Alex Copley

University of Cambridge

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James Jackson

University of Cambridge

Camilla Penney

University of Canterbury

Jean‐Philippe Avouac

California Institute of Technology

O M Weller

University of Cambridge

T. J. Craig

Centre for the Observation and Modelling of Earthquakes, Volcanoes and Tectonics

Sam Wimpenny

Centre for the Observation and Modelling of Earthquakes, Volcanoes and Tectonics

James Hollingsworth

Université Savoie Mont Blanc

Richard Walker

University of Oxford

John R. Elliott

Centre for the Observation and Modelling of Earthquakes, Volcanoes and Tectonics

Yani Najman

Lancaster University

Cooperative Institutions

University of Cambridge

Centre for the Observation and Modelling of Earthquakes, Volcanoes and Tectonics

University of Oxford

Centre National de la Recherche Scientifique

University of Leeds

Geological Survey of Iran

California Institute of Technology

Université Grenoble Alpes

Institut des Sciences de la Terre

British Geological Survey

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The 2012 August 11 Ahar earthquakes: consequences for tectonics and earthquake hazard in the Turkish–Iranian Plateau

Geophysical Journal International (2013)

Alex Copley Mohammad Faridi Manoucher Ghorashi James Hollingsworth James Jackson

We have examined the faulting in the 2012 August 11 Mw 6.4 and 6.3 Ahar (NW Iran) earthquakes using a combination of field mapping, remote-sensing observations of tectonic geomorphology, the cross-correlation of optical satellite images and the inversion of seismic waveforms. The first event was close to pure strike-slip, and the second was an oblique combination of thrust and strike-slip motion. Mapped surface ruptures indicate at least one of these events accommodated mostly right-lateral strike-slip motion on an ∼E–W striking plane. The occurrence of these earthquakes highlights the spatially distributed deformation in NW Iran, which has implications for both hazard assessment (the Ahar events killed over 300 people and injured over 3000), and also tectonic models of the region. Furthermore, these earthquakes demonstrate that the tectonics of the Ahar area is characterized by strike-slip faulting and a component of shortening, and not the previously suggested extension.

10.1093/gji/ggt379

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Citations (45)

Corrigendum to: Links between foreland rheology and the growth and evolution of a young mountain belt in New Guinea

Geophysical Journal International (2022)

Lizzie Knight Alex Copley Claudia Bertoni R. A. Sloan Richard Walker

New guinea

10.1093/gji/ggab489

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The February 2008 Methoni earthquake sequence, Greece: subduction earthquakes, afterslip and deformation in the overriding plate

AGUFM (2016)

Andrew Howell K.S. Palamartchouk Jennifer A. Jackson Philip England Alex Copley

Sequence (biology)

Remotely triggered earthquakes

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The controls on the thermal evolution of continental mountain ranges

Journal of Metamorphic Geology (2022)

Alex Copley O M Weller

Abstract This paper examines the controls on the thermal evolution of continental mountain ranges and investigates how pressure ( P ) and temperature ( T ) estimates from metamorphic rocks can be used to reconstruct the thermal histories of orogenic belts. We show that one‐dimensional models can approximate the temperature structure of most continental mountain belts, and find that the metamorphic conditions typical of such tectonic settings can most easily be achieved by thickening of the mid‐ to upper‐crust above a rigid lower crustal substrate. Homogeneous thickening of the entire lithosphere can only result in these conditions under unusual circumstances. This result implies that thickening above rigid lower crust has been the dominant mode of mountain‐building preserved in the rock record. In this situation, modest rates of vertically distributed internal radiogenic heating (1±0.5 μW/m 3 ) are able to produce typical metamorphic conditions and timescales, without the requirement for an external source of heat. In a given model, peak temperature conditions for rocks originally positioned closely in depth (e.g. 5 km apart) occur at times that can be separated by over 10 Myr, highlighting the spectrum of ages and conditions that can be produced by a single geometrically simple mountain‐building event. The direction of approach in P – T space towards the highest‐ T conditions experienced by a rock (i.e. the curvature of the P – T loop) is the most diagnostic feature that allows the thermal and tectonic history of a mountain belt to be estimated, highlighting the importance of determining prograde P – T paths. Combining estimates of the peak‐ T conditions with multiple other sources of information (e.g. the timescales of metamorphism or the initial crustal thickness) can also allow the reconstruction of the mountain range evolution under most circumstances. Many configurations of continental mountain‐building result in rocks transiently passing through regions with low average thermal gradients (e.g. 10–15°C/km), suggesting that such gradients should not be used to infer the presence of subduction. Analysis of existing P – T loops from the 3.2 Ga metamorphism in the Barberton terrane suggests that mountain‐building processes at that time and place were similar to those in present‐day mountain ranges, implying that large regions of rigid continental lithosphere were already in existence, and were underthrusting the margins of mountain ranges.

