Download File

I GLOSSARY STRIKE SLIP DEFORMATION BASIN FORMATION AND SEDIMENTATION KEVIN T BIDDLE Exxon Production Research Company P O Box 2189 Houston Texas 77252 2189 AND NICHOLAS CHRISTIE BLICK Departmelll of Geological Sciences and Lamolll Doherty Geological Observatory of Columbia University Palisades Nell York 10964 INTRODUCTION Basin l A site of pronounced sediment accumulation 2 a relatively thick accumulation of sedimentary rock for Many of the geological terms having to do with strike a discussion of the history and usage of the word see Oen slip deformation basin formation and sedimentation are nis 1967 p 9 Bates and Jackson 1980 p 55 used in a variety of ways by different authors e g pull apart basin or they are synonymous with other words e g BubnofT curve A plot of subsidence versus time Fischer left lateral sinistral Rather than a enforcing rigorously 1974 uniform terminology in this book we decided to set down our preferred definitions in a glossary and where appro Bubnoff unit A standard measure of geologic rates such to indicate alternative usage In selecting terms for priate as subsidence rates defined as I m m y Fischer 1969 definition we have tried to steer a course between being Bates and Jackson 1980 p 84 overly encyclopedic and providing a list useful to those little familiarity with the geology of strike slip ba having Burial history curve A plot for a given location of the sins especially those described in this volume Some words cumulative thickness of sediments overlying a surface ver e cycle have additional meanings in the geological sci g sus time Philipp 1961 van Hinte 1978 ences not included here and this glossary should therefore be used in the context of strike slip basins The references Closing bend See restraining bend cited are those from which we obtained definitions or which illustrate the concept embodied by a particular term We Compaction I The reduction in bulk volume or thick have not attempted to provide original references for every ness of or the pore space within a body of sediment in term especially for those long used in the geological lit to the increasing weight of a superimposed load erature response 2 the physical process by which fine grained sediment is converted to Bates THE GLOSSARY consolidated rock modified from and Jackson 1980 p 127 Anastomosing Pertaining to a network of branching and rejoining surfaces or surface traces Commonly used to de Compression I A system of stresses that tends to shorten scribe braided fault systems or decrease the volume of a substance preferred definition modified from Bates and Jackson 1980 130 Uniaxial Antithetic fault Originally defined by H Cloos 1928 p involves one nonzero stress which 1936 to describe faults that dip in a direction opposite to compression principal is in triaxial all three the dip of the rocks displaced and that rotate fault bounded compressive compression principal stresses are nonzero Means 1976 80 It is also blocks so that the net slip on each fault is greater than it p pos sible for a stress to occur with one would be without rotation Oennis 1967 p 3 Many au compressive principal or more tensile stresses 2 A state of strain in thors no use the term to describe faults that I are subsidiary principal which material lines become shorter under stress to a major fault and have less displacement than that fault compressive 1 T commun 1985 and Nur 2 formed in the same stress regime as the major fault with Engelder personal Aydin 1985 this volume see contraction which they are associated 3 are oriented at a high angle to the fault in map view for strike faults in major slip bend See bend cross sectional view for normal faults and 4 for strike Compressional restraining slip faults have a sense of displacement opposite that of Compressional overstep See restraining overstep the major fault or for normal faults dip in the opposite direction Antithetic strike faults the R set of up compose Conjugate Riedel shear Synonymous with R Riedel or Reidel shears formed in shear I simple Fig antithetic shear Fig I See Riedel shear synthetic and antithetic faults Aulacogen A term introduced by Shatski 1946a b to describe narrow elongate sedimentary basins that extend Contraction A strain involving I a reduction in volume into cratons from either a geosyncline or a mountain belt e g thermal contraction or 2 a reduction of length e g that formed from a geosyncline for a discussion of genesis contraction fault of Norris 1958 McClay 1981 Con in terms of plate tectonics see Hoffman et aI 1974 traction has been gaining popularity as the general strain term associated with compressive stress much like the re Lamont Doherty Geological Observatory Contribution No 3913 lationship between the stress term tension and the strain Copyright @ 1985 