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Marine Transform Faults and Fracture Zones: a Joint Perspective Integrating Seismicity, Fluid Flow and Life

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Marine Transform Faults and Fracture Zones: a Joint Perspective Integrating Seismicity, Fluid Flow and Life feart-07-00039 March 15, 2019 Time: 16:15 # 1 REVIEW published: 19 March 2019 doi: 10.3389/feart.2019.00039 Marine Transform Faults and Fracture Zones: A Joint Perspective Integrating Seismicity, Fluid Flow and Life Christian Hensen1*, Joao C. Duarte2, Paola Vannucchi3,4, Adriano Mazzini5, Mark A. Lever6, Pedro Terrinha2,7, Louis Géli8, Pierre Henry9, Heinrich Villinger10, Jason Morgan3, Mark Schmidt1, Marc-André Gutscher11, Rafael Bartolome12, Yama Tomonaga13, Alina Polonia14, Eulàlia Gràcia12, Umberta Tinivella15, Matteo Lupi16, M. Namık Çagatay˘ 17, Marcus Elvert18, Dimitris Sakellariou19, Luis Matias2, Rolf Kipfer13, 19 8 1 20 Edited by: Aristomenis P. Karageorgis , Livio Ruffine , Volker Liebetrau , Catherine Pierre , 1 2,7 14 1 2,7 Alessandro Tibaldi, Christopher Schmidt , Luis Batista , Luca Gasperini , Ewa Burwicz , Marta Neres University of Milano-Bicocca, Italy and Marianne Nuzzo21 Reviewed by: 1 GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany, 2 Instituto Dom Luiz (IDL), Faculdade de Ciências da Shinsuke Kawagucci, Universidade de Lisboa, Lisbon, Portugal, 3 Earth Sciences Department, Royal Holloway, University of London, Egham, Japan Agency for Marine-Earth United Kingdom, 4 Dipartimento di Scienze della Terra, Università di Firenze, Firenze, Italy, 5 Centre for Earth Evolution Science and Technology, Japan and Dynamics (CEED), University of Oslo, Oslo, Norway, 6 Department of Environmental Systems Science, ETH Zürich, Wolfgang Rabbel, Zurich, Switzerland, 7 IPMA- Portuguese Institute for Atmosphere and Ocean, Lisbon, Portugal, 8 Institut Français University of Kiel, Germany de Recherche pour l’Exploitation de la Mer (IFREMER), Département Ressources Physiques et Ecosystèmes de Fond *Correspondence: de Mer, Unité des Géosciences Marines, Plouzané, France, 9 Aix Marseille Univ, CNRS, IRD, INRA, Coll France, CEREGE, Christian Hensen Aix-en-Provence, France, 10 Department of Geosciences, University of Bremen, Bremen, Germany, 11 CNRS, IUEM, [email protected] Laboratoire Géosciences Océan, University of Western Brittany, Brest, France, 12 Barcelona-CSI, Institut de Ciències del Mar (CSIC), Barcelona, Spain, 13 Eawag, Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland, 14 15 Specialty section: CNR, Institute of Marine Sciences (ISMAR), Bologna, Italy, Istituto Nazionale di Oceanografia e di Geofisica 16 17 This article was submitted to Sperimentale, Trieste, Italy, Department of Earth Sciences, University of Geneva, Geneva, Switzerland, EMCOL ˙ 18 Structural Geology and Tectonics, and Faculty of Mining, Department of Geological Engineering, Istanbul Technical University, Istanbul, Turkey, MARUM – 19 a section of the journal Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany, Hellenic Centre for Marine Research, 20 21 Frontiers in Earth Science Institute of Oceanography, Anavyssos, Greece, LOCEAN, UPMC, Sorbonne Université, Paris, France, Integrated Geochemical Interpretation Ltd., The Granary, Hallsannery, Bideford, United Kingdom Received: 22 November 2018 Accepted: 18 February 2019 Published: 19 March 2019 Marine transform faults and associated fracture zones (MTFFZs) cover vast stretches Citation: of the ocean floor, where they play a key role in plate tectonics, accommodating the Hensen C, Duarte JC, lateral movement of tectonic plates and allowing connections between ridges and Vannucchi P, Mazzini A, Lever MA, Terrinha P, Géli L, Henry P, Villinger H, trenches. Together with the continental counterparts of MTFFZs, these structures also Morgan J, Schmidt M, Gutscher M-A, pose a risk to human societies as they can generate high magnitude earthquakes Bartolome R, Tomonaga Y, Polonia A, Gràcia E, Tinivella U, Lupi M, and trigger tsunamis. Historical examples are the Sumatra-Wharton Basin Earthquake Çagatay˘ MN, Elvert M, Sakellariou D, in 2012 (M8.6) and the Atlantic Gloria Fault Earthquake in 1941 (M8.4). Earthquakes Matias L, Kipfer R, Karageorgis AP, at MTFFZs furthermore open and sustain pathways for fluid flow triggering reactions Ruffine L, Liebetrau V, Pierre C, Schmidt C, Batista L, Gasperini L, with the host rocks that may permanently change the rheological properties of the Burwicz E, Neres M and Nuzzo M oceanic lithosphere. In fact, they may act as conduits mediating vertical fluid flow (2019) Marine Transform Faults and Fracture Zones: A Joint and leading to elemental exchanges between Earth’s mantle and overlying sediments. Perspective Integrating Seismicity, Chemicals transported upward in MTFFZs include energy substrates, such as H2 and Fluid Flow and Life. volatile hydrocarbons, which then sustain chemosynthetic, microbial