Radiogenic nuclide

Mountain formation

10.1111/jmg.12664

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The Late Eocene‐Early Miocene Unconformities of the NW Indian Intraplate Basins and Himalayan Foreland: A Record of Tectonics or Mantle Dynamics?

Tectonics (2018)

Yani Najman Stuart D. Burley Alex Copley Michael J. Kelly Kaushal Pander

Abstract A well‐developed late Eocene to Miocene unconformity, termed the base Miocene unconformity (BMU), is found throughout the intraplate basins of northwestern India and has previously been ascribed to Himalayan tectonics. This hypothesis is investigated by first describing the nature and age of the BMU in the northwest (NW) Indian intraplate basins and then reconstructing the location of the BMU relative to the Himalayan deformation front at the time it formed. We suggest that formation of the BMU in western India cannot be related to Himalayan tectonic processes associated with plate loading and flexure unless the Indian plate had an elastic thickness of >125 km, which is highly unlikely. Furthermore, the resumption of deposition post unconformity rules out inversion due to compression associated with India‐Asia convergence as a cause, as these compressive forces are still present. We note the coeval nature of the unconformity in the NW Indian plate intraplate basins and the Himalayan peripheral foreland basin. If the unconformities of the Himalayan peripheral foreland basin and the NW Indian intraplate basins were formed by a common process, uplift due to circulation in the mantle is the only possible regional‐scale mechanism. Such circulation could be the result of the intrinsically time‐dependent high‐Rayleigh number convection in the mantle, which has resulted in well‐documented unconformities elsewhere, or be the result of subducting slab break‐off beneath the Himalaya.

10.1029/2018tc005286

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The effects of mountain growth in Tibet and changes in plate geometry on the motion of the Indian plate

EGU General Assembly Conference Abstracts (2009)

Alex Copley Jean‐Philippe Avouac

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Diapirs of crystal-rich slurry explain granite emplacement temperature and duration

Scientific Reports (2023)

Alex Copley O M Weller H. F. Bain

The mechanism, temperature, and timescale of granite intrusion remain controversial, with wide-ranging implications for understanding continental growth, differentiation, rheology, and deformation dynamics. In this paper we present a method for determining intrusion emplacement temperature and timescale using the characteristics of the surrounding metamorphic aureole, and apply it to the Skiddaw granite in northern England. The estimated emplacement timescale (0.1-2 Myr) implies magma transport velocities of 1-100 mm/year. At the absent or low melt fractions relevant to our estimated emplacement temperature (580-650 [Formula: see text]C), such velocities are incompatible with pluton formation by successive injections through dykes. Instead, our results indicate the intrusion of a diapir of crystal-rich slurry, solidifying before emplacement, with a rheology governed by the solid crystals. The emplacement depth is likely to be governed by the depth-dependent rheology of the surrounding rocks, occurring close to the brittle-ductile transition. The wider implications of our results relate to (1) the appreciation that much of the chemical and textural characteristics of plutons may relate to pre-emplacement crystallisation at depth, passively transported to higher crustal levels, and (2) an explanation of the difficulty of seismically imaging active plutonism.

Plutonism

Brittleness

10.1038/s41598-023-40805-2

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Citations (1)

Subsidence and Seismicity in the Groningen Region, North-East Netherlands

EGUGA (2018)

Jonathan Smith R. S. White Jean‐Philippe Avouac Alex Copley Adriano Gualandi

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The potential record of far-field effects of the India-Asia collision: Barmer Basin, Rajasthan, India