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The Influence of Volcanic Resurfacing on the Growth of Normal Faults in Icelandic Rifts.

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	The Influence of Volcanic Resurfacing on the Growth of Normal Faults in Icelandic Rifts./
作者:	Sheehan, Stephen D.
面頁冊數:	1 online resource (63 pages)
附註:	Source: Masters Abstracts International, Volume: 84-07.
Contained By:	Masters Abstracts International84-07.
標題:	Geology. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=29998941click for full text (PQDT)
ISBN:	9798368437354

The Influence of Volcanic Resurfacing on the Growth of Normal Faults in Icelandic Rifts.
Sheehan, Stephen D.

The Influence of Volcanic Resurfacing on the Growth of Normal Faults in Icelandic Rifts. - 1 online resource (63 pages)

Source: Masters Abstracts International, Volume: 84-07.

Thesis (M.S.)--University of Colorado at Boulder, 2022.

Includes bibliographical references

Extensional fault systems are strongly governed by the rheology, or strength of materials they deform. In the simplest case with isotropic rocks, normal faults grow upward and laterally, developing distinctive patterns of displacement along their lengths described by fault scaling. Brittle deformation is dictated by strain weakening, where greater displacement along faults decreases the frictional resistance to slip along them. As linkage of adjacent faults develops, larger faults preferentially accommodate slip in broader fault arrays, often shutting off smaller ones. For dip slip faults that are continuously buried as they grow upward, shear is often discretized across an upwardly widening zone, described as a trishear envelope. For an active tectonic landscape, burial resets the pattern of strain visible at the surface, as faults break upward through new deposits with ongoing extension. An ideal laboratory for study of extensional faults continually covered by thick volcanic deposits includes Iceland, where high strain rates, little post glacial erosion and excellent datasets of surface topography allow detailed patterns of surface fault rupture and folding to be considered. 173 fault scarp displacement to length (D:L) profiles were measured in three Icelandic rift zones to examine the mechanisms of extensional fault growth in areas resurfaced by Holocene basalt flows. Segmentation, commonly observed in D:L profiles, provides insight into the prior lateral propagation and linkage histories of faults, while the geometry of surficial monoclines aids in constraining the kinematics of vertical growth for varied cover thickness. Longer faults displayed greater segmentation along strike and were more common in faster spreading rifts, whereas rifts forming at lower rates contained shorter fault segments formed by fewer linkages of older, shorter segments. Measurements of faults covered by variable thicknesses of younger basalt flows suggest that folding at the surface, as defined by trishear kinematics is favored in examples with thicker cover. The character of thick basalt flows in Iceland, in particular the common occurrence of columnar jointing drives a unique type of upward fault propagation, where spectacular fissures associated with bending at the footwall margin of the trishear envelope act as strain guides for subsequent surface fault rupture and scarp development. This focusing continuously pins shear to the footwall margin of the trishear strain envelope and is consistent with mechanical modeling of comparable examples with boundary conditions similar to rifts on Iceland.

Electronic reproduction.
Ann Arbor, Mich. :
ProQuest,
2023

Mode of access: World Wide Web

ISBN: 9798368437354Subjects--Topical Terms:

516570
Geology.
Subjects--Index Terms:

Extensional fault systemsIndex Terms--Genre/Form:

542853
Electronic books.

The Influence of Volcanic Resurfacing on the Growth of Normal Faults in Icelandic Rifts.
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520 $a Extensional fault systems are strongly governed by the rheology, or strength of materials they deform. In the simplest case with isotropic rocks, normal faults grow upward and laterally, developing distinctive patterns of displacement along their lengths described by fault scaling. Brittle deformation is dictated by strain weakening, where greater displacement along faults decreases the frictional resistance to slip along them. As linkage of adjacent faults develops, larger faults preferentially accommodate slip in broader fault arrays, often shutting off smaller ones. For dip slip faults that are continuously buried as they grow upward, shear is often discretized across an upwardly widening zone, described as a trishear envelope. For an active tectonic landscape, burial resets the pattern of strain visible at the surface, as faults break upward through new deposits with ongoing extension. An ideal laboratory for study of extensional faults continually covered by thick volcanic deposits includes Iceland, where high strain rates, little post glacial erosion and excellent datasets of surface topography allow detailed patterns of surface fault rupture and folding to be considered. 173 fault scarp displacement to length (D:L) profiles were measured in three Icelandic rift zones to examine the mechanisms of extensional fault growth in areas resurfaced by Holocene basalt flows. Segmentation, commonly observed in D:L profiles, provides insight into the prior lateral propagation and linkage histories of faults, while the geometry of surficial monoclines aids in constraining the kinematics of vertical growth for varied cover thickness. Longer faults displayed greater segmentation along strike and were more common in faster spreading rifts, whereas rifts forming at lower rates contained shorter fault segments formed by fewer linkages of older, shorter segments. Measurements of faults covered by variable thicknesses of younger basalt flows suggest that folding at the surface, as defined by trishear kinematics is favored in examples with thicker cover. The character of thick basalt flows in Iceland, in particular the common occurrence of columnar jointing drives a unique type of upward fault propagation, where spectacular fissures associated with bending at the footwall margin of the trishear envelope act as strain guides for subsequent surface fault rupture and scarp development. This focusing continuously pins shear to the footwall margin of the trishear strain envelope and is consistent with mechanical modeling of comparable examples with boundary conditions similar to rifts on Iceland.
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