Virtually the entire Late Triassic and earliest Jurassic age section of the early Meso-zoic Newar... more Virtually the entire Late Triassic and earliest Jurassic age section of the early Meso-zoic Newark continental rift basin has been recovered in over 6770 m of continuous core as part of the Newark Basin Coring Project (NBCP). Core was collected using an offset drilling method at seven sites in the central part of the basin. The cores span most of the fluvial Stockton Formation, all of the lacustrine Lockatong and Passaic formations , the Orange Mountain Basalt, and nearly all of the lacustrine Feltville Formation. The cores allow for the first time the full Triassic-age part of the Newark basin stratigraphic sequence to be described in detail. This includes the gray, purple, and red, mostly fluvial Stockton Formation as well as the 53 members that make up the lacustrine Lockatong (mostly gray and black) and Passaic (mostly red) formations. The nearly 25% overlap zones between each of the stratigraphically adjacent cores are used to test lateral correlations in detail, scale the cores to one another, and combine them in a 4660-m-thick composite section. This composite shows that the entire post-Stockton sedimentary section consists of a hierarchy of sedimentary cycles, thought to be of Milankovitch climate cycle origin. Lithostratigraphic and magnetostrati-graphic correlations between core overlap zones and outcrops demonstrate that the individual sedimentary cycles can be traced essentially basinwide. The agreement between the cyclostratigraphy and magne-tostratigraphy shows both the cycles and the polarity boundaries to be isochronous horizons. Detailed analysis of the Newark basin shows that high-resolution cyclos-tratigraphy is possible in lacustrine, primarily red-bed rift sequences and provides a fine-scale framework for global correlations and an understanding of continental tropical climate change. This paper is dedicated to the late Alfred Froelich.
The Argana rift basin of Morocco and the Fundy rift basin of the Maritime Provinces of Eastern Ca... more The Argana rift basin of Morocco and the Fundy rift basin of the Maritime Provinces of Eastern Canada are on the conjugate margins of the central Atlantic Ocean. In the Late Triassic and Early Jurassic these basins lie at similar paleolatitudes within the same great rift system. A comparison of the depositional-and tectono-stratigraphy reveal strong similarities, much greater that those shared between the Fundy basin and other rifts in eastern North America. Both the Argana and Fundy basins are comprised of four, mostly unconformity-bound, tectonostratigraphic sequences (TS I-IV) probably controlled by pulses of extension: TS I, is Permian in age and the depositional facies of the Argana basin looks more humid than the age equivalent in the Fundy basin and the latter may not be a rift sequence; TS II, is early Late Triassic (Carnian) in age and is the most humid looking facies in both basins; TS Ill, is late Late Triassic (Norian and Rhaetian) in age and is much more arid in both basins with abundant aeolianites and evaporites; TS IV, is latest Triassic and earliest Jurassic (late Rhaetian-early Hettangian) and shows an increase in the range of variability in climate-sensitive facies-its basal part contains the Triassic-Jurassic boundary an overlying basalt flow sequence and additional fluvial and lacustrine strata on top. The dramatic similarity in both facies and sequence stratigraphy between the Argana and Fundy basins, at least during the Triassic, argues for similar tectonic control, restricted to that latitudinal swath of Pangea, as well as similar paleoclimate.
The Argana rift basin of Morocco and the Fundy rift basin of the Maritime Provinces of Eastern Ca... more The Argana rift basin of Morocco and the Fundy rift basin of the Maritime Provinces of Eastern Canada are on the conjugate margins of the central Atlantic Ocean. In the Late Triassic and Early Jurassic these basins lie at similar paleolatitudes within the same great rift system. A comparison of the depositional-and tectono-stratigraphy reveal strong similarities, much greater that those shared between the Fundy basin and other rifts in eastern North America. Both the Argana and Fundy basins are comprised of four, mostly unconformity-bound, tectonostratigraphic sequences (TS I-IV) probably controlled by pulses of extension: TS I, is Permian in age and the depositional facies of the Argana basin looks more humid than the age equivalent in the Fundy basin and the latter may not be a rift sequence; TS II, is early Late Triassic (Carnian) in age and is the most humid looking facies in both basins; TS Ill, is late Late Triassic (Norian and Rhaetian) in age and is much more arid in both basins with abundant aeolianites and evaporites; TS IV, is latest Triassic and earliest Jurassic (late Rhaetian-early Hettangian) and shows an increase in the range of variability in climate-sensitive facies-its basal part contains the Triassic-Jurassic boundary an overlying basalt flow sequence and additional fluvial and lacustrine strata on top. The dramatic similarity in both facies and sequence stratigraphy between the Argana and Fundy basins, at least during the Triassic, argues for similar tectonic control, restricted to that latitudinal swath of Pangea, as well as similar paleoclimate.
