Download or read book Exhumation Associated with Continental Strike slip Fault Systems written by Alison B. Till and published by Geological Society of America. This book was released on 2007-01-01 with total page 284 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Deformational mechanisms along active strike slip faults written by Stacey Ann Tyburski and published by . This book was released on 1992 with total page 388 pages. Available in PDF, EPUB and Kindle. Book excerpt: The northwest part of the North America-Caribbean plate boundary zone is characterized by active, left-lateral strike-slip faults that are well constrained seismically and are corroborated by on- and offshore geologic mapping. The onshore plate boundary zone comprises the Motogua and Polochic fault systems of southern Guatemala which join and continue offshore as the Swan Islands fault zone along the southern edge of the Cayman trough. At the Mid-Cayman spreading center in the central Caribbean Sea, the fault motion is transferred at a 100 km wide left-step in the fault system to the Oriente fault zone. A third system, the Walton fault zone, continues east from the Mid-Cayman Spreading center to define the Gonave microplate. Seafloor features produced by strike-slip faulting along the Swan Islands and Walton fault zones have been imaged and mapped using the SeaMARC II side-scan sonar and swath bathymetric mapping system, single-channel seismic data, multichannel seismic data and 3.5 kHz depth profiles. Structures mapped along the Swan Islands and Walton fault zones include: 1) twenty-six restraining bends and five releasing bends ranging in size from several kilometers in area to several hundred kilometers in area; 2)en echelon folds which occur only within the restraining bends; 3) straight, continuous fault segments of up to several tens of kilometers in length; 4) restraining and releasing bends forming in "paired" configurations; and 5) a fault-parallel fold belt fold and thrust belt adjacent to a major restraining bend. The features observed along the Swan Islands and Walton fault systems are compared to other features observed along other strike-slip fault systems, from which empirical models have previously been derived. Based on the features observed in these strike-slip systems, a rigid plate scenario is envisioned where the geometry of the fault and the direction of plate motion have controlled the types of deformation that have occurred. In a related study, microtectonic features in an area of Neogene extension within the northwestern Caribbean plate were investigated in order to provide insight on the nature of intraplate deformation related to the motion along the plate boundary. Microtectonic features were measured in the Sula-Yojoa rift of northwestern Honduras with the intention of inverting the data to estimate stress states responsible for the observed strains. Data inversion for the estimation of stress states could not be undertaken with the available measurements, however, the observations made can be used to support several existing models for the intraplate deformation as well as to encourage the elimination of other models.
Download or read book The Orientation and Sense of Displacement of Strike slip Faults in Continental Crust written by Robert A. MacMillan and published by . This book was released on 1975 with total page 146 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Tectonic Faults written by Mark R. Handy and published by MIT Press. This book was released on 2007 with total page 472 pages. Available in PDF, EPUB and Kindle. Book excerpt: Scientists examine tectonic faulting on all scales--from seismic fault slip to the formation of mountain ranges--and discuss its connection to a wide range of global phenomena, including long-term climate change and evolution. Tectonic faults are sites of localized motion, both at the Earth's surface and within its dynamic interior. Faulting is directly linked to a wide range of global phenomena, including long-term climate change and the evolution of hominids, the opening and closure of oceans, and the rise and fall of mountain ranges. In Tectonic Faults, scientists from a variety of disciplines explore the connections between faulting and the processes of the Earth's atmosphere, surface, and interior. They consider faults and faulting from many different vantage points--including those of surface analysts, geochemists, material scientists, and physicists--and in all scales, from seismic fault slip to moving tectonic plates. They address basic issues, including the imaging of faults from Earth's surface to the base of the lithosphere and deeper, the structure and rheology of fault rocks, and the role of fluids and melt on the physical properties of deforming rock. They suggest strategies for understanding the interaction of faulting with topography and climate, predicting fault behavior, and interpreting the impacts on the rock record and the human environment. Using an Earth Systems approach, Tectonic Faults provides a new understanding of feedback between faulting and Earth's atmospheric, surface, and interior processes, and recommends new approaches for advancing knowledge of tectonic faults as an integral part of our dynamic planet.
