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Anonymous, 1991, Drilling completed in Newark basin. CDS News, College of Geosciences, Texas A&M University, College Station Texas.

Ten wells at six sites were continuously cored during the winter and spring of 1990/1991 in the Newark Basin of central New Jersey. ... The 19,610 ft of Late Triassic to earliest Jurassic age core is critical for climatic, rift basin, and paleomagnetic evaluation. Drilling was performed by the Amoco Production Company SHADS group, with real time core analysis provided by their automated Geological Evaluation Modules. ... The project was funded by the NSF/EAR in a grant to Paul Olsen and Dennis Kent, both of the Lamont-Doherty Geological Observatory of Columbia University. ... [no abstract with original paper] back to bibliography

Baker, G. S., 1994, An Examination of Triassic Cyclostratigraphy in the Newark Basin from Shallow Seismic Profiles and Geophysical Logs. Masters Thesis, Lehigh Univesrity, Lehigh, PA., 145 p.

During the early Mesozoic breakup of Pangea a series of rift basins formed along the eastern coast of present-day North America. The Newark Basin in New York, Pennsylvania, and New Jersey, is one of the largest of these Triassic Rift basins. The equatorial location and monsoonal climate of the Newark Rift basin during the Triassic provided the setting for orbital forcing fluctuations to effect climate, which in turn effected lake levels, and the associated sedimentary facies, within that basin. The Newark Basin Drilling Project, run by Lamont-Doherty Earth Observatory in 1991, drilled six cores throughout the Newark Basin to collect a continuous stratigraphic section of the Triassic rocks. Several shallow seismic profiles in the vicinity of the Titusville, Nursery Road, and Princeton coring sites were to be used to examine the lateral continuity of facies between the cores. However, a complex near-surface weathering zone generated from geophysical logs collected at these same core sites demonstrate that there is relatively high reflectivity in the subsurface at these locations. The synthetics suggest that if the near-surface problem is overcome, good seismic profiles can be collected. Cyclostratigraphy with the Newark Basin, consisting of Van Houten cycles of 21,000 years, the associated beat cycles of 100,000 and 400,000 years, and the obliquity cycle of 41,000 years are observed in spectral analyses of reflectivity series from the Titusville. Nursery Road, and Princeton geophysical logs. High reflectivity is correlated to the transition from the low velocity thick black shale sequences, representing the deepest-water facies, to the higher velocity shallow water/playa facies. The sedimentation rates with the Newark Basin, estimated by fixing the 413 ky cycle peaks of the reflectivity series, show variation between 0.5643 ft/ky and 0.9416 ft/ky during its 25 My history, but an overall average of 0.7316 ft/ky agrees with the rate of 0.7283 ft/ky used in this study and previously in the literature. back to bibliography

DOSECC, 1994, Newark basin coring project [Report by DOSECC for Continental Scientific Drilling on the mechanics of the project], DOSECC Continental Scientific Drilling Office, CSD Program at Texas A&M University, College Station, Texas, 200+ p.

A proposal was submitted in June of 1989 to the Continental Lithosphere Program of the National Science Foundation by Dennis V. Kent and Paul E. Olsen, principle investigators (PI). A continental drilling program was proposed to obtain a complete, detailed record of the evolution of a classical and logistically accessible continental rift, the early Mesozoic Newark basin. The proposal consisted of coring shallow holes designed to recover approximately 16,400 feet (5000 meters) of Late Triassic age sediments and igneous rocks. The objective was a very high resolution chronostratigraphy yielded from the physical stratigraphy of the sediments and especially the documented sedimentary cycles of climatic origin, combined with biostratigraphic, magnetostratigraphic, and chemostratigraphic control, to serve as a standard reference section for the Early Mesozoic Newark Supergroup and thus a framework for regional and global correlation essential to the development of models of continental rifting. back to bibliography

El Tabakh, M. E., 1994, Early rift-basin deposition; Triassic-Jurassic sedimentation and subsequent diagenesis in the Newark Basin, New Jersey. [Ph.D. Thesis] City College (CUNY), New York, NY, USA, 405 p.