The Orpheus basin of offshore eastern Canada formed before opening of the North Atlantic Ocean. W... more The Orpheus basin of offshore eastern Canada formed before opening of the North Atlantic Ocean. We have identified four distinct tectonostratigraphic packages (A-D) associated with the basin's early development. Packages A, B, C, and D represent Paleozoic prerift strata and basement, Middle Triassic to Early Jurassic synrift strata, Early to Middle Jurassic postrift strata, and Middle to Late Jurassic postrift strata, respectively. The middle part of package B is likely salt. Rifting began by the Late Triassic and continued into the Early Jurassic. Regional shortening occurred after rifting (during the Early to Middle Jurassic), producing salt-cored detachment folds, detached thrust faults, and regional uplift and erosion. Tectonic quiescence followed shortening, leading to widespread deposition. Postrift salt movement resumed during the Middle to Late Jurassic.
Mesozoic rift basins in eastern North America formed during continental extension associated with... more Mesozoic rift basins in eastern North America formed during continental extension associated with the separation of North America and Africa. These basins locally overprint the Appalachian orogen and involve the extensional reactivation of Paleozoic faults. Half graben are thought to have formed where Mesozoic extension was subperpendicular to orogenic strike. Transtensional basins formed where the extension was more oblique. Segmented border fault systems and predominanfiy synthetic intrabasinal faults characterize the half graben. These basins resemble elongate synclines in longitudinal section; this geometry resulted from border-fault displacement that was greatest near the center of the fault and decreased toward both ends. Large-scale segmentation of some border fault systems resulted in the formation of multiple synclinal subbasins separated by transverse anticlines at segment boundaries, where fault displacement was less. As displacement increased on individual fault segments, the faults and associated basins grew in length, perhaps linking originally isolated basins. Smaller-scale fault segmentation resulted in the formation of relay ramps, rider blocks, and transverse folds. Some transverse synclines are located near the centers of fault segments, and related anticlines are located at segment boundaries. Adjacent half graben units within larger rift zones do not alternate polarity along strike and are generally not linked via accommodation zones, as in the East African rift system. Strike-slip-dominated basins are characterized by a network of strike-slip and normal faults, and are shallower and narrower than dip-slip-dominated basins. INTRODUCTION Fault-bounded sedimentary basins, typically half graben, are a fundamental manifestation of continental extension [e.g., Bally, 1982; Wernicke and Burchfiel, 1982; Anderson et al., 1983; Jackson and McKenzie, 1983; Gibbs, 1984; Rosendahl, 1987] and are also the prevalent architecture of transtensional regimes, at least within the Tanganyika-Rukwa-Malawi system in East Africa [Rosendahl et al., 1992; Scott et al., 1992]. Numerous basins formed along the margins of the incipient North Atlantic Ocean during the Mesozoic breakup of Pangea (Figure la) [Van Houten, 1977; Froelich and Olsen, 1984; Tankard and Balkwill, 1989]. In eastern North America, basins crop out over a distance of > 1700 km; other basins are concealed beneath coastal plain deposits and the continental shelf (Figure lb) (see recent summaries by Froelich and Robinson [ [ 1988]. The exposed basins are filled with thousands of meters of exclusively nonmarine strata [e.g., Smoot, 1985; Manspeizer et al., 1989; Olsen et al., 1989; Smoot, 1991] as well as tholeiitic lava flows and diabase intrusions [e.g., Froelich and Gottfried, 1988; Puffer and Philpotts, 1988; Manspeizer et al., 1989; Puffer and Ragland, 1992], most of which crystallized at-200 Ma [Sutter, 1988; Dunning and Hodych, 1990]. Biostratigraphic dating indicates that preserved basin strata range in age from Middle Triassic to Early Jurassic (Table 1) [Comet and Olsen, 1985; Olsen et al., 1989]. Rift basins in eastern North America locally overprint the Appalachian orogen and exhibit parallelism with Paleozoic contractional structures (Figure lb) [e.g., Lindholm, 1978; Swanson, 1986; Ratcliffe et al., 1986]. The exposed rift basins are situated landward of the hinge zone of the continental margin; this region experienced considerably less crustal thinning than did the seaward region [Klitgord et al., 1988]. Consequently, many of these landward basins were not deeply buried by postrift strata and therefore remain accessible today. This paper examines the similarities and differences in the architecture of exposed Mesozoic rift basins in eastern North America. Particular attention is given to the geometry of border fault systems and associated structures, especially along-strike variability. The relationship between structural geology and stratigraphy is used to infer the evolution of the rift basins. Finally, the nature of the linkage of basins within the rift complex is examined and compared to that of the wellstudied East African rift system. NOMENCLATURE The border fault system (BFS) of a half graben refers to the network of normal faults bounding the asymmetric basin (Figure 2a); movement on these faults was largely responsible for the formation of the basin. Because the exact slip direction on most of the boundary faults is difficult to determine and some boundary faults likely experienced significant strike slip, B FS is used in the general sense for the primary basinbounding fault system regardless of the nature of slip along it. Longitudinal structures