scholarly journals IODP workshop: Core-Log Seismic Investigation at Sea – Integrating legacy data to address outstanding research questions in the Nankai Trough Seismogenic Zone Experiment

2018 ◽  
Vol 24 ◽  
pp. 93-107
Author(s):  
Anna Cerchiari ◽  
Rina Fukuchi ◽  
Baiyuan Gao ◽  
Kan-Hsi Hsiung ◽  
Dominik Jaeger ◽  
...  
Keyword(s):  
Subduction Zone ◽  
Seismic Data ◽  
Subduction Zones ◽  
Nankai Trough ◽  
Early Career ◽  
Seismogenic Zone ◽  
Geochemical Data ◽  
Deformation Front ◽  
Subduction Zone Processes ◽  
Research Questions

Abstract. The first International Ocean Discovery Program (IODP) Core-Log-Seismic Integration at Sea (CLSI@Sea) workshop, held in January–February 2018, brought together an international, multidisciplinary team of 14 early-career scientists and a group of scientific mentors specialized in subduction zone processes at the Nankai Trough, one of the Earth's most active plate-subduction zones located off the southwestern coast of Japan. The goal of the workshop was to leverage existing core, log, and seismic data previously acquired during the IODP's Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE), to address the role of the deformation front of the Nankai accretionary prism in tsunamigenic earthquakes and slow slip in the shallow portion of the subduction interface. The CLSI@Sea workshop was organized onboard the D/V Chikyu concurrently with IODP Expedition 380, allowing workshop participants to interact with expedition scientists installing a long-term borehole monitoring system (LTBMS) at a site where the workshop's research was focused. Sedimentary cores from across the deformation front were brought onboard Chikyu, where they were made available for new description, sampling, and analysis. Logging data, drilling parameters, and seismic data were also available for investigation by workshop participants, who were granted access to Chikyu laboratory facilities and software to perform analyses at sea. Multi-thematic presentations facilitated knowledge transfer between the participants across field areas, and highlighted the value of multi-disciplinary collaboration that integrates processes across different spatiotemporal scales. The workshop resulted in the synthesis of existing geophysical, geologic, and geochemical data spanning IODP Sites C0006, C0007, C0011 and C0012 in the NanTroSEIZE area, the identification of key outstanding research questions in the field of shallow subduction zone seismogenesis, and fostered collaborative and individual research plans integrating new data analysis techniques and multidisciplinary approaches.

Rapid, paced metamorphism of blueschists from laser-based Lu-Hf garnet-domain geochronology and LA-ICMPS trace element mapping

2021 ◽  
Author(s):  
Lorraine Tual ◽  
Matthijs Smit ◽  
Jamie Cutts ◽  
Ellen Kooijman ◽  
Melanie Kielman-Schmitt ◽  
...  
Keyword(s):  
Trace Element ◽  
Subduction Zone ◽  
Subduction Zones ◽  
Micro Milling ◽  
Individual Growth ◽  
Garnet Growth ◽  
Subduction Zone Processes ◽  
Growth Zones ◽  
Fluid Release ◽  
Element Mapping