The sedimentary characteristics of the Late Triassic sedimentary sections (7 km) of the Newark rift basin of eastern North America seen in the subsurface of New Jersey exhibit a great diversity of depositional environments, lithological associations, and authigenic mineral assemblages. The studied sedimentary section (Newark Supergroup) includes fluvial-alluvial deposits Stockton Formation), lacustrine depositional cycles (Lockatong Formation), and massive red mudstones and associated evaporites (Passaic Formation).

Within the sediments of the Newark Supergroup there is lithologic and geochemical evidence that indicates changes of the depositional system through time and that regional and later paleofluid movements have mobilized some components of the original lithologies. Depositional changes were mostly related to variations in the original paleoclimate and tectonic conditions that have effected the basin during its sedimentary evolution.

The Stockton Formation (1800 m) is the early rift basin sedimentary phase, consisting of conglomerates, sandstones and shaley mudstones that contain nodular carbonates (calcrete) arranged in repeated packages of upward fining sequences. The formation is characterized by a overall upsection decrease in grain size. Several distinct diagenetic features include early diagenetic cementation by calcite, displacive development of nodular calcite along root and burrow traces, and calcite replacement of some clays within the mudstone. Later diagenetic alternation includes albitzation of some calcite in calcrete and the transformation of illitic clays into 2M-illite (Muscovite). The late authigenic mineralogy resulted from circulation of hot basinal diagenetic fluids which altered and remobilized components of the original mineral assemblage, and apparently did not bring in a significant volume of new ions.

Lockatong Formation (1.1 km) includes organic-rich shales and carbonates. Isotopic data of the lacustrine carbonates indicate that the carbonates are largely primary in origin and that their original isotopic signatures have not been significantly modified by later diagenetic fluids. This is because the sedimentary porosity and permeability were reduced at an early stage of deposition, due to the synsedimentary alteration of clays to analcime which infilled the original porosity of the sediments.

Within the Passaic Formation (3,500 m) there is evidence of en upward progressive increase in the deposition of evaporites. Evaporites were formed displacively within the soft muds of shallow lakes and playas that occupied the rift-basin. Evaporite formation was probably due to progressive concentration of dissolved sulfates in the basin both due to an upward increase in aridity and an increase in basinal depositional area through time. During later diagenetic events (post Middle Jurassic to Modern), evaporites were exposed to extensive dissolution and remobilization that caused the formation of fibrous gypsum cements. back to bibilography

Fowell, S. J. 1993, Palynology of Triassic/Jurassic boundary sections from the Newark Supergroup of Eastern North America: Implications for catastrophic extinction scenarios [Ph. D. Thesis]: New York, New York, Columbia University, 133 p.

The synchroneity and significance of Late Triassic faunal extinctions have been hotly debated in recent years. Palynological data from the Triassic/Jurassic boundary of the Newark Supergroup, eastern United States, test catastrophic extinction theories and elucidate terminal Triassic events.

The palynologically defined Triassic/Jurassic boundary within the Newark Supergroup is broadly identified by a transition from palynofloras containing diverse Triassic species to Jurassic assemblages dominated by the genus Corollina. Intensive sampling of this transition interval in the Jacksonwald syncline of the Newark basin reveals a complex pattern of floral turnover that tightly constrains the position of the boundary. A 60% regional extinction of Triassic species coincides with a sharp increase in the percentage of trilete spores. Spore-dominated palynofloras are replaced upsection by Jurassic assemblages. Orbitally controlled sedimentary cycles allow temporal calibration of stratigraphic sections and limit the duration of the palynofloral turnover to 21ky.