or profiles are oriented parallel to the BFS; transverse structures or profiles are oriented perpendicular to the BFS (Figure 2c). Because the BFS commonly consists of multiple faults, the term segment refers to an individual fault within the BFS. As the geometry of the faults at depth is poorly constrained, segmentation is based exclusively on the map view trace of the BFS. Following the scheme used to define the segmentation of seismically active faults [e.g., Zhang et al., 1991 ], segment boundaries are marked by changes in strike as well as offsets or overlaps (Figures 2b and 2c). For overlapping faults, a common segment boundary may be placed in the center of the region of overlap. The relatively unfaulted blocks of rock located between overlapping fault segments are called ramps by Kelley [1979], fault bridges by Ramsay and Huber [1987] and relay ramps by Larsen [1988], Morley et al. [1990], and Peacock and Sanderson [1991]. Where such structures occur in extensional basins, synrift strata unconformably overlap prerift rocks on relay ramps (Figure 2c) [e.g., Larsen, 1988]. In regions of overlapping or subparallel faults, the bottom of the basin may step down along progressively more basinwardsituated faults. The blocks between the faults are termed riders by Gibbs [1984] (Figure 2a). Schlische: Triassic-Jurassic Continental Rift System 1027 Ramping margin refers to the relatively unfaulted basin margin that generally dips toward the BFS (Figure 2a). The intersection of this margin with the Earth's surface is the prerift-synrift contact. Prerift rocks form the "basement" to the basins; synrift rocks refer to the basin fill. Several basins are composed of smaller or structurally distinct subbasins. The Fundy basin (Figure 3a) is subdivided into the northeast trending Fundy and Chignecto subbasins and the east trending Minas subbasin. The Deerfield and Hartford subbasins form the Connecticut Valley basin (Figure 4a). The Deep River basin (Figure 6c) consists of the Durham, Sanford, and Wadesboro subbasins. 75 ø 45" North America 65 c 40 ø Atlantic Ocean MESOZOIC BASINS evolution, Philos. Trans. R. Soc. London, A305, 325-338, 1982.
... Rollover Folds Associated with Detached Normal Faults Rollover folds (Figure 5) are common wi... more ... Rollover Folds Associated with Detached Normal Faults Rollover folds (Figure 5) are common within thick sedimentary successions associated with pas-sive margins, notably the Gulf Coast region and the Niger delta (see references and examples in Bally et ...
The Hopewell fault, which generally strikes northeast and dips to the southeast, is a predominant... more The Hopewell fault, which generally strikes northeast and dips to the southeast, is a predominantly normal fault with a dip separation of 2-3 km located in the Newark rift basin of New Jersey. In order to define the geometry of the Hopewell fault and its associated structures as well as the extent to which those structures influenced sedimentation, a 14-km-wide
Groundwater flow is influenced by topography, but in fractured and dipping sedimentary rocks, it ... more Groundwater flow is influenced by topography, but in fractured and dipping sedimentary rocks, it is also influenced by structure. Field evidence indicates that groundwater is older on the downdip side of a stream (asymmetry) and that dip-aligned streams receive more base flow than strike-aligned streams (anisotropy). We present detailed numerical models to evaluate the effects of various factors that influence
The Great Rift Valleys of Pangea in Eastern …, 2003
... North American Rift System Roy W. Schlische Five key developments have contributed signifi-ca... more ... North American Rift System Roy W. Schlische Five key developments have contributed signifi-cantly to our understanding of the structural geology, basin evolution, and tectonic history of the eastern North American rift system: 1. Acquisition of new data. ...
Three end-member models of half-graben development (detachment fault, domino-style, and fault gro... more Three end-member models of half-graben development (detachment fault, domino-style, and fault growth) evolve differently through time and produce different basin-filling patterns. The detachment fault model incorporates a basin-bounding fault that soles into a subhorizontal ...
Special Paper 303: Reconstructing the History of Basin and Range Extension Using Sedimentology and Stratigraphy, 1996
Half-graben-type basins are a fundamental manifestation of displacement on large normal fault sys... more Half-graben-type basins are a fundamental manifestation of displacement on large normal fault systems, and thus are expected to be deepest near their centers and to grow in depth, width, and length through time. Basin growth models predict that progressively younger synextensional strata will onlap basement rocks, especially if sedimentation keeps pace with increasing basin capacity.
Normal fault systems bounding extensional basins are typically adjoined by a series of subbasins ... more Normal fault systems bounding extensional basins are typically adjoined by a series of subbasins separated by intrabasin highs. The strata within these basins form syndepositional anticlines and synclines whose axes are transverse to the strike of the main bounding fault. One possible explanation for these intrabasin highs is that they result from persistent along-strike deficits in fault displacement. Such deficits
Page 1. ABSTRACT A new structural model for the northeast part of the Central Appa-lachian forela... more Page 1. ABSTRACT A new structural model for the northeast part of the Central Appa-lachian foreland and fold-and-thrust belt is based on detailed field mapping, geophysical data, and balanced cross-section analysis. The ...
