The Structural Geology and Tectonics Group at Rutgers is committed to teaching (undergraduate and graduate), research, and service. Our courses are comprehensive, hands-on, and utilize the results of our research. The goal of our research is to understand the geometry, evolution and mechanics of normal-fault systems and associated structures (mainly fault-related extensional folds); the mechanics of continental rifting, evolution of rift basins, and development of passive margins; and application to sedimentary, petroleum, and hydrogeologic systems. Our approach is multi-faceted, and incorporates field studies, experimental physical modeling, and interpretation of seismic-reflection profiles. Recent and ongoing field studies of rift systems and extensional faults involve areas of exceptional exposure (Fundy rift basin, southeastern Canada; oblique rift zones and transfer zones in Iceland; population of small normal faults in the Solite Quarry, Danville rift basin, Virginia, USA) and areas where multiple data sets are available (seismic reflection profiles, well data, and outstanding outcrops in the Fundy basin; seismic reflection profiles, scientific cores, and outcrops in the Newark basin, New York, New Jersey and Pennsylvania, USA).
Current Students and Assistants: Michael Flite, Sean Kinney, Max Needle, Ashta Rao, Christina Sheng, Cesar Sequeira, Natalie Stier, Kathleen Warrell
Former student associates: Rolf V. Ackermann, Mark Baum, Amy Clifton, Trent DellOro, Michael Durcanin, Jennifer A. Elder Brady, Etikha, Seth D. Fankhauser, Martin D. Finn, Bari Hanafi, Gregory D. Herman, Amber Granger, Sean Harrison, Alissa Henza, Triyani Hidayah, Brian D. Jones, Zev Ladin, Michael Lovich, Douglas L. Musser, Stefan Muszala, Kevin D. Orabone, Holly Peterson, Jaeson Pieretti, Billy Pilesky, Emily Poorvin, Christian Putra Ginting, Beatriz Serrano Sanchez, Lisa Seunarine, Maria Shakhnovich, Ika Sulistyani, Zulfitriadi Syamsir, Nicholas Tedeschi, Peter Thibodeau, Michael Viersma, Hemal Vora, Jamie Whitlock, and Scott S. Young.
Colleagues: David Anastasio (Lehigh University), Mark H. Anders (Lamont Doherty Earth Observatory, Columbia University), Mark Baum (Chevron), Karen Bemis (Rutgers), Roger Buck (Lamont Doherty Earth Observatory, Columbia University), Amy Clifton (Nordic Volcanologic Institute), Nivaldo Destro (Petrobras), Michael Durcanin (Nexen Petroleum), Richard H. Groshong (3D Structure Research), Alissa Henza (B.H.P. Billiton), Greg Herman (N.J. Geological Survey), Triyani Hidayah (ExxonMobil), Christopher Jackson (Imperial College), Dennis Kent (Rutgers), Vadim Levin (Rutgers), Maryann Love Malinconico (Lafayette College), Don Monteverde (N.J. Geological Survey), Julia Morgan (Rice University), Thorsten Nagel (University of Bonn), Paul E. Olsen (Lamont Doherty Earth Observatory, Columbia University), Frank Pazzaglia (Lehigh University), Ying Reinfelder (Rutgers), David J. Reynolds (ExxonMobil Corp.), Christopher H. Scholz (Lamont Doherty Earth Observatory, Columbia University), Iain Sinclair (Husky Energy), Malin Somby (ExxonMobil U.K.), Sarah Tindall (Kutztown University), Paul Whipp (Statoil)
We gratefully acknowledge the following corporations and organizations who have supported the Structure Group: Seismic-Microtechnology for donating the Kingdom Suite seismic-interpretation software package; Schlumberger for providing Petrel software at a greatly reduced price; Midland Valley for providing the software package 3D Move; ExxonMobil for donating some of the equipment in our experimental modeling lab; TGS-Nopec, ConocoPhillips, and Canada-Nova Scotia Offshore Petroleum Board for providing seismic and other data from the Orpheus and Scotian basins, offshore Canada; Schlumberger for the donation of seismic data from the Jeanne d'Arc basin, offshore Canada; and Husky Energy, ExxonMobil, and Petrobras for financial support of students' research projects and the experimental modeling laboratory. For more information about our supporters and sponsors, please visit their websites by clicking on their hyperlinked names above.
