Are transform faults thermal contraction cracks?

Turcotte, Donald L.

doi:10.1029/jb079i017p02573

Cited by 166 publications

(131 citation statements)

References 16 publications

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“…The separation of the faults (1,200 km) and offset of the putative ridge axis (Ϸ240 km) in Meridiani are comparable with what is observed along ocean ridges on Earth. This similarity is to be expected if transform faults are contraction cracks that relieve the thermal stresses in the cooling lithosphere (19).…”

Section: Plate Tectonics Hypothesismentioning

confidence: 99%

“…The magnitude of displacements along transform faults is such that they are observable on Mars from orbital altitude (recognized by an offset in the magnetic imprint) even if individual features (e.g., distinct ''magnetic stripes'') cannot be resolved. Such offsets provide the best evidence of transform faulting on Earth (19). On Earth, marine surveys allow one to map magnetic anomalies at mid-ocean ridges with a resolution of a few kilometers, well matched to the typical reversal rate of the dynamo (few reversals per million years) and typical spreading rates (few centimeters per year).…”

Section: Integration Of Major Geologic Features Within the Framework mentioning

confidence: 99%

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Tectonic implications of Mars crustal magnetism

Connerney

Acuña

Ness

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

269

195

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Mars currently has no global magnetic field of internal origin but must have had one in the past, when the crust acquired intense magnetization, presumably by cooling in the presence of an Earth-like magnetic field (thermoremanent magnetization). A new map of the magnetic field of Mars, compiled by using measurements acquired at an Ϸ400-km mapping altitude by the Mars Global Surveyor spacecraft, is presented here. The increased spatial resolution and sensitivity of this map provide new insight into the origin and evolution of the Mars crust. Variations in the crustal magnetic field appear in association with major faults, some previously identified in imagery and topography (Cerberus Rupes and Valles Marineris). Two parallel great faults are identified in Terra Meridiani by offset magnetic field contours. They appear similar to transform faults that occur in oceanic crust on Earth, and support the notion that the Mars crust formed during an early era of plate tectonics.magnetic ͉ planetary ͉ plate tectonics

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Section: Plate Tectonics Hypothesismentioning

confidence: 99%

Section: Integration Of Major Geologic Features Within the Framework mentioning

confidence: 99%

Tectonic implications of Mars crustal magnetism

Connerney

Acuña

Ness

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

269

195

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“…[Fletcher et al, 1995], and footwall volume expansion during unloading [Spencer, 1982]. With respect to tectonic configuration, at midocean ridges we expect horizontal, isochron-parallel extension rather than compression because of contraction of the cooling lithosphere [Collette, 1974;Turcotte, 1974]. However, plate motion changes can put a ridge axis discontinuity and adjacent IC crust into compression [e.g., Menard and Atwater, 1968; Tucholke and Schouten, 1988].…”

Section: Interpretation Of Megamullionsmentioning

confidence: 99%

Megamullions and mullion structure defining oceanic metamorphic core complexes on the Mid‐Atlantic Ridge

Tucholke¹,

Lin²,

Kleinrock³

1998

J. Geophys. Res.

489

539

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Abstract. In a study of geological and geophysical data from the Mid-Atlantic Ridge, we have identified 17 large, domed edifices (megamullions) that have surfaces corrugated by distinctive mullion structure and that are developed within inside-corner tectonic settings at ends of spreading segments. The edifices have elevated residual gravity anomalies, and limited sampling has recovered gabbros and serpentinites, suggesting that they expose extensive cross sections of the oceanic crust and upper mantle. Oceanic megamullions are comparable to continental metamorphic core complexes in scale and structure, and they may originate by similar processes. The megamullions are interpreted to be rotated footwall blocks of low-angle detachment faults, and they provide the best evidence to date for the common development and longevity (-1-2 m.y.) of such faults in ocean crust. Prolonged slip on a detachment fault probably occurs when a spreading segment experiences a lengthy phase of relatively amagmatic extension. During these periods it is easier to maintain slip on an existing fault at the segment end than it is to break a new fault in the strong rift-valley lithosphere; slip on the detachment fault probably is facilitated by fault weakening related to deep lithospheric changes in deformation mechanism and mantle serpentinization. At the segment center, minor, episodic magmatism may continue to weaken the axial lithosphere and thus sustain inward jumping of faults. A detachment fault will be terminated when magmatism becomes robust enough to reach the segment end, weaken the axial lithosphere, and promote inward fault jumps there. This mechanism may be generally important in controlling the longevity of normal faults at segment ends and thus in accounting for variable and intermittent development of inside-corner highs.

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“…This effect has been parameterized with an elastic blocking temperature [Turcotte, 1974[Turcotte, , 1983] in thermal stress model E depicted in Figure 18. In model E, the anomalous temperature field contains contributions from both isotherm uplift (model A) and impact heating.…”

Section: Effect Of An Elastic Blocking Temperaturementioning

confidence: 99%

The evolution of impact basins: Cooling, subsidence, and thermal stress

1985

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Potentially important contributors to the topography and tectonics of multi-ring impact basins are the thermal contraction and thermal stress that accompany the loss of heat emplaced during basin formation. Heat converted from impact kinetic energy and contributed from the uplift of isotherms during cavity collapse are important components in the energy budget of a newly-formed basin. That the subsequent cooling may have been an important factor in the tectonic evolution of the Orientale basin is suggested by the deep central depression and by a surrounding region of extensive fissuring. To test these concepts, we develop models for the anomalous temperature distribution immediately following basin formation, and we calculate the resulting elastic displacement and stress fields that then would accompany cooling of the basin region. All models predict subsidence of the basin floor and a near-surface stress field consistent with fissuring. In addition, the rates of cooling and of accumulation of thermal stress are in agreement with the inferred timing of fissure formation in Orientale. The sensitivity of the predicted displacements and stresses to the initial temperature field allows us to place bounds on the quantity and distribution of impact heat emplaced during basin formation. In order to be consistent with the observed topography and the distribution of fissures in the Orientale basin, the buried heat deposited during the basin-forming event was between 1032 and 1033 erg. It is likely that most of this heat was concentrated within a distance of 100-200 km from the point of impact.

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Are transform faults thermal contraction cracks?

Cited by 166 publications

References 16 publications

Tectonic implications of Mars crustal magnetism

Tectonic implications of Mars crustal magnetism

Megamullions and mullion structure defining oceanic metamorphic core complexes on the Mid‐Atlantic Ridge

The evolution of impact basins: Cooling, subsidence, and thermal stress

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