ABSTRACT The Field Geology course at Rutgers University incor-porates computers in all projects, ... more ABSTRACT The Field Geology course at Rutgers University incor-porates computers in all projects, including the use of an Electronic Total Station (ETS) and portable Global Positioning System (GPS) receivers in collecting field data. The ETS determines the distance and ...
Early Jurassic-age tholeiitic flood basalts of the Newark Supergroup of the eastern United States... more Early Jurassic-age tholeiitic flood basalts of the Newark Supergroup of the eastern United States are interbedded with strata composed of a hierarchy of lake-level sedimentary cycles of Milankovitch climate cycle origin. Based principally on the Newark basin section, known from continuous core, these cycles constrain the duration of the extrusive and associated intrusive event in exposed basins to 580±10 Ky at -201 Ma, immediately postdating the Triassic-Jurassic boundary. Subsurface basalts of the southeastern U.S. and basalts of the early Mesozoic basins of Morocco and Iberia also appear to have been extruded contemporaneously with those of ihe Newark Supergroup. In addition, most if not all, early Mesozoic tholeiitic dikes and plutons in Eastern North America, West Africa, and Iberia were intruded at about the same time.
Fault zones and fault systems have a key role in the development of the Earth's crust. They contr... more Fault zones and fault systems have a key role in the development of the Earth's crust. They control the mechanics and fluid flow properties of the crust, and the architecture of sedimentary deposits in basins. We review key advances in the study of the structure, mechanics and fluid flow properties of fault zones and fault systems. We emphasize that these three aspects of faults are intimately related and cannot be considered in isolation. For brevity, the review is concentrates on advances made primarily in the past 10 years, and also to fault zones in the brittle continental crust. Finally the paper outlines some key areas for future research in this field.
Formed as a major right-lateral fault zone during Paleozoic collisional orogenies and reactivated... more Formed as a major right-lateral fault zone during Paleozoic collisional orogenies and reactivated as a left-oblique system during the early Mesozoic, the east-striking Minas fault zone of Atlantic Canada controlled adjacent sedimentation in the Fundy rift basin, producing a series of synsedimentary microbasins. Northeast-striking boundary faults of the Fundy basin underwent mostly early Mesozoic normal slip and are reactivated Paleozoic thrusts. The adjacent basin has a much thicker section, transverse folds, and synthetic rider blocks. Contrasts in structural and stratigraphic styles are a response to local deformation controlled by reactivated fault zones of differing orientation under consistent northwest-southeast early Mesozoic extension rather than responses to a sequence of changing stress patterns.
Abstract We performed a quantitative comparison of brittle thrust wedge experiments to evaluate t... more Abstract We performed a quantitative comparison of brittle thrust wedge experiments to evaluate the variability among analogue models and to appraise the reproducibility and limits of model interpretation. Fifteen analogue modeling laboratories participated in this benchmark initiative. Each laboratory received a shipment of the same type of quartz and corundum sand and all laboratories adhered to a stringent model building protocol and used the same type of foil to cover base and sidewalls of the sandbox. Sieve structure, sifting height, filling rate, and details on off-scraping of excess sand followed prescribed procedures. Our analogue benchmark shows that even for simple plane-strain experiments with prescribed stringent model construction techniques, quantitative model results show variability, most notably for surface slope, thrust spacing and number of forward and backthrusts. One of the sources of the variability in model results is related to slight variations in how sand is deposited in the sandbox. Small changes in sifting height, sifting rate, and scraping will result in slightly heterogeneous material bulk densities, which will affect the mechanical properties of the sand, and will result in lateral and vertical differences in peak and boundary friction angles, as well as cohesion values once the model is constructed. Initial variations in basal friction are inferred to play the most important role in causing model variability. Our comparison shows that the human factor plays a decisive role, and even when one modeler repeats the same experiment, quantitative model results still show variability. Our observations highlight the limits of up-scaling quantitative analogue model results to nature or for making comparisons with numerical models. The frictional behavior of sand is highly sensitive to small variations in material state or experimental set-up, and hence, it will remain difficult to scale quantitative results such as number of thrusts, thrust spacing, and pop-up width from model to nature.
CITATIONS 77 READS 24 3 authors, including: Some of the authors of this publication are also work... more CITATIONS 77 READS 24 3 authors, including: Some of the authors of this publication are also working on these related projects: Tectonic, astrochronostratigraphic, and biostratigraphic implications of the paleomagnetic polarity reversal and cyclostratigraphy of the Late Triassic Bigoudine Formation (Argana Basin, Morocco) View project Paul E. Olsen Columbia University 231 PUBLICATIONS 6,309 CITATIONS SEE PROFILE All content following this page was uploaded by Paul E. Olsen on 17 December 2016. The user has requested enhancement of the downloaded file. All in-text references underlined in blue are added to the original document and are linked to publications on ResearchGate, letting you access and read them immediately.