Palynofloras immediately above mass-kill horizons are characteristically dominated by spores; this palynological evidence of catastrophe in the Newark Supergroup is strengthened by the brevity of the transition interval. Palynomorph assemblages above the last, diverse Triassic assemblages and below the spore spike are dominated by Corollina, but retain Triassic species in low numbers. Results from the Culpeper and Fundy basins demonstrate that these palynofloras are indicative of the latest Triassic. The regional extent and limited stratigraphic occurrence of these palynofloras is consistent with impact scenarios. However, since the spore spike has not yet been found outside the Jacksonwald syncline, and a search for shocked quarz is still underway, rapid climate change remains a viable driving mechanism for the sudden decline of Triassic species.

To clarify the interaction between Late Triassic floras and climates, samples were taken throughout 21ky cycles in the Newark and Richmond basins. Lack of palynomorphs in the shallow lacustrine facies of the Newark basin precludes detailed analysis of palynofloral composition throughout 21ky cycles. Preliminary results from the relatively humid Richmond basin suggest that the pollen/spore ratio responds to climatic changes on the order of 100ky, and that spores and bisaccate pollen are particularly sensitive to changes in precipitation/evaporation between successive 21ky cycles.back to bibliography

Goldberg, D., Reynolds, D., Williams, C., Witte, W. K., Olsen, P. E., and Kent, D. V., 1994, Well logging results from the Newark Rift Basin Coring Project. Scientific Drilling, 4 (4-6), pp. 267-279.

Wireline logs were aquired at seven sites in the Newark Rift basin using dipmeter, gamma ray, resistivity, velocity, porosity, density, magnetic susceptibility, temperature, and acoustic telaviewer tools. The logs indicte that the formations are clay rich and dip on average 9° N-NW. Densities are relatively constrant (2.6-2.8 g/cc) and copressional velocities vary from 4.2-5.5 km/s. Thin uranium-rich layers and basalt flows are clearly deliniated. The boreholes are mostly in-gauge, but deviated, and borehole temperature gradients vary between 15 to 26° C/km. These data are potentially useful as indicators of fluid flow and regional stress, lithologic cycles, and for core orientation in the Newark Rift basin. back to bibliography

ICG/CDS, 1992, The United States Continental Scientific Drilling Program: Fourth Annual Report to Congress in response to Public Law 100-441, the Continental Scientific Drilling and Exploration Act of 1988. Interagency Coordinating Group for Continental Scientific Drilling (ICG/CSD [Department of Energy, National Science Foundation, U.S. Geological Survey]), +38 p.

The Continental Scientific Drilling and Exploration Act of 1988, Public Law 100-441, requires the member agencies of the Interagency Coordinating Group for Continental Scientific Drilling (ICG/CDS) - the Department of Energy, the National Science Foundation, and the U.S. Geological Survey of the Department of the Interior - to submit an annual report to Congress on the United States Continental Scientific Drilling Program (U.S. CSDP). The submission of the report is rotated among these agencies. This, the Forth Annual Report, is submitted by the Secretary of the Department of the Interior to Report U.S. CSDP accomplishments during FY 1991, activities during FY 1992, and plans and funding requirements for FY 1993.

The U.S. CSDP is a program of coordinated continental scientific drilling activities of the ICG/CSD agencies that is consistent with the statutory authorities and missions of these agencies. The coordination is carried out by the ICG/CSD-member agency representatives.

The policy objectives and scientific goals of the U.S. CSDP are focused on an improved understanding of the Earth's continental crust. Scientific studies of the projects of this program are oriented toward, among other things, mechanisms controlling earthquakes, volcanic processes, hydrologic processes, and hydrocarbon and ore formation. Results from these studies yield economic, technological, and societal benefits through direct application of ongoing efforts elsewhere to solve major national problems dealing with the mitigation of hazardous effects of earthquakes and volcanic eruptions, isolation of radioactive and other hazardous wastes, adequate supplies of energy, water, and mineral resources, enhancement of U.S. industrial competitiveness in related technological areas, and expanded opportunities for training in science and engineering education.