<p>Unravelling the timing and rate of subduction-zone metamorphism requires linking the composition of petrogenetic indicator minerals in blueschists and eclogites to time. Garnet is a key mineral in this regard, not in the least because it best records P-T conditions and changes therein and can be dated, using either Lu-Hf or Sm-Nd chronology. Bulk-grain garnet ages are the norm and can provide important and precise time constraints on reactions across both facies. Domain dating, i.e., dating of individual growth zones, moves beyond that. Domain dating by combining mechanical micro-milling and Sm-Nd chronology yielded important constraints on garnet-growth and fluid-release rates for blueschists (e.g., Dragovic et al., 2015). Developing this method for Lu-Hf chronology and, importantly, for "common-sized" garnet (≤1 cm) provides an important opportunity to further explore the potential of this approach.</p><p>We combined a low-loss micro-sampling technique in laser cutting with a refined Lu-Hf routine to precisely date multiple growth zones of a sub-cm-sized garnet in a blueschist. The targeted grain from a glaucophane-bearing micaschist from Syros Island, Greece, was chemically characterized by major- and trace-element mapping (EPMA, LA-ICPMS) and five zones were extracted using a laser mill. The three core and inner mantle zones are chemically comparable and identical in age within a 0.1 Myr precision (2σ). The outer two zones are chemically distinct and are resolvably younger (0.2-0.8 Myr). The timing of these two major garnet-growth episodes, together with the variations in trace-element chemistry, constrain important fluid-release reactions, such as chloritoid-breakdown. The data show that the integral history of garnet growth in subduction zones may be extremely short (<1 Myr), but may, even in that short timeframe, consist of multiple short pulses. Garnet-forming reactions clearly are localized and, thus, associated with focussed high-flux fluid flow. Beyond subduction-zone processes, our new protocol for zoned garnet Lu-Hf geochronology of "common-sized" garnet opens possibilities for constraining the causes and rates of garnet growth and in turn, the pace of tectonic processes in general.</p><p> </p><p><sub><em>Dragovic, B., Baxter, E.F. and Caddick, M.J., 2015. Pulsed dehydration and garnet growth during subduction revealed by zoned garnet geochronology and thermodynamic modeling, Sifnos, Greece. Earth and Planetary Science Letters, 413, pp.111-122.</em></sub></p>

scholarly journals IODP Expedition 334: An Investigation of the Sedimentary Record, Fluid Flow and State of Stress on Top of the Seismogenic Zone of an Erosive Subduction Margin

2013 ◽  
Vol 15 ◽  
pp. 23-30 ◽  
Author(s):  
P. Vannucchi ◽  
K. Ujiie ◽  
N. Stroncik ◽  
Keyword(s):  
Costa Rica ◽  
Subduction Zones ◽  
Accumulation Rate ◽  
Marked Change ◽  
Seismogenic Zone ◽  
Geochemical Data ◽  
Cocos Plate ◽  
Middle Slope ◽  
Upper Slope

The Costa Rica Seismogenesis Project (CRISP) is an experiment to understand the processes that control nucleation and seismic rupture of large earthquakes at erosional subduction zones. Integrated Ocean Drililng Program (IODP) Expedition 334 by R/V <i>JOIDES Resolution</i> is the first step toward deep drilling through the aseismic and seismic plate boundary at the Costa Rica subduction zone offshore the Osa Peninsula where the Cocos Ridge is subducting beneath the Caribbean plate. Drilling operations included logging while drilling (LWD) at two slope sites (Sites U1378 and U1379) and coring at three slope sites (Sites U1378–1380) and at one site on the Cocos plate (Site U1381). For the first time the lithology, stratigraphy, and age of the slope and incoming sediments as well as the petrology of the subducting Cocos Ridge have been characterized at this margin. The slope sites recorded a high sediment accumulation rate of 160–1035m m y<sup>&minus;1</sup> possibly caused by on-land uplift triggered by the subduction of the Cocos Ridge. The geochemical data as well as the <i>in situ</i> temperature data obtained at the slope sites suggest that fluids are transported from greater depths. The geochemical profiles at Site U1381 reflect diffusional communication of a fluid with seawater-like chemistry and the igneous basement of the Cocos plate (Solomon et al., 2011; Vannucchi et al., 2012a). The present-day <i>in situ</i> stress orientation determined by borehole breakouts at Site U1378 in the middle slope and Site U1379 in the upper slope shows a marked change in stress state within ~12 km along the CRISP transect; that may correspond to a change from compression (middle slope) to extension (upper slope). <br><br> doi:<a href="http://dx.doi.org/10.2204/iodp.sd.15.03.2013" target="_blank">10.2204/iodp.sd.15.03.2013</a>

scholarly journals Modeling Fluid Migration in Subduction Zones

Eos ◽  
2020 ◽  
Vol 101 ◽  
Author(s):  
Ikuko Wada ◽  
Leif Karlstrom
Keyword(s):  
Subduction Zone ◽  
Subduction Zones ◽  
Fluid Migration ◽  
Subduction Zone Processes ◽  
Working Together

Scientists from different disciplines are working together to identify common challenges in and techniques for modeling fluid migration associated with subduction zone processes.