Undergraduate: Structural Geology, Tectonics and Regional Structural Geology, Earth Resources and Global Economics
Graduate: Advanced Structural Geology, Advanced Tectonics, Seminar in Extensional Tectonics, Seminar in Geology: Rift Basins
A. Introduction & Summary
The goal of our research is to understand: 1) the geometry, evolution and mechanics of normal-fault systems and fault-related extensional folds; and 2) the evolution and mechanics of continental rift systems and the development of passive margins. Our approach is multi-faceted, incorporating field studies, scaled experimental modeling, and interpretation of seismic-reflection profiles. The results of our research are applicable to sedimentary, petroleum, and hydrogeologic systems and to seismic-hazard assessment.
We have 67 published articles. According to the ISI Web of Science, the top 16 articles and book were cited over 700 times since 1994. Furthermore, over 30 textbooks and other scholarly books cited our research, according to Amazon.com. We have obtained $727,494 from the National Science Foundation and the Petroleum Research Fund of the American Chemical Society; $90,000 in industry contracts and grants; industry donations of permanent equipment valued at $25,000; annual software renewals valued at $750,000; and $68,077 in university money for use by the Department of Geological Sciences. We have mentored ~22 graduate students (all of whom are professionally employed; one was awarded a prestigious NSF postdoctoral fellowship) and 10 undergraduates who completed senior theses and independent study projects.
B. Experimental Modeling and Seismic-Interpretation Labs
The Rutgers Experimental Modeling Laboratory is a world-class facility for studying the 3D geometry and evolution of geologic structures. Our state-of-the-art laboratory is designed specifically for scaled modeling. With our versatile equipment, we can simulate most structural styles, including basement-involved, detached, and distributed extension; shortening; strike-slip, and oblique deformation; and salt tectonics. Our equipment is specially engineered to allow us to change the displacement direction during a model run (e.g., two phases of extension; extension followed by shortening, i.e., basin inversion). We use a variety of scaled modeling materials (dry sand, wet clay, putty), but specialize in layered clay models. We pioneered the use of serial sectioning that allows construction of 3D representations of fault surfaces, folded horizons, and unconformities, etc. (Schlische et al. 2002, A51) (A=article [complete list>>], Th=thesis, C=abstract of conference proceedings (recent abstracts>>]). The Rutgers Modeling Lab was the only U.S. modeling lab to participate in a series of 'benchmark' experiments of extension at a recent international conference on geologic modeling (see Schreurs et al. 2006 A62). Prof. G. Mountain and we also supervise a seismic-interpretation laboratory equipped with Windows and Unix workstations and software (donated by industry) for 2D and 3D seismic projects.