Virtually the entire Late Triassic and earliest Jurassic age section of the early Meso-zoic Newar... more Virtually the entire Late Triassic and earliest Jurassic age section of the early Meso-zoic Newark continental rift basin has been recovered in over 6770 m of continuous core as part of the Newark Basin Coring Project (NBCP). Core was collected using an offset drilling method at seven sites in the central part of the basin. The cores span most of the fluvial Stockton Formation, all of the lacustrine Lockatong and Passaic formations , the Orange Mountain Basalt, and nearly all of the lacustrine Feltville Formation. The cores allow for the first time the full Triassic-age part of the Newark basin stratigraphic sequence to be described in detail. This includes the gray, purple, and red, mostly fluvial Stockton Formation as well as the 53 members that make up the lacustrine Lockatong (mostly gray and black) and Passaic (mostly red) formations. The nearly 25% overlap zones between each of the stratigraphically adjacent cores are used to test lateral correlations in detail, scale the cores to one another, and combine them in a 4660-m-thick composite section. This composite shows that the entire post-Stockton sedimentary section consists of a hierarchy of sedimentary cycles, thought to be of Milankovitch climate cycle origin. Lithostratigraphic and magnetostrati-graphic correlations between core overlap zones and outcrops demonstrate that the individual sedimentary cycles can be traced essentially basinwide. The agreement between the cyclostratigraphy and magne-tostratigraphy shows both the cycles and the polarity boundaries to be isochronous horizons. Detailed analysis of the Newark basin shows that high-resolution cyclos-tratigraphy is possible in lacustrine, primarily red-bed rift sequences and provides a fine-scale framework for global correlations and an understanding of continental tropical climate change. This paper is dedicated to the late Alfred Froelich.
The Argana rift basin of Morocco and the Fundy rift basin of the Maritime Provinces of Eastern Ca... more The Argana rift basin of Morocco and the Fundy rift basin of the Maritime Provinces of Eastern Canada are on the conjugate margins of the central Atlantic Ocean. In the Late Triassic and Early Jurassic these basins lie at similar paleolatitudes within the same great rift system. A comparison of the depositional-and tectono-stratigraphy reveal strong similarities, much greater that those shared between the Fundy basin and other rifts in eastern North America. Both the Argana and Fundy basins are comprised of four, mostly unconformity-bound, tectonostratigraphic sequences (TS I-IV) probably controlled by pulses of extension: TS I, is Permian in age and the depositional facies of the Argana basin looks more humid than the age equivalent in the Fundy basin and the latter may not be a rift sequence; TS II, is early Late Triassic (Carnian) in age and is the most humid looking facies in both basins; TS Ill, is late Late Triassic (Norian and Rhaetian) in age and is much more arid in both basins with abundant aeolianites and evaporites; TS IV, is latest Triassic and earliest Jurassic (late Rhaetian-early Hettangian) and shows an increase in the range of variability in climate-sensitive facies-its basal part contains the Triassic-Jurassic boundary an overlying basalt flow sequence and additional fluvial and lacustrine strata on top. The dramatic similarity in both facies and sequence stratigraphy between the Argana and Fundy basins, at least during the Triassic, argues for similar tectonic control, restricted to that latitudinal swath of Pangea, as well as similar paleoclimate.
The Argana rift basin of Morocco and the Fundy rift basin of the Maritime Provinces of Eastern Ca... more The Argana rift basin of Morocco and the Fundy rift basin of the Maritime Provinces of Eastern Canada are on the conjugate margins of the central Atlantic Ocean. In the Late Triassic and Early Jurassic these basins lie at similar paleolatitudes within the same great rift system. A comparison of the depositional-and tectono-stratigraphy reveal strong similarities, much greater that those shared between the Fundy basin and other rifts in eastern North America. Both the Argana and Fundy basins are comprised of four, mostly unconformity-bound, tectonostratigraphic sequences (TS I-IV) probably controlled by pulses of extension: TS I, is Permian in age and the depositional facies of the Argana basin looks more humid than the age equivalent in the Fundy basin and the latter may not be a rift sequence; TS II, is early Late Triassic (Carnian) in age and is the most humid looking facies in both basins; TS Ill, is late Late Triassic (Norian and Rhaetian) in age and is much more arid in both basins with abundant aeolianites and evaporites; TS IV, is latest Triassic and earliest Jurassic (late Rhaetian-early Hettangian) and shows an increase in the range of variability in climate-sensitive facies-its basal part contains the Triassic-Jurassic boundary an overlying basalt flow sequence and additional fluvial and lacustrine strata on top. The dramatic similarity in both facies and sequence stratigraphy between the Argana and Fundy basins, at least during the Triassic, argues for similar tectonic control, restricted to that latitudinal swath of Pangea, as well as similar paleoclimate.