Download or read book Continental Transpressional and Transtensional Tectonics written by Robert E. Holdsworth and published by Geological Society of America. This book was released on 1998 with total page 376 pages. Available in PDF, EPUB and Kindle. Book excerpt: Many present-day and ancient continental deformation systems appear to have formed due to significantly oblique relative plate motions. Transpression and transtension zones are formed where the oblique motions involve components of compression and extensions, respectively. This book covers the recent advances in our understanding or transpressional and transtensional deformation zones both in theory and in real geological settings from around the world. The volume opens with an up-to-date overview of the topic that sets the scene for the more detailed papers which follow. The papers are grouped into four sections. The first, Modelling Transpression and Transtension, includes a series of papers that discuss theoretical strain models in the context of field examples and analogue experiments. The second section details the tectonic evolution of Continental Transform Zones and includes papers on the Dead Sea Transform, western USA and Chile. The third section, Oblique Divergence Zones, has papers on gravitational collapse in the Norwegian Caledonides and in SW North America, the break-up of Gondwana and a pull-apart basin in northern China. The final section on Oblique Convergence Zones, has case studies from Brazil, European Variscides, Antarctica, the Himalayas, the Sierra Nevada batholith and Italy.
Download or read book Tectonics of Strike slip Restraining and Releasing Bends written by W. D. Cunningham and published by Geological Society of London. This book was released on 2007 with total page 496 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume addresses the tectonic complexity and diversity of strike-slip restraining and releasing bends with 18 contributions divided into four thematic sections: a topical review of fault bends and their global distribution; bends, sedimentary basins and earthquake hazards; restraining bends, transpressional deformation and basement controls on development; releasing bends, transtensional deformation and fluid flow.
Download or read book Strain Localization and Exhumation of the Lower Crust written by Alice C. Newman and published by . This book was released on 2014 with total page 202 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this thesis, I present structural and kinematic data on rock fabrics, shear zones and fault zones from the Cretaceous Malaspina orthogneiss and some of its satellite plutons in central Fiordland, New Zealand. Central Fiordland exposes a large tract of granulite- to eclogite-facies lower crust that was exhumed between late Mesozoic to Cenozoic times. The deformational structures of interest were formed and preserved during the lifecycle of a Cretaceous continental arc that involved thickening to over 60 km followed by collapse and rifting. As such, they provide an excellent opportunity to study strain localization in the deep crust and the process of exhumation. Detailed structural mapping, analysis, and the construction of a 45-kilometer cross section through the Malaspina orthogneiss and adjacent plutons reveal the spatial distribution, sequence, and kinematics of crosscutting deformational structures. The earliest structures record Cretaceous magmatism, high-grade metamorphism at the granulite and eclogite facies, and ductile flow that resulted in widespread (over 1200 km2), disorganized magmatic foliations. These events were followed by regional extension that resulted in the formation of multiple, ≤0.5 km-thick ductile, upper amphibolite facies shear zones that record cooling, hydration, and horizontal flow during the Late Cretaceous. Extension continued but changed obliquity in the early to middle Tertiary and resulted in sets of strike-slip and normal brittle to semi-brittle faults forming a sinistral transtensional system. These faults are distributed across central Fiordland and crosscut and transpose the ductile shear zones and magmatic foliations. Lastly, a change in relative plate motions resulted in the inception of the Alpine fault and the development of a late Tertiary transpressional fault system that crosscuts all previous structures. The dominant factors controlling strain localization in central Fiordland changed from magma, heat, and melting, to fluid activity, plate boundary reorganization, and reactivation of inherited structures. The succession of contrasting strain localization styles in response to changing tectonic and local conditions led to the development of multiple phases of deformation. These multiple phases of deformation allowed the deep crust to be exhumed in a heterogeneous and fragmented, or 'piecemeal', way. In particular, the inability of late Cretaceous ductile shear zones to fully exhume the lower crust was compensated by the ability of early Tertiary transtensional faults to simultaneously thin and further exhume the lower crust. Investigations of strain localization patterns in central Fiordland shed light on the causes and mechanisms of crustal exhumation, a phenomenon that is integral to the lifecycle of virtually all orogenic belts.