Scientific Drilling Program of Drilling Vessel Chikyu and Drilling Data Acquisition for Future Technical Development

2011 ◽  
Author(s):  
Tomoya Inoue ◽  
Kazuyasu Wada ◽  
Eigo Miyazaki ◽  
Tsuyoshi Miyazaki
Keyword(s):  
Data Acquisition ◽  
Subduction Zones ◽  
Large Scale ◽  
Nankai Trough ◽  
Technical Development ◽  
Seismogenic Zone ◽  
Validity Data ◽  
Scientific Drilling ◽  
Drilling Data ◽  
Drilling Operations

The scientific drilling vessel Chikyu has started drilling at Nankai trough under the international organization, IODP. The Nankai trough located beneath the ocean off the southwest coast of Japan is one of the most active earthquake zones on the planet and one of the best-studied subduction zones as well. The Nankai Trough Seismogenic Zone Experiment attempts for the first time to drill, sample, and instrument the earthquake-causing or the seismogenic portion of Earth’s crust, where violent, large-scale earthquakes have occurred repeatedly throughout history. Before starting the international drilling operations, an integration drilling test off Shimokita Peninsula was conducted and we acquired actual drilling data such as vessel heave, hook load, and compensator position. Confirming its validity, data acquisition systems have worked continuously in international drilling operations. It is very important to consider the actual drilling data for the drilling operation and for further technical development. This paper describes the scientific drilling programs of the drilling vessel Chikyu and the drilling data acquisition for future technical development in relation with the sample data acquired in the internal drilling operations.

scholarly journals A new perspective of the subduction zone derived from the Ocean Drilling Program for the Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE)

2018 ◽  
Vol 124 (1) ◽  
pp. 47-65
Author(s):  
Gaku Kimura ◽  
Masataka Kinoshita ◽  
Kyuichi Kanagawa ◽  
Toshiya Kanamatsu ◽  
Jyuichiro Ashi ◽  
...  
Keyword(s):  
Subduction Zone ◽  
Nankai Trough ◽  
Seismogenic Zone ◽  
Ocean Drilling Program ◽  
Ocean Drilling ◽  
New Perspective

scholarly journals Along‐Arc Heterogeneity in Local Seismicity across the Lesser Antilles Subduction Zone from a Dense Ocean‐Bottom Seismometer Network

2019 ◽  
Vol 91 (1) ◽  
pp. 237-247 ◽  
Author(s):  
Lidong Bie ◽  
Andreas Rietbrock ◽  
Stephen Hicks ◽  
Robert Allen ◽  
Jon Blundy ◽  
...  
Keyword(s):  
Subduction Zone ◽  
Subduction Zones ◽  
Lesser Antilles ◽  
Seismogenic Zone ◽  
Ocean Bottom ◽  
Ocean Bottom Seismometer ◽  
Plate Interface ◽  
Local Seismicity ◽  
Slow Spreading ◽  
Lesser Antilles Arc

Abstract The Lesser Antilles arc is only one of two subduction zones where slow‐spreading Atlantic lithosphere is consumed. Slow‐spreading may result in the Atlantic lithosphere being more pervasively and heterogeneously hydrated than fast‐spreading Pacific lithosphere, thus affecting the flux of fluids into the deep mantle. Understanding the distribution of seismicity can help unravel the effect of fluids on geodynamic and seismogenic processes. However, a detailed view of local seismicity across the whole Lesser Antilles subduction zone is lacking. Using a temporary ocean‐bottom seismic network we invert for hypocenters and 1D velocity model. A systematic search yields a 27 km thick crust, reflecting average arc and back‐arc structures. We find abundant intraslab seismicity beneath Martinique and Dominica, which may relate to the subducted Marathon and/or Mercurius Fracture Zones. Pervasive seismicity in the cold mantle wedge corner and thrust seismicity deep on the subducting plate interface suggest an unusually wide megathrust seismogenic zone reaching ∼65  km depth. Our results provide an excellent framework for future understanding of regional seismic hazard in eastern Caribbean and the volatile cycling beneath the Lesser Antilles arc.