ecosystems at and Front. Earth Sci. 7:39. doi: 10.3389/feart.2019.00039 below the seafloor. Moreover, up- or downwelling of fluids within the complex system Frontiers in Earth Science | www.frontiersin.org 1 March 2019 | Volume 7 | Article 39 feart-07-00039 March 15, 2019 Time: 16:15 # 2 Hensen et al. MTFFZs: Seismicity, Fluid-Flow and Life of fractures and seismogenic faults along MTFFZs could modify earthquake cycles and/or serve as “detectors” for changes in the stress state during interseismic phases. Despite their likely global importance, the large areas where transform faults and fracture zones occur are still underexplored, as are the coupling mechanisms between seismic activity, fluid flow, and life. This manuscript provides an interdisciplinary review and synthesis of scientific progress at or related to MTFFZs and specifies approaches and strategies to deepen the understanding of processes that trigger, maintain, and control fluid flow at MTFFZs. Keywords: transform faults, fractures zones, coupling of seismicity and fluid flow, microbial life, heat flow, fluid geochemistry, seafloor observation systems, seismic precursors 950 km of displacement (e.g., Hekinian, 1982; Wolfson-Schwehr INTRODUCTION TO MARINE and Boettcher, 2019; and online compilations1;2). TRANSFORM FAULTS AND FRACTURE Fracture zones were historically viewed as tectonically inactive ZONES (MTFFZS) structures (Isacks et al., 1968). We now recognize that several of these fracture zones are seismically active (Lay, 2019), and Transform faults are one of the three basic types of plate have been generating large-scale earthquakes like the Sumatra- boundaries in plate tectonics. They are so called “conservative” Wharton Basin Earthquake in 2012 (Mb8.6; Hill et al., 2015) plate boundaries as – unlike at divergent spreading centers or along the Atlantic Azores-Gibraltar Fracture Zone in 1755 and convergent subduction/collision zones – plate material is (Great Lisbon Earthquake; Mw > 8.5; Gutscher, 2004) and in neither created nor destroyed. Kinematically, transform faults 1941 (M8.4; Lay, 2019). Oceanic transform plate boundaries may are strike-slip faults that usually link the other two types of also act as pathways for hydrothermal circulation. A well-known plate boundaries. The discovery of transform plate boundaries example where off-axis seismicity is linked to hydrothermal (Wilson, 1965) played a fundamental role in the development fluid flow is the Lost City Hydrothermal Field (Atlantis of the theory of plate tectonics as they were recognized to Massif, Central North Atlantic), where faulting in combination follow the trace of “small circles” according to the spherical with serpentinization-driven expansion of uplifted mantle Eulerian geometry (Morgan, 1968). Transform faults can be rocks provides open pathways for hydrothermal circulation oceanic or continental, depending on the type of crust they and associated water-rock interactions (Kelley et al., 2001). crosscut. On the ocean floor transform faults are in most cases Serpentinization produces high concentrations of CH4 and H2 linked to plate growth structures (e.g., Gerya, 2010, 2013a,b; in the fluids (e.g., Kelley et al., 2001) that provide energy Giustiniani et al., 2015; for exceptions see Hey et al., 1980) as they for chemosynthetic biota at the seafloor, and possibly below commonly accommodate the progressive horizontal movements (see Figure 3). Hydrothermal fluids of deep crustal origin between two adjacent mid-ocean ridges – ridge-ridge transform have also been suggested to play a role in mud volcanism faults (RRTF; Figure 1). Besides the most abundant RRTF, there (Hensen et al., 2015). are also ridge-trench (e.g., Mendocino Transform Fault) and Three decades of continuous ocean exploration have led trench-trench (e.g., Alpine Fault or the North Scotia Ridge) to the awareness that subsurface fluid-related processes (e.g., transform faults. fluid formation, fluid-rock interaction, fluid transport) are key Oceanic transform faults have a strong morphological phenomena affecting and controlling geodynamic processes, signature on the ocean floor with narrow valleys and steep because fluids affect almost every physical, chemical, mechanical, walls that can reach more than 2,000 m of relief (Figure 1) and thermal property of the seabed and upper crust (e.g., and water depths of >5000 m [Vema > 5100 m, Cannat Judd and Hovland, 2007). Yet, an integrated understanding et al., 1991; Romanche Trench > 7700 m, Bonatti et al., of how fluid-related geodynamic, geochemical, and biological 1994; see overviews by Hekinian (1982) and Wolfson-Schwehr processes interact is still missing, in particular in transform and Boettcher (2019)]. However, this characteristic morphology faults and fracture zones. The aim of this review is thus to usually continues for thousands of kilometers to “scar” the ocean present an overview
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