To achieve these objectives and goals, the ICG/CSD agencies are pursuing a program of phased, systematic drilling, with development of appropriate drilling, sampling, logging, and downhole experimentation capabilities. Projects include those with post-drilling scientific studies for which drilling has been completed, those for which drilling is now underway, and those with pre-drilling site studies for which drilling is being considered. Further progress requires continuation of all three types. back to bibliography

Kent, D. V. and Olsen, P. E., 1996, Statistical Properties of an Astronomically Tuned Geomagnetic Polarity Time Scale for the Late Triassic. EOS, Supplement, v. 77, no. 46, p. F171.

We previously reported a high resolution geomagnetic polarity sequence for the Late Triassic-earliest Jurassic in a 4660 meter-thick composite section of mostly cyclic continental sediments from the Newark Basin. Of the 58 complete normal and reverse polarity magnetozones identified in the Late Triassic part of the section, relative age control for 40 polarity intervals is based on an astronomically-tuned climate stratigraphy (413 ky orbital eccentricity cycle) and on an extrapolation of sedimention rates for the older 18 polarity intervals. The entire polarity sequence spans 28 m.y., from ~202 to 230 Ma according to available radiometric dating.

We have resampled the boundaries of most of the magnetozones in the cyclic sedimentary facies to refine the magnetostratigraphy and to obtain estimates of polarity transition durations. The polarity interval lengths for either the entire sequence or the astronomically calibrated subset have a mean duration of about 0.5 m.y. and are closely approximated by an exponential distribution. Estimated values of the gamma index, k, are very close to unity which is compatible with an underlying stochastic reversal process such as the Poisson that has often been suggested for the well known history of Cenozoic polarity reversals. The 42 sampled profiles representing 35 different polarity reversals give transition durations ranging from 1.9 to 20 Ky with a mean of 8.0±14.4 Ky, comparable to duration estimates of recent polarity transitions. It would appear from these statistical properties that the behaviour of the geomagnetic field in the Late Triassic was not very different than in the Cenozoic, which conjointly would suggest that the Late Triassic geomagnetic polarity time scale is reasonably complete. back to bibliography

Kent, D. V., Olsen, P. E., and Witte, W. K., 1995, Late Triassic-Early Jurassic geomagnetic polarity sequence and paleolatitudes from drill cores in the Newark rift basin (Eastern North America). Journal of Geophysical Research, v. 100, p. 14965-14998.

Paleomagnetic study of about 2400 samples from nearly 7 km of core recovered at seven drill sites in the Newark continental rift basin of eastern North America provides a detailed history of geomagnetic reversals and paleolatitudinal motion for about 30 m.y. of the Late Triassic and earliest Jurassic (Carnian to Hettangian). Northward drift of only about 7° is recorded in the continental sediments and minor interbedded basaltic lavas in the basin, from 2.5° to 6.5° north paleolatitude in the Carnian and from 6.5° to 9.5° north paleolatitude over the Norian-"Rhaetian" and the early Hettangian. A total of 59 polarity intervals, ranging from about 4 m to over 300 m in thickness, have been delineated in a composite stratigraphic section of 4660 m. The lateral continuity and consistent relationship of lithological lake level cycles and magnetozones in the stratigraphically overlapping sections of the drill cores demonstrate their validity as time markers. A geomagnetic polarity timescale was constructed by scaling the composite section assuming that lithostratigraphic members in the predominant lacustrine facies represent the 413-kyr orbital periodicity of Milankovitch climate change and by extrapolating a sedimentation rate for the fluvial facies in the lower part of the section; a 202 Ma age for the palynological Triassic/Jurassic boundary was used to anchor the chronology based on published concordant radiometric dates linked to the earliest Jurassic igneous extrusive zone. Geomagnetic polarity intervals range from about 0.03 to 2 m.y., have a mean duration of about 0.5 m.y., and show no significant polarity bias. The cyclostratigraphically calibrated record provides a reference section for the history of Late Triassic-earliest Jurassic geomagnetic reversals. Correlations are attempted with available magnetostratigraphies from nonmarine sediments from the Chinle Group of the southwestern United States and marine limestones from Turkey. back to bibliography

Olsen, P. E., Kent, D V., Cornet, B., Witte, W. K., and Schlische, R. W., 1996, High-resolution stratigraphy of the Newark rift basin (Early Mesozoic, Eastern North America): Geological Society of America, v. 108, no. 1, p 40-77.