A Significant Increase in Interplate Seismicity near Major Historical Earthquakes Offshore Martinique (FWI)

2021 ◽  
Author(s):  
Jordane Corbeau ◽  
O’Leary Gonzalez ◽  
Nathalie Feuillet ◽  
Anne-Marie Lejeune ◽  
Fabrice R. Fontaine ◽  
...  
Keyword(s):  
Subduction Zone ◽  
Subduction Zones ◽  
Plate Boundary ◽  
Historical Earthquakes ◽  
Seismogenic Zone ◽  
Plate Interface ◽  
Seismicity Rate ◽  
Rupture Area ◽  
Interplate Seismicity ◽  
Statistical Studies

ABSTRACT Understanding the processes that may be at the origin of major earthquakes in subduction zones is highly challenging, especially in the case of slowly converging areas such as the Lesser Antilles subduction zone. Our study reveals a recorded increase in seismicity rate and cumulative seismic moment over the last two decades offshore Martinique island and, particularly, in the presumed rupture area of the major historical 1839 earthquake. This sustained seismicity is shared between extensive intermediate depth activity since the 2007 Mw 7.4 earthquake that occurred about 20 km north of Martinique and a compressive seismic cluster located in the seismogenic zone of the subduction zone. We also observe a downward migration of the seismicity along the plate interface up to a 60–65 km depth and a recorded increase in the magnitudes of the earthquakes. All these observations may indicate ongoing changes along the plate boundary interface near the area of the historical major rupture of 1839, although more detailed statistical studies and additional data are necessary to confirm this trend.

scholarly journals Cascadia megathrust earthquake rupture model constrained by geodetic fault locking

2021 ◽  
Vol 379 (2196) ◽  
pp. 20200135 ◽  
Author(s):  
Duo Li ◽  
Yajing Liu
Keyword(s):  
Subduction Zone ◽  
Subduction Zones ◽  
Seismogenic Zone ◽  
Cascadia Subduction Zone ◽  
Earthquake Rupture ◽  
Megathrust Earthquake ◽  
Fracture Dynamics ◽  
Coastal Marine ◽  
Rate And State Friction ◽  
Fault Locking

Paleo-earthquakes along the Cascadia subduction zone inferred from offshore sediments and Japan coastal tsunami deposits approximated to M9+ and ruptured the entire margin. However, due to the lack of modern megathrust earthquake records and general quiescence of subduction fault seismicity, the potential megathrust rupture scenario and influence of downdip limit of the seismogenic zone are still obscure. In this study, we present a numerical simulation of Cascadia subduction zone earthquake sequences in the laboratory-derived rate-and-state friction framework to investigate the potential influence of the geodetic fault locking on the megathrust sequences. We consider the rate-state friction stability parameter constrained by geodetic fault locking models derived from decadal GPS records, tidal gauge and levelling-derived uplift rate data along the Cascadia margin. We incorporate historical coseismic subsidence inferred from coastal marine sediments to validate our coseismic rupture scenarios. Earthquake rupture pattern is strongly controlled by the downdip width of the seismogenic, velocity-weakening zone and by the earthquake nucleation zone size. In our model, along-strike heterogeneous characteristic slip distance is required to generate margin-wide ruptures that result in reasonable agreement between the synthetic and observed coastal subsidence for the AD 1700 Cascadia Mw∼9.0 megathrust rupture. Our results suggest the geodetically inferred fault locking model can provide a useful constraint on earthquake rupture scenarios in subduction zones. This article is part of the theme issue ‘Fracture dynamics of solid materials: from particles to the globe’.

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