The Orpheus basin of offshore eastern Canada formed before opening of the North Atlantic Ocean. W... more The Orpheus basin of offshore eastern Canada formed before opening of the North Atlantic Ocean. We have identified four distinct tectonostratigraphic packages (A-D) associated with the basin's early development. Packages A, B, C, and D represent Paleozoic prerift strata and basement, Middle Triassic to Early Jurassic synrift strata, Early to Middle Jurassic postrift strata, and Middle to Late Jurassic postrift strata, respectively. The middle part of package B is likely salt. Rifting began by the Late Triassic and continued into the Early Jurassic. Regional shortening occurred after rifting (during the Early to Middle Jurassic), producing salt-cored detachment folds, detached thrust faults, and regional uplift and erosion. Tectonic quiescence followed shortening, leading to widespread deposition. Postrift salt movement resumed during the Middle to Late Jurassic.
Mesozoic rift basins in eastern North America formed during continental extension associated with... more Mesozoic rift basins in eastern North America formed during continental extension associated with the separation of North America and Africa. These basins locally overprint the Appalachian orogen and involve the extensional reactivation of Paleozoic faults. Half graben are thought to have formed where Mesozoic extension was subperpendicular to orogenic strike. Transtensional basins formed where the extension was more oblique. Segmented border fault systems and predominanfiy synthetic intrabasinal faults characterize the half graben. These basins resemble elongate synclines in longitudinal section; this geometry resulted from border-fault displacement that was greatest near the center of the fault and decreased toward both ends. Large-scale segmentation of some border fault systems resulted in the formation of multiple synclinal subbasins separated by transverse anticlines at segment boundaries, where fault displacement was less. As displacement increased on individual fault segments, the faults and associated basins grew in length, perhaps linking originally isolated basins. Smaller-scale fault segmentation resulted in the formation of relay ramps, rider blocks, and transverse folds. Some transverse synclines are located near the centers of fault segments, and related anticlines are located at segment boundaries. Adjacent half graben units within larger rift zones do not alternate polarity along strike and are generally not linked via accommodation zones, as in the East African rift system. Strike-slip-dominated basins are characterized by a network of strike-slip and normal faults, and are shallower and narrower than dip-slip-dominated basins. INTRODUCTION Fault-bounded sedimentary basins, typically half graben, are a fundamental manifestation of continental extension [e.g., Bally, 1982; Wernicke and Burchfiel, 1982; Anderson et al., 1983; Jackson and McKenzie, 1983; Gibbs, 1984; Rosendahl, 1987] and are also the prevalent architecture of transtensional regimes, at least within the Tanganyika-Rukwa-Malawi system in East Africa [Rosendahl et al., 1992; Scott et al., 1992]. Numerous basins formed along the margins of the incipient North Atlantic Ocean during the Mesozoic breakup of Pangea (Figure la) [Van Houten, 1977; Froelich and Olsen, 1984; Tankard and Balkwill, 1989]. In eastern North America, basins crop out over a distance of > 1700 km; other basins are concealed beneath coastal plain deposits and the continental shelf (Figure lb) (see recent summaries by Froelich and Robinson [ [ 1988]. The exposed basins are filled with thousands of meters of exclusively nonmarine strata [e.g., Smoot, 1985; Manspeizer et al., 1989; Olsen et al., 1989; Smoot, 1991] as well as tholeiitic lava flows and diabase intrusions [e.g., Froelich and Gottfried, 1988; Puffer and Philpotts, 1988; Manspeizer et al., 1989; Puffer and Ragland, 1992], most of which crystallized at-200 Ma [Sutter, 1988; Dunning and Hodych, 1990]. Biostratigraphic dating indicates that preserved basin strata range in age from Middle Triassic to Early Jurassic (Table 1) [Comet and Olsen, 1985; Olsen et al., 1989]. Rift basins in eastern North America locally overprint the Appalachian orogen and exhibit parallelism with Paleozoic contractional structures (Figure lb) [e.g., Lindholm, 1978; Swanson, 1986; Ratcliffe et al., 1986]. The exposed rift basins are situated landward of the hinge zone of the continental margin; this region experienced considerably less crustal thinning than did the seaward region [Klitgord et al., 1988]. Consequently, many of these landward basins were not deeply buried by postrift strata and therefore remain accessible today. This paper examines the similarities and differences in the architecture of exposed Mesozoic rift basins in eastern North America. Particular attention is given to the geometry of border fault systems and associated structures, especially along-strike variability. The relationship between structural geology and stratigraphy is used to infer the evolution of the rift basins. Finally, the nature of the linkage of basins within the rift complex is examined and compared to that of the wellstudied East African rift system. NOMENCLATURE The border fault system (BFS) of a half graben refers to the network of normal faults bounding the asymmetric basin (Figure 2a); movement on these faults was largely responsible for the formation of the basin. Because the exact slip direction on most of the boundary faults is difficult to determine and some boundary faults likely experienced significant strike slip, B FS is used in the general sense for the primary basinbounding fault system regardless of the nature of slip along it. Longitudinal structures