000			02780nab a2200241 4500
005			20260520000317.0
008			260224s2014 xxu ing
041			_aInglés
245	0	0	_aCharacterization and development of subsurface fractures observed in the Marcellus Formation, Appalachian Plateau, north-central Pennsylvania
260			_a _b _cnov. 2014
270			_a15/12/2014 ; 15/12/2014
300			_a44 p. ; 2301-2345
520			_aTranscripción del resumen del autor: We report on subsurface deformation features measured from recently acquired core and image logs from the Marcellus Formation in north-central Pennsylvania, supplemented with data collected from Valley and Ridge outcrop. The subsurface data are from an area that bridges a gap in existing published data between outcrop in the Valley and Ridge province of Pennsylvania and the relatively undeformed outcrop exposed on the Appalachian Plateau of New York. We find one distinct set of vertical veins that strike orthogonal to Appalachian Plateau fold axes and an associated set of low-angle reverse faults and stylolites that strike parallel to fold axes. As the trend of the fold axes changes around the Pennsylvania salient, the trend of associated mesostructures changes to maintain kinematic compatibility with the shortening direction change along the salient. These structures are interpreted to support a single, although possibly protracted, strain event during Alleghanian deformation, as opposed to multiple events previously interpreted to occur in different regions and stratigraphic levels within the fold belt. The veins are associated with clusters of bedding-plane slip surfaces, which are found at distinct mechanical stratigraphic positions where the competence contrast between shale and stiff limestone units is greatest. We interpret this association to indicate that bed parallel-shear within detachment zones provides the sufficient driving force required to nucleate vertical veins, and the decoupling of beds accommodates extension orthogonal to the shortening direction. Although these veins are oriented orthogonal to the present-day maximum principal horizontal stress, they remain propped open by crystalline cements. Homogenization temperatures of fluid inclusions trapped in the veins, combined with one-dimensional burial and thermal history models, suggest that the pervasive vein set formed during the Late Pennsylvanian–Permian during the Alleghanian orogeny.
581			_a11
773	0		_tAAPG Bulletin _g98
942			_cARTICULO
100	1		_aWilkins, Scott _954300
100	1		_aMount, Van _954301
100	1		_aMahon, Keith _954302
100	1		_aPerry, Andrew _954303
100	1		_aKoenig, Jon _954304
999			_c188708 _d188708