, accompanied by horizontal infilling from the feeder dike at the base of the sill, resulted in deformation and vertical translation of previously emplaced magma pulses and local raising of the sill roof, facilitated by thermal weakening as the wall-rock temperatures progressively rose during emplacement of successive magma pulses. Cooling from the roof of the pluton downward resulted in cessation of vertical inflation on the west side of the pluton and promoted lateral expansion toward the northeast and floor depression below the eastern part of the pluton.We have been unable to document any regional-scale structures (e.g., of equivalence to similar-age synplutonic strike-slip shear zones in the Sierra Nevada batholith to the west) that may have controlled emplacement of the Papoose Flat pluton. However, this fact does not preclude the likelihood that the country rocks were subjected to a regional deviatoric stress field at this time; indeed, tectonic overpressuring was probably essential for producing sufficiently high magma pressures for laccolith formation at this midcrustal level. Simple thermal modeling, using microstructural and thermobarometric data, indicates that the total duration of emplacement of the pluton did not exceed 30 000 yr. This rapid emplacement rate may explain why the pluton appears to be anorogenic even though it was emplaced during a period of regional- scale deformation. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.