Virtually the entire Late Triassic and earliest Jurassic age section of the early Mesozoic 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 comprise 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 4,660 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 magnetostratigraphic correlations between core overlap zones and outcrops demonstrates that the individual sedimentary cycles can be traced essentially basin wide. The agreement between the cyclostratigraphy and magnetostratigraphy shows both the cycles and the polarity boundaries to be isochronous horizons. Detailed analysis of the Newark basin shows that high-resolution cyclostratigraphy 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.back to bibliography

Olsen, P. E. and Kent, D. V., 1996, Precession Cycle Frequency Doubling at the Equator of Triassic Pangea. EOS, Supplement, v. 77, no. 46, p. F301.

Crowley et al. (1992, Science, 255: 705) propose that a roughly 10 Ky cycle, driven by climatic precession, should be present in long-term variations in precipitation over the continents at the equator. They point out that this frequency doubling of the precession cycle should amplify the effects of the roughly 100 Ky eccentricity cycle. Unfortunately, there are no Quaternary equatorial continental records that can be used to test this hypothesis, although several marine records have reported 10 Ky cyclicity. However, a Triassic venue can fill this, presumably temporary, continental desideratum because: 1) there are very long (>5 my), readily accessible rift basin lacustrine records spanning over 30 of paleolatitude and 30 my (~200-230 Ma); 2) these records can be correlated at very high levels of resolution because of recent advances in the Triassic magnetic polarity time scale; and 3) because of the extreme continentality of Pangean climate these lacustrine records should be extremely sensitive to insolation variations driven by celestial mechanics.

Here we report on a direct comparison of two contemporaneous, paleomagnetically correlated, cyclical lacustrine records from the Triassic Pangean tropics, both having formed in very large but isolated rift lakes. One is from the Dan River basin of VA and NC and was located at the paleoequator during the deposition of most of its preserved record. The other is from the Newark basin of NY, NJ, and PA and was deposited at about 3 N latitude during the interval represented in the Dan River section. The Newark basin record also spans the interval later in the Triassic during which the basin drifted to about 10 N. Paleomagnetic polarity correlation allows both sections to be placed in a common time scale. The direct comparison, using Fourier analysis, shows that 10 Ky cyclicity was dominant over 20 Ky in the Dan River section, while 20 Ky cycles dominated the Newark basin record over the same time interval. Strong cycles with prominent periods of about 100 and 400 Ky are present in both records, but there is little evidence of the 41 Ky cycle. The younger portion of the Newark basin record shows even less influence of the 10 Ky cycle. We attribute this 10 ky cyclicity at the Pangean equator to a doubling of the frequency of the cycle of climate precession, and infer that the 10 Ky cyclicity is a consequence of the two times per precession cycle that the solstice occurs at perihelion at the equator. It was during those times that convergence-driven precipitation was most intense and the rift lakes were deepest. We postulate that such a pattern has always been an attribute of continental equatorial climate.back to bibliography

Olsen, P. E. and Kent, D. V., 1996, Milankovitch climate forcing in the tropics of Pangea during the Late Triassic. Palaeogeography, Palaeoclimatology, and Palaeoecology, v. 122, p. 1-26.