Download or read book Timing of Extension North south Shortening and Conjugate Strike slip Faulting in the Evolution of the Chocolate Mountains Anticlinorium written by and published by . This book was released on 2010 with total page 45 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Gavilan Hills contain a complex record of how North American continental crust responded to the switch from low angle subduction to the embryonic development of the San Andreas fault system. Within this area, major detachment faults relating to exhumation of the Orocopia Schist include the Chocolate Mountains and Gatuna faults. Though published Ar-Ar thermochronology indicates that movement along the Gatuna fault occurred sometime between about 28 and 24 Ma, our field data and published geochronology shows that the hanging wall block of the Gatuna fault includes a thick (~1.2 km) highly faulted and extended section of ~23 Ma volcanic and epiclastic rocks. Though this relationship does not rule out movement between 28 and 24 Ma, it does indicate that final displacement along the Gatuna fault occurred after ~23 Ma. Following movement on the Gatuna fault, the section of ~23 Ma volcanic and epiclastic rocks, along with all older formations and structures, were folded about the Chocolate Mountains anticlinorium. Subsequent to this initial phase of fold growth, three unconformably bounded alluvial sequences of the Bear Canyon conglomerate were deposited and then successively folded about the anticlinorium as it grew episodically. During this interval of fold growth, a conjugate set of dextral and sinistral strike-slip faults and shear zones transected the ~23 Ma unit of volcanic and epiclastic rocks. Some of these faults offset the axis of the anticlinorium or associated second order folds. Because the Indian Pass fault, the western most fault in the set of dextral strike-slip faults, cuts the ~9 to ~13 Ma basalts of Black Mountain, we interpret the conjugate set of faults and shear zones to have fanned after this date, and to represent a period of pronounced north-south shortening. The Eastern California Shear Zone (ECSZ) is a broad zone of dextral strike-slip faults that transect the Mojave Desert and Death Valley regions. It has played a major role in accommodating the dextral shear between the Pacific and North American plates prior to the formation of the San Andreas fault. According to published literature faults of the ECSZ cut and displace ~20 Ma elements of an early Miocene extensional belt and transect and displace a tuff that was deposited about 13.4 ± 0.2 Ma. This history is remarkably similar to that summarized above for the Gavilan Hills. Hence, we argue that the growth of the Chocolate Mountains anticlinorium following eruption of the ~9 – 13 Ma basalts of Black Mountain reflects north-south shortening as the ECSZ extended southward to the latitude of the Gavilan Hills. In short, our work suggests that the Gavilan Hills contains a complete record of the response of continental crust to the transition from low angle subduction of the Farallon plate to the early embryonic stages of the modem San Andreas fault
Download or read book Alaska Dinosaurs written by Anthony R. Fiorillo and published by CRC Press. This book was released on 2018-01-02 with total page 360 pages. Available in PDF, EPUB and Kindle. Book excerpt: Anthony Fiorillo has been exploring the Arctic since 1998. For him, like many others, the Arctic holds the romance of uncharted territory, extreme conditions, and the inevitable epic challenges that arise. For Fiorillo, however, the Arctic also holds the secrets of the history of life on Earth, and its fossils bring him back field season after field season in pursuit of improving human understanding of ancient history. His studies of the rocks and fossils of the Arctic shed light on a world that once was, and provide insight into what might be.
