Orogeny and orography: The effects of erosion on the structure of mountain belts

Willett, Sean D.

doi:10.1029/1999jb900248

Cited by 864 publications

(778 citation statements)

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“…Because of the complex surface and subsurface feedback mechanisms involved in mountain evolution (e.g., Beaumont et al, 2001; Willett, 1999; Zeitler et al, 2001), accurate and complete rock cooling records are critical for understanding climate and tectonic factors contributing to orogen deformation and topography. After the Himalayas, the Central Andean plateau is the second highest in the world and separates some of the driest and wettest locations on Earth.…”

Section: Introductionmentioning

confidence: 99%

Slow Long‐Term Exhumation of the West Central Andean Plate Boundary, Chile

2018

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We present a regional analysis of new low‐temperature thermochronometer ages from the Central Andean fore arc to provide insights into the exhumation history of the western Andean margin. To derive exhumation rates over 10 million‐year timescales, 38 new apatite and zircon (U‐Th)/He ages were analyzed along six ~500‐km long near‐equal‐elevation, coast parallel, transects in the Coastal Cordillera (CC) and higher‐elevation Precordillera (PC) of the northern Chilean Andes between latitudes 18.5°S and 22.5°S. These transects were augmented with age‐elevation profiles where possible. Results are synthesized with previously published thermochronometric data, corroborating a previously observed trenchward increase in cooling ages in Peru and northern Chile. One‐dimensional thermal‐kinematic modeling of all available multichronometer equal‐elevation samples reveals mean exhumation rates of <0.2 km/Myr since ~50 Ma in the PC and ~100 Ma in the CC. Regression of pseudovertical age‐elevation transects in the CC yields comparable rates of ~0.05 to ~0.12 km/Myr between ~40 and 80 Ma. Differences between the long‐term mean 1‐D rates and shorter‐term age‐elevation‐derived rates indicate low variability in the exhumation history. Modeling results suggest similar background exhumation rates in the CC and PC; younger ages in the PC are largely a function of increased heat flow and consequently an elevated geothermal gradient near the arc. Slow exhumation rates are suggestive of semiarid conditions across the region since at least the Eocene and deformation and development of the Andean fore arc around this time.

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Section: Introductionmentioning

confidence: 99%

Slow Long‐Term Exhumation of the West Central Andean Plate Boundary, Chile

2018

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“…It also leads to the intriguing suggestion that deepwater fold and thrust belts may 674 have some similarities with their tectonic counterparts, where coupling and feedback between 675 structural evolution and surface processes has been shown to be important (e.g. Willett, 1999; 676 • We have reconstructed temporal and spatial variations in cumulative strain and strain rates for the 680 four thrusts-related folds that actively deform the modern seabed in the deep water Niger Delta. 681…”

Section: Sequence Of Thrusting 636mentioning

confidence: 99%

Growth history of fault-related folds and interaction with seabed channels in the toe-thrust region of the deep-water Niger delta

Jolly

Lonergan

Whittaker

2016

Marine and Petroleum Geology

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11The deep-water fold and thrust belt of the southern Niger Delta has prominent thrusts and folds 12 oriented perpendicular to the regional slope that formed as a result of the thin-skinned gravitational 13 collapse of the delta above overpressured shale. The thrust-related folds have grown in the last 12.8 14 Ma and many of the thrusts are still actively growing and influencing the pathways of modern 15 seabed channels. We use 3D seismic reflection data to constrain and analyze the spatial and 16 temporal variation in shortening of four thrusts and folds having seabed relief in a study area of 17 2600 km 2 size in 2200-3800 m water depth. Using these shortening measurements, we have 18 quantified the variation in strain rates through time for both fault-propagation and detachment folds 19 in the area, and we relate this to submarine channel response. The total amount of shortening on 20 the individual structures investigated ranges from 1 to 4 km, giving a time-averaged maximum 21shortening rate of between 90 10 and 350 50 m/Myr (0.1 and 0.4 mm/yr). Fold shortening varies 22 both spatially and temporally: The maximum interval shortening rate occurred between 9.5 Ma and 23 3.7 Ma, and has reduced significantly in the last 3.7 Ma. We suggest that the reduction in the 24Pliocene-Recent fold shortening rate is a response to the slow-down in extension observed in the up-25 dip extensional domain of the Niger Delta gravitational system in the same time interval. In the area 26 dominated by the fault-propagation folds, the channels are able to cross the structures, but the 27 detachment fold is a more significant barrier and has caused a channel to divert for 25 km parallel to 28 the fold axis. The two sets of structures have positive bathymetric expressions, with an associated 29 present day uphill slope of between 1.5 o and 2 o . However, the shorter uphill slopes of the fault-30 propagation folds and increased sediment blanketing allow channels to cross these structures. 31Channels that develop coevally with structural growth and that cross structures, do so in positions of 32 recent strain minima and at interval strain rates that are generally less than -0.02 Ma -1 (-1 x 10 -16 s -1 ). 33 However, the broad detachment fold has caused channel diversion at an even lower strain rate of c. 34 -0.002 Ma -1 (-7 x 10 -17 s -1 ). 35 36

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“…In case of the Puna-Altiplano Plateau, changes in precipitation that result from the construction of topography may starve moisture from the headwaters of the trunk stream, favoring internal drainage and storage of material. Consequently, the trapped mass will increase the lithostatic load, which may cause regional faults to become unfavorable to accommodate further deformation (e.g., Royden 1996;Willett 1999). Thus, contractional deformation may be forced to migrate toward lower elevations in the foreland.…”

Section: Possible Feedbacks Between Erosion and Tectonics In The Centmentioning

confidence: 99%

“…Therefore, unlike the case of the Puna Plateau in which internal drainage creates a threshold beyond which erosional mass export is prohibited, when externally-draining fold-and-thrust belts are being eroded, their deformation and geometry may change continuously as topography is being built. This creates a direct feedback between tectonic deformation and erosional processes (e.g., Beaumont et al 1992;Willett et al 1993;Willett 1999).…”

Section: Possible Feedbacks Between Erosion and Tectonics In The Centmentioning

confidence: 99%

“…Given the large gradients in climate, and coupling between deformation and erosional efficiency that have been postulated for other orogens (e.g., Koons 1989;Isacks 1992;Willett 1999;Zeitler et al 2001;Burbank 2002;Reiners et al 2003;Whipple and Meade 2004;Thiede et al 2004), it is likely that the feedbacks between erosion and deformation could be important in the development of the Andes as well (Masek et al 1994;Horton 1999;Montgomery et al 2001;Lamb and Davis 2003). First, the topographic configuration and climatic conditions imply that ongoing tectonic uplift and migration of deformation in the Andes may have had a significant impact on the distribution of precipitation, and hence erosion, in space and time.…”

Section: Introductionmentioning

confidence: 99%

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