or profiles are oriented parallel to the BFS; transverse structures or profiles are oriented perpendicular to the BFS (Figure 2c). Because the BFS commonly consists of multiple faults, the term segment refers to an individual fault within the BFS. As the geometry of the faults at depth is poorly constrained, segmentation is based exclusively on the map view trace of the BFS. Following the scheme used to define the segmentation of seismically active faults [e.g., Zhang et al., 1991 ], segment boundaries are marked by changes in strike as well as offsets or overlaps (Figures 2b and 2c). For overlapping faults, a common segment boundary may be placed in the center of the region of overlap. The relatively unfaulted blocks of rock located between overlapping fault segments are called ramps by Kelley [1979], fault bridges by Ramsay and Huber [1987] and relay ramps by Larsen [1988], Morley et al. [1990], and Peacock and Sanderson [1991]. Where such structures occur in extensional basins, synrift strata unconformably overlap prerift rocks on relay ramps (Figure 2c) [e.g., Larsen, 1988]. In regions of overlapping or subparallel faults, the bottom of the basin may step down along progressively more basinwardsituated faults. The blocks between the faults are termed riders by Gibbs [1984] (Figure 2a). Schlische: Triassic-Jurassic Continental Rift System 1027 Ramping margin refers to the relatively unfaulted basin margin that generally dips toward the BFS (Figure 2a). The intersection of this margin with the Earth's surface is the prerift-synrift contact. Prerift rocks form the "basement" to the basins; synrift rocks refer to the basin fill. Several basins are composed of smaller or structurally distinct subbasins. The Fundy basin (Figure 3a) is subdivided into the northeast trending Fundy and Chignecto subbasins and the east trending Minas subbasin. The Deerfield and Hartford subbasins form the Connecticut Valley basin (Figure 4a). The Deep River basin (Figure 6c) consists of the Durham, Sanford, and Wadesboro subbasins. 75 ø 45" North America 65 c 40 ø Atlantic Ocean MESOZOIC BASINS evolution, Philos. Trans. R. Soc. London, A305, 325-338, 1982.
... Rollover Folds Associated with Detached Normal Faults Rollover folds (Figure 5) are common wi... more ... Rollover Folds Associated with Detached Normal Faults Rollover folds (Figure 5) are common within thick sedimentary successions associated with pas-sive margins, notably the Gulf Coast region and the Niger delta (see references and examples in Bally et ...
The Hopewell fault, which generally strikes northeast and dips to the southeast, is a predominant... more The Hopewell fault, which generally strikes northeast and dips to the southeast, is a predominantly normal fault with a dip separation of 2-3 km located in the Newark rift basin of New Jersey. In order to define the geometry of the Hopewell fault and its associated structures as well as the extent to which those structures influenced sedimentation, a 14-km-wide
Groundwater flow is influenced by topography, but in fractured and dipping sedimentary rocks, it ... more Groundwater flow is influenced by topography, but in fractured and dipping sedimentary rocks, it is also influenced by structure. Field evidence indicates that groundwater is older on the downdip side of a stream (asymmetry) and that dip-aligned streams receive more base flow than strike-aligned streams (anisotropy). We present detailed numerical models to evaluate the effects of various factors that influence
The Great Rift Valleys of Pangea in Eastern …, 2003
... North American Rift System Roy W. Schlische Five key developments have contributed signifi-ca... more ... North American Rift System Roy W. Schlische Five key developments have contributed signifi-cantly to our understanding of the structural geology, basin evolution, and tectonic history of the eastern North American rift system: 1. Acquisition of new data. ...
Three end-member models of half-graben development (detachment fault, domino-style, and fault gro... more Three end-member models of half-graben development (detachment fault, domino-style, and fault growth) evolve differently through time and produce different basin-filling patterns. The detachment fault model incorporates a basin-bounding fault that soles into a subhorizontal ...
Special Paper 303: Reconstructing the History of Basin and Range Extension Using Sedimentology and Stratigraphy, 1996
Half-graben-type basins are a fundamental manifestation of displacement on large normal fault sys... more Half-graben-type basins are a fundamental manifestation of displacement on large normal fault systems, and thus are expected to be deepest near their centers and to grow in depth, width, and length through time. Basin growth models predict that progressively younger synextensional strata will onlap basement rocks, especially if sedimentation keeps pace with increasing basin capacity.
Normal fault systems bounding extensional basins are typically adjoined by a series of subbasins ... more Normal fault systems bounding extensional basins are typically adjoined by a series of subbasins separated by intrabasin highs. The strata within these basins form syndepositional anticlines and synclines whose axes are transverse to the strike of the main bounding fault. One possible explanation for these intrabasin highs is that they result from persistent along-strike deficits in fault displacement. Such deficits
Page 1. ABSTRACT A new structural model for the northeast part of the Central Appa-lachian forela... more Page 1. ABSTRACT A new structural model for the northeast part of the Central Appa-lachian foreland and fold-and-thrust belt is based on detailed field mapping, geophysical data, and balanced cross-section analysis. The ...