During the Triassic, the Newark rift basin of Eastern North America was in the interior of tropical (3-7°N) Pangaea. Strikingly cyclical lacustrine rocks comprise most of the 6770 m of continuous core recovered from this basin by the Newark Basin Coring Project Six of the seven drill cores (each from 800-1300 m long) from this project are used here to construct a composite lake-level curve that provides a much needed record of long term variations in tropical climate. The main proxy of lake level and hence climate used to construct this lake level curve is a classification of water-depth related sedimentary structures and fabrics called depth ranks. We then use Fourier frequency analysis (both FFT and multitaper methods) and joint time-frequency approaches to resolve the periodic properties of the cyclicity and the secular drift in those properties. A consistent hierarchy in frequencies of the lake level cycle is present throughout the Triassic and earliest Jurassic portions of the cores. Calibration of the sediment accumulation rate by a variety of methods shows that these thickness periodicities are consistent with an origin in changes in precipitation governed by celestial mechanics. In specific, the full range of precession-related periods of lake level change are present, including the two peaks of the ~20,000 year cycle of climatic precession, the two peaks of the ~100,000 year eccentricity cycle, the single peak of the 412,900 year eccentricity cycle, and the ~2,000,000 year eccentricity cycle. There is good correspondence in the details of the joint-time frequency properties of cores and the astronomical predictions as well. In an ice-free world, the tropical climate of Pangaea responded strongly to astronomical forcing. Such precession-dominated forcing is still and probably always has been a prominent feature of tropical climate.back to bibliography

Olsen, P. E., and Kent, D., 1990, Continental Coring of the Newark Rift: EOS, Transactions of the American Geophysical Union, v. 71, p. 385, 394.

The entire Late Triassic record of the Newark continetal rift of New Jersey, New York, and Pennsylvania will be drilled to recover about 7000 m of continous core under the National Science Foundation's Continental Lithosphere Program. Unlike the relatively well-known postrift sedimentary succession of continental margins, there is hardly any continental rift sequence known in the deatil necessary for quantitative tectonic or stratigraphic models. The Newark basin is one of the most acessible and most studied rifts in the world. While much has been learned over the 150 years of study by piecing together the record from disconinous outcrops ..., inevitable uncertainties in correlation and facies relationships have hampered the development of a comprehensive tectonic and stratigraphic history. ... [no abstract supplied with the original paper]. back to bibliography

Parnell, J. and Monson, B., 1995, Paragenesis of hydrocarbon, metalliferous and other fluids in Newark Group basins, Eastern U.S.A. Institution of Mining and Metallurgy, Transactions, Section B: Applied Earth Science ; Vol. 104, August, p. 136-144.

Bitumen shows occur in the Newark, Hartford, and Deerfield Basins, eastern U.S.A., in reservoir sandstones, veinlets in the vicinity of hydrocarbon source rocks, veins through lava beds and in sulfide-mineralized veins. The bitumen shows occur late in the diagenetic history of the sandstones occupying dissolution porosity. The parent hydrocarbons entered the sandstones from crosscutting fractures. In sulfide-mineralized veins bitumens are closely associated with, but predate the sulfides. The role of organic matter was probably in enhancing metal reduction by creating a low-Eh environment rather than in metal transport. In several cases bitumens contain euhedral quartz crystals that were precipitated coevally with the bitumen, indicating a significant aqueous component to the hydrocarbon fluid. Inclusions in the quartz crystals variably contain hydrocarbon or aqueous fluids. Primary inclusions contain aqueous fluid, which is consistent with the sequence of bitumen precipitation before sulfide precipitation in veins. Homogenization temperatures for aqueous solutions in south-central Connecticut are in the range 110-120° C.

Bitumen-bearing carbonate veinlets in the Newark Basin occur in carbonate-rich sequences. Study of the veinlets under cathodoluminescence shows that there were two or more distinct episodes of carbonate veining. Sulphides were deposited in the first carbonate phase and bitumens were deposited in the second. Albite was deposited coevally with the bitumen, providing further evidence of an aqueous component to the hydrocarbon fluid.back to bibliography

Reynolds, D. J., 1993, Sedimentary basin evolution: tectonic and climatic interaction [Ph.D. thesis]: New York, New York, Columbia University, 215 p.

Tectonic and climatic events are recorded in the strata of sedimentary basins. However, the stratigraphic record is complex and it is often difficult to distinguish and separate events which can be attributed to a given process or event. My work has been directed toward developing and refining methods by which these events can be recognized. This is accomplished by use of forward and inverse models, as well as new data sets. Because this is a broad topic, I have focused on only a few problems which have been selected for their potential to 1) illustrate common misapplications of currently employed models and 2) provide new ways of distinguishing tectonic and climatic events.