Download or read book Tectonics of Sedimentary Basins written by Cathy Busby and published by John Wiley & Sons. This book was released on 2011-12-07 with total page 1034 pages. Available in PDF, EPUB and Kindle. Book excerpt: Investigating the complex interplay between tectonics and sedimentation is a key endeavor in modern earth science. Many of the world's leading researchers in this field have been brought together in this volume to provide concise overviews of the current state of the subject. The plate tectonic revolution of the 1960's provided the framework for detailed models on the structure of orogens and basins, summarized in a 1995 textbook edited by Busby and Ingersoll. Tectonics of Sedimentary Basins: Recent Advances focuses on key topics or areas where the greatest strides forward have been made, while also providing on-line access to the comprehensive 1995 book. Breakthroughs in new techniques are described in Section 1, including detrital zircon geochronology, cosmogenic nuclide dating, magnetostratigraphy, 3-D seismic, and basin modelling. Section 2 presents the new models for rift, post-rift, transtensional and strike slip basin settings. Section 3 addresses the latest ideas in convergent margin tectonics, including the sedimentary record of subduction intiation and subduction, flat-slab subduction, and arc-continent collision; it then moves inboard to forearc basins and intra-arc basins, and ends with a series of papers formed under compessional strain regimes, as well as post-orogenic intramontane basins. Section 4 examines the origin of plate interior basins, and the sedimentary record of supercontinent formation. This book is required reading for any advanced student or professional interested in sedimentology, plate tectonics, or petroleum geoscience. Additional resources for this book can be found at: www.wiley.com/go/busby/sedimentarybasins.
Download or read book Structural Control of Mineral Deposits written by Alain Chauvet and published by MDPI. This book was released on 2019-04-16 with total page 256 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Structural Control” remains a crucial point that frequently lacks in any scientific and/or economic analysis of ore deposits, whatever their type and class. The case of lode deposits is exemplary, although also other deposits, like breccia pipe, stockwerk, massive sulphides, skarn, etc., can, surprisingly, be concerned. Several concepts like the gold-bearing shear zone have not proven valid during the last few decades in terms of our understanding of gold deposit and have been totally abandoned. Additionally, the relationships between magmatism, regional tectonic context, and mineralization remain uncertain and have been debated in several recent publications. This demonstrates that this issue is still relevant, and its solution may help in the distinction between intrusion-related and orogenic deposits. In this Special Issue, we particularly invite any case study of mineral deposits, in which it has been demonstrated that structural geology may have a significant role in the establishment of the deposit model of formation and/or on exploration and exploitation programs. Examples in which the structural model diverges from those described in the classical literature are particularly welcomed, including studies in which relationships with magmatism can be suspected and/or demonstrated. Indeed, all cases that illustrate concepts that differ from the classic ones and from theoretical models may represent significant contributions to this volume.
Download or read book Coupled Interactions Between the Seismogenic Zone and the Ductile Root of Faults written by Kali L. Allison and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis focuses on understanding the interaction between the seismogenic zone of strike-slip faults and their ductile roots, and resulting implications for the structure and dynamics of the continental lithosphere in which they are embedded. A wide range of observations highlight the significance of this interaction, including the time- and depth-dependence of transient postseismic deformation (both frictional afterslip and bulk viscous flow), the triggering of aftershocks by viscous flow, the spatiotemporal distribution of microseismicity, and microstructural data from exhumed faults. Furthermore, the depth-extent of large strike-slip earthquakes appears to be limited to the mid-crust, resulting from a transition in deformation style or material properties in the middle and to lower crust. Previous work has demonstrated by increasing temperature with depth in the crust causes two significant transitions: a transition in frictional properties on the fault from velocity-weakening (VW) to velocity-strengthening (VS), and a transition in off-fault deformation from brittle deformation to crystal-plastic creep (the brittle-ductile transition, or BDT). Both of these transitions are estimated to occur roughly at 10-20~km depth, and therefore both are candidates for control over the nucleation depth of large earthquakes and their downdip propagation limit, and therefore control over an upper bound on the largest earthquake possible on a strike-slip fault. As both transitions are temperature-dependent, the effects of heat generation through frictional and viscous shear heating will impact the structure and dynamics of the system, possibly producing a shallow BDT and smaller earthquakes. This work is performed in the context of earthquake