C. Fault Geometries, Populations, and Associated Structures
Our prior work on this topic has addressed segmentation of basin-bounding normal-fault systems (Anders & Schlische 1994 A22, Schlische & Anders 1996 A34), the scaling relationship between fault length and displacement (Schlische et al. 1996 A35), the size distribution of faults within natural and experimental fault populations (e.g., Ackermann & Schlische 1997 A38, Clifton et al. 2000 A46; Ackermann et al. 2001 A49; Clifton and Schlische 2001, 2003 A48, A55, Ackermann et al. 2003 A54), and geologic evidence of stress-reduction shadows around faults (Ackermann & Schlische 1997 A38). Research on fault-related folding (Withjack & Drickman Pollock 1984 A5, Withjack et al. 1990 A12, Schlische 1995 A28, Withjack et al. 1995 A27, Withjack & Callaway 2000 A47; Withjack et al. 2002 A50, Schlische 2003 A53, Withjack & Schlische 2006 A63) has emphasized that folds do not always indicate shortening and that displacement variations on faults and fault-growth are critical controls on fold geometry. Our research group is investigating the 3-D geometries of fault surfaces and displacement fields. For example, Granger (2002 Th17, 2005 Th22) and Granger et al. (2002 C57, 2005 C67, 2006 C73) used closely spaced serial cross sections of clay models (see section B) to determine that all normal faults in our clay models contain grooves or undulations that parallel the slip vector. Larger-scale undulations are related to linkage of non-coplanar fault segments, and smaller-scale undulations are probably related to the process of fault growth into a process zone of small-scale fractures at the propagating fault tip-line. Serial sectioning is also viable for exceptionally well-preserved, very small normal faults from the Solite Quarry (Schlische et al. 1996 A35). Future work will investigate temporal changes in fault activity within a large population of faults, addressing such issues as stress-enhancement and stress-reduction zones around faults, strain localization, and the formation of new faults when preexisting faults lock-up as high displacements can no longer be supported.
D. Basin Inversion on Passive Margins
Basin inversion (extension followed by shortening) is little studied in North America. For example, our group was the only U.S. representative at a recent international conference on inversion on passive margins held at the Geological Society of London (Withjack et al. 2005 C70). Previous work has shown that large-magnitude inversion structures are present in the Fundy basin (Withjack et al. 1995 A29). We also established that inversion is broadly contemporaneous with the rift-drift transition and that this transition was diachronous along the central North Atlantic passive margin (Withjack et al. 1998 A41, Schlische et al. 2003 A56, Withjack et al. 2005 A59). Several uncertainties remain.
1) Timing of inversion. For the northern segment of the rift system, all geological data indicate that the inversion postdates synrift sedimentation, but the lack of postrift deposits over the exposed rift basins precludes constraining its age further. Postrift deposits are present offshore, and we anticipate that seismic data from the continental margin will prove useful, provided that the effects of salt-related deformation can be accounted for. We have established good contacts with oil companies working in offshore Canada, where industry seismic data are publicly released after a few years.
2) Shortening direction responsible for inversion. In previous work, we suggested that the shortening direction during inversion was approximately oriented NW-SE (Withjack et al. 1995 A29, 1998 A41). This direction is likely correct for the southern segment of the margin, where dikes provide an unbiased snapshot of the state of stress during the rift-drift transition (e.g., Schlische et al. 2003 A56). Along the northern segment of the margin, our estimate of the shortening direction is based on inversion structures that originated during the extensional phase and whose orientation may strongly bias the inferred shortening direction. Baum (2002 Th18, 2006 Th23) and Baum et al. (2003 C60, 2007 in review) mapped the 3D geometry of inversion structures in the Fundy basin using seismic and field data; the goal of this work is to identify structures that may not be biased by the earlier extensional deformation, which is more likely for smaller-scale faults and deformation zones (Elder Brady 2003 Th20, Elder Brady et al. 2003 C59). We are also using experimental models of oblique extension and oblique shortening (Baum et al. 2004 C62, 2007 in prep., 2006 Th23) to constrain the shortening direction. Only secondary structures formed during shortening following oblique extension provide relatively well-constrained estimates of the shortening direction, N-S to NE-SW.
3) Relationship to CAMP. The Central Atlantic Magmatic Province (CAMP) is a large igneous province (LIP). CAMP rocks are well dated along the northern segment of the margin (Olsen et al. 1996 A32), but their age (~200 Ma) is 15-25 million years older than the rift-drift transition. Subsurface, apparently postrift basalt flows and seaward-dipping reflectors (all part of the LIP and volcanic passive margin) in the southeastern U.S. have been linked to CAMP, and, if our hypothesis of diachronous initiation of seafloor spreading is correct, should be coeval with the rift-drift transition along the southern segment of the margin (e.g., Schlische et al. 2003 A56). These hypotheses can be tested through isotopic dating of the igneous rocks. Highly weathered samples of the subsurface basalts likely will not yield reliable dates, but untilted sills (i.e., intrusion after rift-related deformation) from Georgia may resolve this issue. Sampling of the seaward-dipping reflectors requires deep drilling and an international research effort; a scientific conference (Pangean Pole-to-Pole Coring Project, funded by NSF; Schlische et al. 1999 A43) identified this as a priority.