The Society of Economic Paleontologists and Mineralogists 376 KEVIN T BIDDLE AND NICHOLAS CHRISTIE BLICK ANTITHETIC SHEAR EXTENSION FRACTURE RIEDEl R SHEAR MASTER SECONDARY FAULT SYNTHETIC SHEAR SYNTHETIC TENSION T EN ECHElON SHEAR FRACTURE FOLDS A B ideal conditions from cake FIG I The angular relations between structures that tend to form in right lateral simple shear under compiled clay the in models and from geological examples Arrangements for structures along left slip faults may be determined by viewing figure reverse image deformation B Riedel shear modified A Terminology largely from Wilcox et al 1973 superimposed on a strain ellipse for the overall terminology from Tchalenko and Ambraseys 1970 and Bartlett el al 1981 See glossary for definitions of terms term extension The word shortening as used by Hobbs et Dip slip fault A fault along which most of the displace ment modified from Bates and al 1976 p 27 may be a better choice for general use is accomplished by dip slip because it does not imply a volume change Jackson 1980 p 177 Convergent bend A bend in a strike slip fault that results Divergent bend A bend in a strike slip fault that results in overall crustal shortening in the vicinity of the bend syn in overall crustal extension in the vicinity of the bend syn onymous with restraining bend of Crowell 1974a onymous with releasing bend of Crowell 1974a Convergent overstep See restraining overstep Divergent overstep See releasing overstep Convergent transpressional strike slip or wrench fault Divergent transtensional strike slip or wrench fault A strike slip or wrench fault along which strike slip defor A strike slip or wrench fault along which strike slip defor mation is accompanied by a component of shortening trans mation is accompanied by a component of extension trans verse to the fault Wilcox et aI 1973 verse to the fault Wilcox et aI 1973 Harding et aI 1985 this volume Cycle I An interval of time during which one series of recurrent events is completed preferred definition 2 a Downlap A base discordant relation in which initially in sequence of sediment or rock units repeated in a succession clined strata terminate downdip against an initially hori for additional discussion see Bates and Jackson 1980 p zontal or inclined surface Mitchum 1977 p 206 156 Drag fold I A fold produced by movement along a fault A of Depositional sequence stratigraphic unit composed see normal drag and reverse drag In this context the term a of related relatively conformable succession genetically is somewhat misleading because folding commonly ini strata and bounded at its and base unconformities or top by tiates before faulting Hobbs et aI 1976 p 306 2 A 206 their correlative conformities Mitchum 1977 p minor fold formed in a less competent bed between more competent beds by movement of the competent beds in op to dextral is Dextral Pertaining the right e g slip right posite directions relative to one another Bates and Jackson slip 1980 p 186 Dip The acute angle between an inclined surface and the fold A fold in a sedimentary layer that conforms horizontal measured in a vertical to Drape plane perpendicular to the of structures strike passively configuration underlying Friedman et aI 1976 p 1049 A fold formed by dif ferential compaction is an example of a drape fold Dip separation Separation measured parallel to the dip of a fault modified from Crowell 1959 p 2662 Bates The of kinematics and kinetics and Jackson 1980 p 177 See separation Dynamic analysis study that relates strains to the evolution of stress fields Dip slip The component of slip measured parallel to the and dip of a fault Crowell 1959 p 2655 Bates and Jackson Echelon Step e g echelon faults of Clayton 1966 and faults 1980 p 177 See slip of Segall Pollard 1980 meaning overstepping GLOSSARY 377 En echelon I A stepped arrangement of relatively short synonymous with one usage of normal fault Suppe 1985 consistently overlapping or underlapping structural ele p 269 The term may be applied to faults of any dip ments such as faults or folds that are approximately parallel Christie Blick 1983 to each other but oblique to the linear or relatively narrow zone in which occur definition modified they preferred Extension fracture A mode I crack or one that shows from 1958 and Lowell 1979 see Campbell Harding Fig no motion in the plane of the crack Lawn and Wilshaw 2 En echelon arrangements can occur in both view map 1975 p 52 J T Engelder personal commun 1985 Ex and cross section Shelton 1984 and Nur 1985 this Aydin tension fractures form when effective stresses are tensile volume 2 arrangement of two or more Any stepped i e when pore fluid pressure exceeds lithostatic pres or structural elements such as faults with T overlapping underlapping sure Partly synonymous

Load more