cycle simulations, in which all phases of the earthquake cycle are modeled. In the interseismic period, slow tectonic loading causes a stress concentration to build up on the fault, which spontaneously nucleates each earthquake. The propagation of the rupture up and down the fault is then simulated, and finally the postseismic period is simulated as well. These simulations allow the slip, stress drop, and recurrence interval of each earthquake to develop in a way that is self-consistent with the history of earthquakes and postseismic deformation. Previous earthquake cycle work has generally focused on either the frictional transition on the fault or the transition from brittle to ductile deformation. Simulations which take the first approach simulate rate-and-state friction on the fault, representing the off-fault material as linear elastic, and are able to explore a rich variety of event types and sizes, including large and small earthquakes and slow slip events. They are also able to reproduce a number of observations, including: the general time scale of each phase of the earthquake cycle, the depth-extent of the seismogenic zone, and the signature of frictional afterslip in surface deformation. Other work, which takes the second approach, models the off-fault material with a thermally activated creep law, but kinematically imposes the earthquakes. These studies are able to explore the structure of the shear zones beneath faults, the time-dependence of the effective viscosity, and the effects of viscous shear heating. A few recent studies have included both transitions simultaneously, and have been able to reproduce observations of elevated bulk viscous flow in the postseismic period and the existence of a region of both coseismic slip and bulk viscous flow. My work fits into this last category, and I focus on the interaction between rate-and-state friction and viscoelastic material in the lower crust and upper mantle. In this thesis, I develop a thermomechanical finite difference code which is able to simulate earthquake cycles with the fault described by rate-and-state friction and viscoelastic off-fault material represented with a nonlinear power-law rheology, including both frictional and viscous shear heating. The primary focus is on representing the BDT as a broad transition zone whose depth is not imposed a priori, but rather results from the solution of the system of governing equations. The philosophy is to start with the simplest case that combines spontaneously nucleating earthquakes with bulk viscous flow. As a result these simulations are performed in antiplane strain in two-dimensions, with a vertical strike-slip fault. I also use the quasidynamic approximation in the first two chapters, an approximation which makes the development of the numerical method simpler by neglecting wave-mediated stress transfer. In the first chapter of the thesis, I perform viscoelastic cycle simulations. I consider a range of background geotherms, and find that this produces qualitatively different deformation styles in the lower crust and upper mantle, ranging from significant fault creep at depth in the coolest model to purely bulk viscous flow in the warmest model. The simulations presented in this study encompass the range of effective viscosity estimates for the Wester US from deformation studies, indicating that the effective viscosity estimates imply a great deal of uncertainty in the predominant deformation mechanism of the lower crust. Later in the thesis, I incorporate a method for the simulation of fully dynamic ruptures in the coseismic period into the viscoelastic cycle simulation code. I also explore criteria for switching from the quasidynamic method in the interseismic period to the fully dynamic method in the coseismic period and back, based on the magnitude of the radiation damping term relative to the quasi-static shear stress. In the next part of the thesis, I extend this work to include frictional and viscous shear heating, which produces elevated temperature (or thermal anomaly relative to the background geotherm) near the fault. This reduces the effective viscosity in this region, resulting in a shallower BDT and, in some parts of parameter space, reducing the depth of earthquake nucleation and the downdip limit of coseismic slip. One significant finding of this work is that frictional and viscous shear heating both contribute roughly equally to this thermal anomaly. Part of this work was the development of a steady-state approximation to the system, in which the viscous strain rates and slip velocity are constant. I find that this steady-state approximation well-characterizes the depth of the BDT and magnitude of the cycle-average thermal anomaly.
Download or read book Belt Basin Window to Mesoproterozoic Earth written by John S. MacLean and published by Geological Society of America. This book was released on 2016-06-01 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt: With its thickness of more than 15 km of strata, covering some 200,000 km2, the Belt basin displays one of the planet's largest, best-exposed, most accessible, and best-preserved sequences of Mesoproterozoic sedimentary and igneous rocks. This volume focuses on research into this world-class province; kindles ideas about this critical era of Earth evolution; and covers aspects of the basin from its paleontology, mineralogy, sedimentology, and stratigraphy to its magmatism, ore deposits, geophysics, and structural geology.