4) Cause of basin inversion. The passive-margin setting of the inverted rift basins means that the cause of the shortening is enigmatic. Possible causes include ridge push, continental resistance to plate motion, and forces generated by active asthenospheric upwelling (which is required to generate the seaward-dipping reflectors and the LIP) (e.g., Withjack et al. 1998 A41). The timing and direction of the shortening (see above) are critical to constraining the causal mechanism.
E. Experimental Structural Geology
In recent years, our research has focused on using fault-population statistics to examine the temporal evolution of the fault systems (e.g., Ackermann et al. 2001 A49; Clifton & Schlische 2001 A48), modeling the secondary structures associated with oblique deformation (e.g., Withjack & Jamison 1986 A7; Clifton et al. 2000 A46; Clifton & Schlische 2001 A48, 2003 A55, Schlische et al. 2002 A34), the evolution of fault-bend folds based on geometric and experimental modeling (Withjack & Schlische 2006 A46). Other experimental work has examined the origin of domes (Withjack & Sheiner 1982 A4), forced folds and fault-propagation folds (Withjack et al. 1990 A12, Withjack & Callaway 2000 A47), rollover structures (Withjack & Islam 1993 A18, Withjack & Peterson 1993 A19, Withjack et al. 1995 A27), and orthogonal basin inversion (Eisenstadt & Withjack 1995 A26). Ongoing and future projects include:
1) Origin of dip domains and transfer zones. Normal faults may exhibit a conjugate geometry or, more commonly, may belong to dip domains (in which all or most faults in a region dip in the same direction, i.e., domino-style or bookshelf faulting) separated by accommodation zones or transfer zones. Our work (Schlische & Withjack, 2007, in review; Schlische et al. 2005 C69) suggests dip domains do not require the presence of preexisting structure or a dipping detachment fault, that the trend of accommodation zones and transfer zones are not necessarily related to the extension direction, that early formed faults perturb the stress field and control the nucleation of faults with the same dip direction, and that accommodation zones consist of the overlapping tips of faults from adjacent dip domains along with folding and small-scale faulting.
2) Deformation rate: Fundamental research in the geosciences concerns determining the rates of geologic processes, which can, for example, affect estimates of earthquake recurrence intervals and seismic-hazard assessment. Our research (Schlische et al. 2002 C58) suggests that the regional deformation rate may be an independent variable that controls the size and spatial distribution of faults. Experiments with wet clay indicate that the number of faults increases and the displacement and spacing decrease with increasing deformation rate.
3) Comparisons with numerical models. We are conducting this work in conjunction with Roger Buck and colleagues at Columbia University. We are investigating how 'faults' develop in numerical and experimental models with the same boundary conditions; our goal is to improve the numerical models themselves and the input parameters, and to determine which, if any, structures are related to unforseen, undesirable edge effects. We will also explore the applicability of different types of numerical models. For example, finite-difference/finite-element models with elastic-viscous-plastic rheologies are better for distributed deformation; discrete element and tri-shear models models are better for studying fault-propagation folding, and geometric models are best for studying detached extension.
4) Other current projects include: (a) oblique basin inversion (Baum et al. 2004 C62, 2007 in prep., 2006 Th23; see section D2 above); (b) effect of basal boundary condition on fault geometry and displacement distribution (Granger et al. 2005 C67, 2005 Th22, 2006 C73); (c) effect of mechanical stratigraphy on fault populations and differences between sand and clay (Withjack & Schlische 2006 A63, Withjack et al. 2007 A65, Henza in prep. Th25); (d) experiments involving two different phases of extensional deformation (the first phase creates a network of faults, the second creates new faults and potentially reactivates preexisting ones), and (e) collaborative research with Dr. Christopher Jackson (Imperial College of London) to construct 3D representations (structure-contour maps, isopach maps, 3D renderings) of structures using structural modeling software; we then restore these structures to earlier stages of deformation, which can be then compared to available photos of the evolving structures in plan view.