ABSTRACT The Field Geology course at Rutgers University incor-porates computers in all projects, ... more ABSTRACT The Field Geology course at Rutgers University incor-porates computers in all projects, including the use of an Electronic Total Station (ETS) and portable Global Positioning System (GPS) receivers in collecting field data. The ETS determines the distance and ...
Early Jurassic-age tholeiitic flood basalts of the Newark Supergroup of the eastern United States... more Early Jurassic-age tholeiitic flood basalts of the Newark Supergroup of the eastern United States are interbedded with strata composed of a hierarchy of lake-level sedimentary cycles of Milankovitch climate cycle origin. Based principally on the Newark basin section, known from continuous core, these cycles constrain the duration of the extrusive and associated intrusive event in exposed basins to 580±10 Ky at -201 Ma, immediately postdating the Triassic-Jurassic boundary. Subsurface basalts of the southeastern U.S. and basalts of the early Mesozoic basins of Morocco and Iberia also appear to have been extruded contemporaneously with those of ihe Newark Supergroup. In addition, most if not all, early Mesozoic tholeiitic dikes and plutons in Eastern North America, West Africa, and Iberia were intruded at about the same time.
Fault zones and fault systems have a key role in the development of the Earth's crust. They contr... more Fault zones and fault systems have a key role in the development of the Earth's crust. They control the mechanics and fluid flow properties of the crust, and the architecture of sedimentary deposits in basins. We review key advances in the study of the structure, mechanics and fluid flow properties of fault zones and fault systems. We emphasize that these three aspects of faults are intimately related and cannot be considered in isolation. For brevity, the review is concentrates on advances made primarily in the past 10 years, and also to fault zones in the brittle continental crust. Finally the paper outlines some key areas for future research in this field.
Formed as a major right-lateral fault zone during Paleozoic collisional orogenies and reactivated... more Formed as a major right-lateral fault zone during Paleozoic collisional orogenies and reactivated as a left-oblique system during the early Mesozoic, the east-striking Minas fault zone of Atlantic Canada controlled adjacent sedimentation in the Fundy rift basin, producing a series of synsedimentary microbasins. Northeast-striking boundary faults of the Fundy basin underwent mostly early Mesozoic normal slip and are reactivated Paleozoic thrusts. The adjacent basin has a much thicker section, transverse folds, and synthetic rider blocks. Contrasts in structural and stratigraphic styles are a response to local deformation controlled by reactivated fault zones of differing orientation under consistent northwest-southeast early Mesozoic extension rather than responses to a sequence of changing stress patterns.
Abstract We performed a quantitative comparison of brittle thrust wedge experiments to evaluate t... more Abstract We performed a quantitative comparison of brittle thrust wedge experiments to evaluate the variability among analogue models and to appraise the reproducibility and limits of model interpretation. Fifteen analogue modeling laboratories participated in this benchmark initiative. Each laboratory received a shipment of the same type of quartz and corundum sand and all laboratories adhered to a stringent model building protocol and used the same type of foil to cover base and sidewalls of the sandbox. Sieve structure, sifting height, filling rate, and details on off-scraping of excess sand followed prescribed procedures. Our analogue benchmark shows that even for simple plane-strain experiments with prescribed stringent model construction techniques, quantitative model results show variability, most notably for surface slope, thrust spacing and number of forward and backthrusts. One of the sources of the variability in model results is related to slight variations in how sand is deposited in the sandbox. Small changes in sifting height, sifting rate, and scraping will result in slightly heterogeneous material bulk densities, which will affect the mechanical properties of the sand, and will result in lateral and vertical differences in peak and boundary friction angles, as well as cohesion values once the model is constructed. Initial variations in basal friction are inferred to play the most important role in causing model variability. Our comparison shows that the human factor plays a decisive role, and even when one modeler repeats the same experiment, quantitative model results still show variability. Our observations highlight the limits of up-scaling quantitative analogue model results to nature or for making comparisons with numerical models. The frictional behavior of sand is highly sensitive to small variations in material state or experimental set-up, and hence, it will remain difficult to scale quantitative results such as number of thrusts, thrust spacing, and pop-up width from model to nature.
CITATIONS 77 READS 24 3 authors, including: Some of the authors of this publication are also work... more CITATIONS 77 READS 24 3 authors, including: Some of the authors of this publication are also working on these related projects: Tectonic, astrochronostratigraphic, and biostratigraphic implications of the paleomagnetic polarity reversal and cyclostratigraphy of the Late Triassic Bigoudine Formation (Argana Basin, Morocco) View project Paul E. Olsen Columbia University 231 PUBLICATIONS 6,309 CITATIONS SEE PROFILE All content following this page was uploaded by Paul E. Olsen on 17 December 2016. The user has requested enhancement of the downloaded file. All in-text references underlined in blue are added to the original document and are linked to publications on ResearchGate, letting you access and read them immediately.
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Papers by Roy Schlische