Download or read book Tectonics of the Western Betics written by Gianluca Frasca and published by . This book was released on 2015 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The thesis focuses on the Western Betics, which is characterized by two major thrusts: 1/ the Internal/External Zone Boundary limits the internal metamorphic domain (Alboran Domain) from the fold-and-thrust belts inthe External Zone, and 2/ the Ronda Peridotites Thrust allows the juxtaposition of a hyperstretched lithosphere with large bodies of sub-continental mantle rocks on top of upper crustal rocks. First part: New structural data are presented and used to argue for two Lower Miocene E-W-trending strike-slip corridors played a major role in the deformation pattern of the Alboran Domain, in which E-W dextral strike-slip faults, N60°-trending thrusts and N140°-trending normal faults developed simultaneously during dextral strike-slip simple shear. The inferred continuous westward translation of the Alboran Domain is accommodated by a major E-W-trending lateral ramp (strike-slip) and a N60°-trending frontal thrust. At lithosphere-scale, we interpret the observed deformation pattern as the upper-plate expression of a lateral slab tear and of its westward propagation since Lower Miocene. The crustal emplacement of the Ronda Peridotites occurred at the onset of this westward motion. Second part: New structural data together with Ar-Ar ages serve to document the changes in deformation processes that accommodate the progressive necking of a continental lithosphere. We identify three main successive steps. First, a mid-crustal shear zone and a crust-mantle shear zone accommodate ductile crust thinning and ascent of the sub-continental mantle. The shear zones act synchronously but with opposite senses of shear, top-to-W and top-to-E respectively in the crust-mantle extensional shear zone, and at the brittle-ductiletransition in the crust. Second, hyper-stretching localizes in the neck, leading to an almost disappearance of the ductile crust and to crustal stretching values larger than 2000%, and bringing the upper crust into contact with the subcontinental mantle, each of them with theiralready acquired opposite senses of shear. Finally, high-angle normal faulting, dated by 40Ar-39Ar step-heating method on muscovite at ca. 21 Ma, cut through the Moho, where the ductile crust almost disappear and related block tilting ends the full exhumation of mantle in the zone of localized stretching. Third part: New geochronological data precisely constrain the transition from rifting to thrusting. Using U-Pb LA-ICP-MS dating, we identify two distinct episodes of crustal melting associated with two large-scale tectonic contacts that bound the Ronda Peridotites. The first episode of partial melting within the HT foliation at ca. 22.5 Ma is related to the extreme thinning of the continental crust and to mantle exhumation. The second episode of crustal melting at ca. 20 Ma, marked by leucocratic granite dikes, is related to the thrust emplacement of the section of thinned and hot continental lithosphere on top of crustal rocks.
Download or read book Detachment Faulting Within the Northern Channel Islands Platform written by Elizabeth Dianne Baker and published by . This book was released on 1993 with total page 344 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Ophiolites Arcs and Batholiths written by James Earl Wright and published by Geological Society of America. This book was released on 2008-01-01 with total page 582 pages. Available in PDF, EPUB and Kindle. Book excerpt: Wright (geology, U. of Georgia) and Shervais (geology, Utah State U.) edit selections from a symposium titled "Ophiolites, Batholiths, and Regional Geology: A Session in Honor of Cliff Hopson" held at the Cordilleran Section Meeting of The Geological Society of America in 2005. With contributions from geologists and earth scientists from throughout the United States, the title contains separate sections for papers on the topics of ophiolites, arcs, and batholiths. The publication is illustrated in both black-and-white and color, but contains no index.
Download or read book Whence the Mountains written by James W. Sears and published by Geological Society of America. This book was released on 2007-01-01 with total page 440 pages. Available in PDF, EPUB and Kindle. Book excerpt: The 19 original papers on the tectonic evolution of mountain systems were collected to mark the 50th anniversary of Price's description of the Canadian Cordillera. A sampling of topics turns up the driving mechanism and three-dimensional circulation of plate tectonics, the Belt-Purcell Basic as the keystone of the Rocky Mountain fold-and-thrust belt in the US and Canada, Silurian-Devonian orogenic events in the central Appalachians and the crystalline southern Appalachians, and defining the eastern boundary of the North Asian craton from structural and subsidence history studies of the Verkhoyansk fold-and-thrust belt. A fold-out sheet of color maps and diagrams is tucked into a pocket inside the back cover.