F. Structural Controls on Sedimentary Systems
Previous work has focused on large-scale thickness and facies changes in the Newark and related rift basins (Schlische & Olsen 1990 A14, Schlische 1990 Th5, 1991 A15, 1992 A16, 1993 A21, Anders & Schlische 1994 A22, Schlische & Anders 1996 A34, Withjack et al. 2002 A50, Schlische 2003 A53). Specifically, a basin growing in cumulative capacity as a result of fault growth coupled with a fixed supply rate of sediment and water yields a tripartite stratigraphy (initial fluvial deposits, deepening upward lacustrine deposits, and shallowing-upward lacustrine deposits) and predictable trends in sediment-accumulation rates, which vary with location in the basin; the model predictions are mostly confirmed by cyclostratigraphically calibrated sedimentation rates from more than 25,000 feet of core obtained by the Newark Basin Coring Project (Olsen et al. 1996a, b A32-33, Schlische 2003 A53). Additional work focuses on growth deposits associated with a number of different rift-basin styles (basins bounded by a reactivated thrust fault, basins associated with upward-propagating faults through salt; and basins associated with oblique extension and basin inversion; Withjack et al. 2002 A50). Experimental models will provide additional information on the characteristics of growth deposits for aiding in discriminating among pre-, syn-, and post-deformational units, which is not always straightforward (Withjack & Schlische 2005 C68), as well as the topography of deformed regions.
G. Fractures and Hydrogeology
Outcrop and core studies in the Newark basin have focused on (1) the geometry and spatial distribution of joints (Jones 1994 Th8, Finn 1996 Th10; Fankhauser 1996 Th15, Pieretti 2004 Th21), (2) application to groundwater hydrology (Orabone 1997 Th14, Herman 1996 Th11, Mike Serfes 2005, Ph.D. thesis) and geophysics (Muszala et al. 1998 A40), and (3) structural controls on fluvial geomorphology (Ackermann 1997 Th Color 12). Joints (not filled with vein material) and bedding-plane partings provide conduits for fluid-flow at intermediate depths, but shallow flow paths are governed mainly by topographic slopes. These results constrain Modflow hydrologic models of fluid-flow in fractured, dipping strata (Fan et al. 2007 A64).
H. Synergy: Teaching and Service
Our own research has benefited tremendously from the research conducted by numerous graduate and undergraduate students. Numerous articles and abstracts are co-authored with current or former students. Our group's experimental modeling research is used in the undergraduate Structural Geology (C74) and Field Geology courses, as well as several graduate courses including Advanced Structural Geology and Advanced Tectonics. Students run three experimental models in the Structural Geology course. QuickTime movies and plan-view and cross-sectional images of various experiments are posted in a collection of structural geology images. Research on the Newark basin forms the basis of a Structure-Stratigraphy field trip, and is used in four field guides (A10, A20, A57, A60). It was also discussed in an article about integrating computers into the field geology course (Schlische & Ackermann 1998 A39); and is the subject of three web essays. Research on the Fundy basin and the diachronous rift-drift transition and basin inversion forms the basis of all mapping exercises in the Field Geology course (see Schlische & Withjack in prep.). Our research on structural geology over the last 25 years has allowed us to attend numerous conferences and workshops as well as to review many scientific papers and proposals. MEOW was an associate editor for AAPG Bulletin and the Geological Society of America Bulletin, and is a past-president of GSA's Structural Geology and Tectonics Division. RWS served as head reviewer of structural-geology terms for AGI's (2005) Glossary of Geology.
index.htm -- Revised: 8 September 2008