Post on 30-Jan-2021
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Jointing in sandstones, Arches National Park, Utah - by James R. DyerAbstractTable of contentsList of tablesList of figuresChapter one: Geology of Arches National ParkAbstractIntroductionPrevious investigationsField methodsStratigraphyPennsylvanian RocksHermosa formation
Pennsylvanian and Permian rocksCutler formation
Triassic rocksMoenkopi formationChinle formation
Triassic and Jurassic rocksGlen Canyon groupWingate sandstoneKayanta formationNavajo sandstone
Jurassic rocksSan Rafael groupEntrada sandstoneDewey Bridge memberSlick Rock memberMoab member
Summerville formation
Morrison formationSalt Wash memberBrushy Basin member
Cretaceous rocksCedar Mountain formationDakota sandstoneMancos shale
Tertiary (?) rocksFormation of Salt Valley
Quaternary (?) depositsMass wasting debris
Holocene deposits
Structural geologyRegional settingStructural geology of Arches National ParkFoldsFaultsSub-salt faultsSurface faults
Collapse structureJoints and fractures
Age of deformation
Chapter Two: Superpositon of zoned jointsAbstractIntroductionPrevious workSystematic joints and zoned jointsZoned joints in Arches National ParkOrigin of joins: Shear or extensionJoint domainsData collection and presentationDomain AObservationsDiscussion
Domain BObservationsDiscussion
Dihedral angle between joint setsDomain CObservationsDiscussion
Three-dimensional geometry of jointsObservationsDiscussion
Summary of observationsConclusions
Chapter Three: Origin of zoned jointsAbstractIntroductionGrowth of extension fracturesSresses on an elliptical crackStresses around a flat crack
Origin of joint zonesDeformation at the crack tipConclusions
Chapter Four: The influence of lithology on jointingAbstractIntroductionLithologic comparisonsMoab memberSlick rock member
Velocity measurementsDiscussions
The role of anisotropyConclusions
Chapter Five: the stress field about a joint zoneAbstractIntroductionJoints as paleostress indicatorsStress field about a joint zoneResolved stresses on the crackSolving for the stress field
Boundary conditions1. Open crack2. Closed crack
Examplesi. Closed crackia. Locked jointib. Frictional slidingic. Frictionless jointP ropagation of a younger joint
ii. Open crackia. is compressiveiib. are tensile
Conclusions
Appendix AAppendix BReferences cited