The influence of mechanical properties on the link between tectonic and topographic evolution

Koons, P. O.; Upton, Phædra; Barker, A. D.

doi:10.1016/j.geomorph.2010.11.012

Cited by 60 publications

(52 citation statements)

References 81 publications

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“…Microseismic monitoring techniques have recently been used to detect and characterise a 38 range of geomorphic processes, including ocean wave energy delivery to coastal cliffs 39 Koons et al, 2012). If microseismic cyclic loading is 63 effective in weakening rocks in an incremental, preparatory manner and, hence, permitting 64 fracture to occur more readily, this may be an important yet rarely considered process in 65 driving slope failure.…”

Section: Introduction and Scope 37mentioning

confidence: 99%

Are microseismic ground displacements a significant geomorphic agent?

et al. 2014

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The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. Abstract 5 This paper considers the role that microseismic ground displacements may play in fracturing 6 rock via cyclic loading and subcritical crack growth. Using a coastal rock cliff as a case 7 study, we firstly undertake a literature review to define the spatial locations that may be prone 8 to microseismic damage. It is suggested that microseismic weakening of rock can only occur 9 in 'damage accumulation zones' of limited spatial extent. Stress concentrations resulting from 10 cliff height, slope angle and surface morphology may nucleate and propagate a sufficiently 11 dense population of microcracks that can then be exploited by microseismic cyclic loading. 12We subsequently examine a 32-day microseismic dataset obtained from a coastal cliff-top 13 location at Staithes, UK. The dataset demonstrates that microseismic ground displacements 14 display low peak amplitudes that are punctuated by periods of greater displacement during 15 storm conditions. Microseismic displacements generally display limited preferential 16 directivity, though we observe rarely occurring sustained ground motions with a cliff-normal 17 component during storm events. High magnitude displacements and infrequently experienced 18 ground motion directions may be more damaging than the more frequently occurring, 19 reduced magnitude displacements characteristic of periods of relative quiescence. As high 20 magnitude, low frequency events exceed and then increase the damage threshold, these 21 extremes may also render intervening, reduced magnitude microseismic displacements 22 ineffective in terms of damage accumulation as a result of crack tip blunting and the 23 2 generation of residual compressive stresses that close microcracks. We contend that damage 24 resulting from microseismic ground motion may be episodic, rather than being continuous 25 and in (quasi-)proportional and cumulative response to environmental forcing. A conceptual 26 model is proposed that describes when and where microseismic ground motions can operate 27 effectively. We hypothesise that there are significant spatial and temporal limitations on 28 effective microseismic damage accumulation, such that the net efficacy of microseismic 29 ground motions in preparing rock for fracture, and hence in enhancing erosion, may be 30 considerably lower than previously suggested in locations where high magnitude 31 displacements punctuate 'standard' displacement conditions. Determining and measuring the 32 exact effects of microseismic ground disp...

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Section: Introduction and Scope 37mentioning

confidence: 99%

Are microseismic ground displacements a significant geomorphic agent?

et al. 2014

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“…We integrate data and interpretations from the Southern South Island using a variety of geological and geophysical sources to constrain our models, including the stratigraphic record [13,14,16], structural observations [15,[17][18][19], observations of crustal velocity and thickness across the South Island [20][21][22][23][24][25] and previous modelling studies [6,[26][27][28]. There has been only limited bedrock erosion across this region since the Miocene so that many aspects of the paleogeography are still preserved [29].…”

Section: Introductionmentioning

confidence: 99%

Far-Field Deformation Resulting from Rheologic Differences Interacting with Tectonic Stresses: An Example from the Pacific/Australian Plate Boundary in Southern New Zealand

2014

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The Miocene in Southern New Zealand was dominated by strike-slip tectonics. Stratigraphic evidence from this time attests to two zones of subsidence in the south: (a) a middle Cenozoic pull-apart basin and (b) a regionally extensive subsiding lake complex, which developed east and distal to the developing plate boundary structure. The lake overlay a block of crust with a significantly weak mid-crustal section and we pose the question: can rheological transitions at an angle to a plate boundary produce distal subsidence and/or uplift? We use stratigraphic, structural and geophysical observations from Southern New Zealand to constrain three-dimensional numerical models for a variety of boundary conditions and rheological scenarios. We show that coincident subsidence and uplift can result from purely strike-slip boundary conditions interacting with a transition from strong to weak to strong mid-crustal rheology. The resulting pattern of vertical displacement is a function of the symmetry or asymmetry of the boundary conditions and the extent and orientation of the rheological transitions. For the Southern New Zealand case study, subsidence rates of ~0.1 mm/yr are predicted for a relative plate motion of 25 mm/yr, leading to ~500 m of subsidence over a 5 Ma time period, comparable to the thickness of preserved lacustrine sediments. OPEN ACCESSGeosciences 2014, 4 94

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“…This magnitude of damage is small; consequently, it is the spatial pattern of damage that plays a pivotal role in strain localization by concentrating surface runoff into networks of highly erodible rock across entire orogens. We expect oblique orogens to host greater strain localization due to a greater frequency of shear zone intersections (Koons et al, 2012). Strain is also sensitive to the load distribution produced by dendritic drainage patterns, but this effect is minimal because the drainage pattern, and hence the topographic stress field, does not necessarily coincide with strain-weakened zones (Figs.…”

Section: Strain-erosion Feedbackmentioning

confidence: 93%

“…Despite the establishment over the past century of the concept that feedbacks exist between tectonic and erosional processes, there has been minimal progress in exploring how mechanical heterogeneities in rock could affect interaction between tectonism and erosion (Molnar et al, 2007;Koons et al, 2012). In this paper, we make theoretical predictions about the role of heterogeneous rock strength in orogenic-scale (>100 km) drainage network evolution and the significance of surface erosion in strain localization.…”

Section: Introductionmentioning

confidence: 99%

Dynamic links among rock damage, erosion, and strain during orogenesis

Roy

Koons

Upton

et al. 2016

Geology

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We provide model evidence for a previously unexplored positive feedback between tectonic strain and fluvial erosion by considering rock erodibility as a function of shear damage. Plastic shear strain permanently damages the upper crust within planar shear zones, providing a greater ease for detachment and transport by fluvial processes. The subsequent rapid erosion of exposed shear zones reforms the topographic stress field in a way that encourages continued accommodation of strain, a positive feedback response that becomes more prominent with greater shear damage. Based on model results and natural examples, rock strength heterogeneity plays a major role in the evolution of drainage network patterns and the capability for valley-scale strain localization in active orogens.

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The influence of mechanical properties on the link between tectonic and topographic evolution

Cited by 60 publications

References 81 publications

Are microseismic ground displacements a significant geomorphic agent?

Are microseismic ground displacements a significant geomorphic agent?

Far-Field Deformation Resulting from Rheologic Differences Interacting with Tectonic Stresses: An Example from the Pacific/Australian Plate Boundary in Southern New Zealand

Dynamic links among rock damage, erosion, and strain during orogenesis

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