Relationships between tectonics and magmatism in a transtensive/transform setting: An example from Faial Island (Azores, Portugal)

Abstract

Research Article| January 01, 2014 Relationships between tectonics and magmatism in a transtensive/transform setting: An example from Faial Island (Azores, Portugal) D. Trippanera; D. Trippanera † 1Dipartimento di Scienze, Università Roma Tre, Largo S.L. Murialdo, 1, 00146 Rome, Italy †E-mail: [e-mail] Search for other works by this author on: GSW Google Scholar M. Porreca; M. Porreca 2Centro de Vulcanologia e Avaliação de Riscos Geológicos, Rua da Mãe de Deus, 9501-801 Ponta Delgada, Açores, Portugal3Istituto Nazionale di Geofisica e Vulcanologia (INGV), Via dell’Arcivescovado, 8, 67100 L’Aquila, Italy Search for other works by this author on: GSW Google Scholar J. Ruch; J. Ruch 1Dipartimento di Scienze, Università Roma Tre, Largo S.L. Murialdo, 1, 00146 Rome, Italy Search for other works by this author on: GSW Google Scholar A. Pimentel; A. Pimentel 2Centro de Vulcanologia e Avaliação de Riscos Geológicos, Rua da Mãe de Deus, 9501-801 Ponta Delgada, Açores, Portugal Search for other works by this author on: GSW Google Scholar V. Acocella; V. Acocella 1Dipartimento di Scienze, Università Roma Tre, Largo S.L. Murialdo, 1, 00146 Rome, Italy Search for other works by this author on: GSW Google Scholar J. Pacheco; J. Pacheco 2Centro de Vulcanologia e Avaliação de Riscos Geológicos, Rua da Mãe de Deus, 9501-801 Ponta Delgada, Açores, Portugal Search for other works by this author on: GSW Google Scholar M. Salvatore M. Salvatore 1Dipartimento di Scienze, Università Roma Tre, Largo S.L. Murialdo, 1, 00146 Rome, Italy Search for other works by this author on: GSW Google Scholar GSA Bulletin (2014) 126 (1-2): 164–181. https://doi.org/10.1130/B30758.1 Article history received: 05 Jul 2012 rev-recd: 09 Sep 2013 accepted: 17 Oct 2013 first online: 08 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation D. Trippanera, M. Porreca, J. Ruch, A. Pimentel, V. Acocella, J. Pacheco, M. Salvatore; Relationships between tectonics and magmatism in a transtensive/transform setting: An example from Faial Island (Azores, Portugal). GSA Bulletin 2014;; 126 (1-2): 164–181. doi: https://doi.org/10.1130/B30758.1 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 relationships between tectonics and hotspot-related magmatism in transform/transtensive settings are poorly known. The Azores archipelago, lying where the transform plate boundary between the Nubian and Eurasian plates meets the Mid-Atlantic Ridge, is a rare site to investigate these relationships. The distinct tectono-magmatic features of Faial make it the ideal island to focus the study. Here, we analyze the relationships between tectonics and magmatism, using remote-sensing, field, and paleomagnetic analyses. Dominant WNW-ESE–trending lineaments correspond to major faults with transtensive dextral motion and NE-SW opening, probably related to the nearby transtensive Terceira Rift. Most (∼60%) dikes, vent elongations, and alignments are parallel to this system. The lavas forming the basement of the distinctive WNW-ESE–trending Pedro Miguel graben strike parallel to the graben axis, dipping outward with a tilt consistent with that of paleomagnetic data. These lavas are dissected by the WNW-ESE–trending transtensive faults. Therefore, the graben consists of outward-tilted fault-bounded blocks, forming two opposite-verging dominoes. Its estimated stretching factor (β = 1.35) and mean extension rate (between 3.4 and 8.2 mm/yr) are similar or slightly larger than those of Terceira Rift, to the east. Part of the graben extension may be magma induced, via diking. We suggest that: (1) Faial, along with the nearby Pico Island, is a major locus of extension within the Azores, directly above the imaged hotspot; and (2) the Faial-Pico magmatic segment constitutes the offset, westward magmatic continuation of the Terceira Rift. The segment opening highlights the importance of extensional strain along magmatic transtensive plate boundaries. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.