Abstract
Marine transform faults and associated fracture zones (MTFFZs) cover vast stretches of the ocean floor, where they play a key role in plate tectonics, accommodating the lateral movement of tectonic plates and allowing connections between ridges and trenches. Together with the continental counterparts of MTFFZs, these structures also pose a risk to human societies as they can generate high magnitude earthquakes and trigger tsunamis. Historical examples are the Sumatra-Wharton Basin Earthquake in 2012 (M8.6) and the Atlantic Gloria Fault Earthquake in 1941 (M8.4). Earthquakes at MTFFZs furthermore open and sustain pathways for fluid flow triggering reactions with the host rocks that may permanently change the rheological properties of the oceanic lithosphere. In fact, they may act as conduits mediating vertical fluid flow and leading to elemental exchanges between Earth’s mantle and overlying sediments. Chemicals transported upward in MTFFZs include energy substrates, such as H2 and volatile hydrocarbons, which then sustain chemosynthetic, microbial ecosystems at and below the seafloor. Moreover, up- or downwelling of fluids within the complex system 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.
Highlights
TO MARINE TRANSFORM FAULTS AND FRACTURE ZONES (MTFFZS)Transform faults are one of the three basic types of plate boundaries in plate tectonics
On the ocean floor transform faults are in most cases linked to plate growth structures (e.g., Gerya, 2010, 2013a,b; Giustiniani et al, 2015; for exceptions see Hey et al, 1980) as they commonly accommodate the progressive horizontal movements between two adjacent mid-ocean ridges – ridge-ridge transform faults (RRTF; Figure 1)
Based on the general information provided so far, this section is dedicated to a more detailed, exemplary description of two different types of Marine transform faults and associated fracture zones (MTFFZs), located at the southern European plate margin. These two prominent transform systems are the oceanic Azores-Gibraltar Fracture Zone, which includes the Gloria Fault and the SWIM Fault Zone, forming large parts of the in the central eastern Atlantic, and the submerged, continental NAF running through the Sea of Marmara and the northern Aegean Sea (Figure 4)
Summary
TO MARINE TRANSFORM FAULTS AND FRACTURE ZONES (MTFFZS)Transform faults are one of the three basic types of plate boundaries in plate tectonics. 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.
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