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  • Nature Research  (3)
  • GSL (Geological Society of London)  (2)
  • 1
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    Fault-controlled hydration of the upper mantle during continental rifting (2016)
    Nature Research
    In:  Nature Geoscience, 9 (5). pp. 384-388.
    Details
    Publication Date: 2019-02-01
    Description: Water and carbon are transferred from the ocean to the mantle in a process that alters mantle peridotite to create serpentinite and supports diverse ecosystems1. Serpentinized mantle rocks are found beneath the sea floor at slow- to ultraslow-spreading mid-ocean ridges1 and are thought to be present at about half the world’s rifted margins2, 3. Serpentinite is also inferred to exist in the downgoing plate at subduction zones4, where it may trigger arc magmatism or hydrate the deep Earth. Water is thought to reach the mantle via active faults3, 4. Here we show that serpentinization at the rifted continental margin offshore from western Spain was probably initiated when the whole crust cooled to become brittle and deformation was focused along large normal faults. We use seismic tomography to image the three-dimensional distribution of serpentinization in the mantle and find that the local volume of serpentinite beneath thinned, brittle crust is related to the amount of displacement along each fault. This implies that sea water reaches the mantle only when the faults are active. We estimate the fluid flux along the faults and find it is comparable to that inferred for mid-ocean ridge hydrothermal systems. We conclude that brittle processes in the crust may ultimately control the global flux of sea water into the Earth.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1038/ngeo2671
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 2
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    Tectonic framework of the mud mounds, associated BSRs and submarine landslides off shore Nicaragua pacific margin (2008)
    GSL (Geological Society of London)
    In:  Journal of the Geological Society, 165 . pp. 167-176.
    Details
    Publication Date: 2019-10-17
    Description: The regional distribution of mounds, associated bottom-simulating reflectors (BSRs) and submarine landslides of the Pacific margin of Nicaragua suggests a genetic relationship between them. In the landslide-dominated parts of the margin, mud mounds occur in groups upslope behind the scarps and aligned parallel to the headwall. The morphotectonic features associated with the slides suggest that the slope failure could be triggered by slope oversteepening on the trailing flank of subducted seamounts. Geometric analysis of the faults triggering and controlling the mud mounds and associated BSRs also indicates that they were caused by collapses of the uplifted sea floor. Thus we propose a simple conceptual genetic model for the occurrences of the submarine landslides, surrounding mud mounds and associated BSRs in the area. Seamount subduction created locally higher fluid overpressure in the décollement. The uplift and fracturing of the margin wedge above the subducting seamount opened pathways for the overpressured fluid to escape, leading to the formation of numerous mud mounds on the sea floor and the BSR in the subsurface. The higher fluid supply locally reduced the shear strength of the sediments and facilitated failure of these sediments as landslides on the oversteepened slope caused by the subduction of the seamount.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1144/0016-76492007-012
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 3
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    Extreme crustal thinning in the south Porcupine Basin and the nature of the Porcupine Median High: Implications for the formation of non-volcanic rifted margins (2004)
    GSL (Geological Society of London)
    In:  Journal of the Geological Society, 161 . pp. 783-798.
    Details
    Publication Date: 2019-10-17
    Description: The southern Porcupine Basin is characterized by axial stretching factors that are greater than six and typical of rifted margins. As such, the basin can be regarded as a natural laboratory to investigate the evolution and symmetry of rifting leading towards continental separation and breakup. A bright reflection (here named P) cuts down to the west from the base of the sedimentary section, is overlain by small fault blocks and appears to represent a detachment fault. P may in part follow the top of partially serpentinized mantle: this interpretation is consistent with gravity modelling, and with numerical models of crustal embrittlement and mantle serpentinization during extension. Furthermore, P closely resembles the S reflection west of Iberia, where such serpentinites are well documented. Although overall the basin remains symmetrical, the consistent westward structural dip of the detachment implies that, at high stretching factors, extension became asymmetric. Farther south, the ‘Porcupine Median High’, appearing lens-shaped in cross-section, overlies the tilted fault blocks and is onlapped by postrift sediment. Despite no evidence for synrift magmatism, this high has previously been interpreted as a basaltic structure. However, it develops above the line of intersection of the crust–mantle boundary with the P detachment, and hence may be related to the spatial limit of serpentinization. The median high may represent a serpentinite mud volcano or diapir; we suggest that such structures produce the serpentinite breccias found within the rifted continent–ocean transition of nonvolcanic margins.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1144/0016-764903-036
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 4
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    Detachment tectonics at Mid-Atlantic Ridge 26°N (2019)
    Nature Research
    In:  Scientific Reports, 9 (Article number: 11830).
    Details
    Publication Date: 2022-01-31
    Description: Spreading processes associated with slow-spreading ridges are a complex interplay of volcanic accretion and tectonic dismemberment of the oceanic crust, resulting in an irregular seafloor morphology made up of blocks created by episodes of intense volcanic activity or tectonic deformation. These blocks undergo highly variable evolution, such as tilts or dissection by renewed tectonic extension, depending on their positions with respect to the spreading axis, core complexes, detachment or transform faults. Here, we use near-seafloor magnetic and bathymetric data and seismic profiles collected over the TAG Segment of the Mid-Atlantic Ridge to constrain the tectonic evolution of these blocks. Our study reveals that the presence and evolution of oceanic core complexes play a key role in triggering block movements. The deep subvertical detachment fault roots on the plate boundary, marked by a thermal anomaly and transient magma bodies. Thermal and magmatic variations control the structure and morphology of the seafloor above the subhorizontal detachment surface, occasionally leading to relocating the detachment.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
    Format: text
    Format: text
    DOI: 10.1038/s41598-019-47974-z
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 5
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    Megathrust reflectivity reveals the updip limit of the 2014 Iquique earthquake rupture (2022)
    Nature Research
    Details
    Publication Date: 2024-04-19
    Description: The updip limit of seismic rupture during a megathrust earthquake exerts a major control on the size of the resulting tsunami. Offshore Northern Chile, the 2014 Mw 8.1 Iquique earthquake ruptured the plate boundary between 19.5° and 21°S. Rupture terminated under the mid-continental slope and did not propagate updip to the trench. Here, we use state-of-the-art seismic reflection data to investigate the tectonic setting associated with the apparent updip arrest of rupture propagation at 15 km depth during the Iquique earthquake. We document a spatial correspondence between the rupture area and the seismic reflectivity of the plate boundary. North and updip of the rupture area, a coherent, highly reflective plate boundary indicates excess fluid pressure, which may prevent the accumulation of elastic strain. In contrast, the rupture area is characterized by the absence of plate boundary reflectivity, which suggests low fluid pressure that results in stress accumulation and thus controls the extent of earthquake rupture. Generalizing these results, seismic reflection data can provide insights into the physical state of the shallow plate boundary and help to assess the potential for future shallow rupture in the absence of direct measurements of interplate deformation from most outermost forearc slopes.
    Type: Article , PeerReviewed
    Format: text
    Format: text
    Format: text
    Format: text
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    OceanRep: Article in a Scientific Journal - peer-reviewed
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