Forward models demonstrate the important role that isostasy and compaction play in sequence stratigraphic geometry. Inverse models used to reconstruct sequences of the Baltimore Canyon provide insights on the significance of the depositional shelf break. The Miocene shelf breaks, when reconstructed, lie at paleowater depths of ~170 m. Thus, models which equate shoreline with the depositional shelf break in this region are flawed and attempts to reconstruct eustatic sea level fluctuations on the basis of clinoform geometry must take this into account.

Seismic and well data from the Newark rift basin document syndepositional growth of basin structures. Well data show both regular variations in sedimentary cycle thickness through time, which are interpreted to represent changing climatic conditions, and irregular cycle thickness changes, which are interpreted to be of tectonic origin. Decompaction calculations based on data from coreholes yield estimates for accumulation rates of ~0.5 mm/yr. A full suite of Milankovitch cycles are shown to be present in sonic log data from the basin, with the 400 ky cycle resolvable in seismic reflection data. This provides a chronostratigraphic framework for interpreting seismic data within the basin.

Interpretation of newly released seismic reflection data from the Lake Superior basin documents inversion structures. These data indicate that application of rift basin segmentation models, such as those proposed for East Africa, are not applicable to this basin.back to bibliography

Smoot, J. P. and Olsen, P. E., 1994, Climatic cycles as sedimentary controls of rift basin lacustrine deposits in the early Mesozoic Newark basin based on continuous core. in Lomando, A. J. and Harris, M., Lacustrine Depositional Systems, SEPM Core Workshop Notes, v. 19, p. 201-237.

The Newark Basin Coring Project (NBCP) has recovered over 6730 m of continuous core from 7 coring sites. Core spanning the 4800 m of Lockatong and Passaic formations are characterized by cyclic lacustrine mudstone and shal;e, which reflect rise and fall of lake level in response to climatic flustuations at intervals of 20,000 years and larger patterns of 100,000- and 400,000-year intervals. Sedimentary structures in the mudstone include:

1. Organic-rich laminites with thin, flat, continuous lamination; thick lamination with diffuse or irregular boundaries; silty or sandy laminae; or crystal-rich lamination.
2. Mudcracked, thin-bedded mudstone with lenticular sandstone layers; graded sandstone layers; mudstone layers with sharp contacts; muddy siltstone curls; or crystal-rich layers.
3. Massive mudstones with angular breccia fabic; vesicular fabric; rounded breccia fabric; root-disrupted fabric; or crystal-rich fabrics.

These structures define five types of cycles:

1. Cycles dominated by thick, organic-rich laminites deposited in deep lakes and roundes breccias, relecting deflated, salt encrusted mudflats.
2. Cycles similar to the previous, but with more thin-bedded mudstone and massive mudstone with upward-fining crystal sequences reflecting saline mudflats.
3. Cycles with mudcracked thin beds grading up to brecciated mudstone, then vesicular fabric reflecting shallow lakes drying up to dry playa mudflats.
4. Cycles similar to the previous, but with more organic-rich laminites or thin beds and root-distrupted mudstone at top, indicating wetter conditions and vetitation growth before lake trangressions.
5. Cycles dominated by root-disrupted mudstone and thin, organic-poor laminites or thin beds reflecting thick soil superiposed on shallow lake deposits.

The abundance of each cycle type changes through the stratigraphic section, reflecting the change from arid conitions in a narrow basin upward to semi-arid to subhumid conditions in a broad basin. The use of climatic patterns and tectonic settings can provide important information towards modeling source and reservior rocks in rift basin lacustrine settings. back to bibliography

van Veen, Paul M., Fowell, S. J., Olsen, P. E., 1995, Time calibration of Triassic/Jurassic microfloral turnover, eastern North America [discussion and reply]. Tectonophysics, v. 245, no. 1-2, p. 93-99.

Van Veen argues that the Newark palynological data suggests a several million year hiatus between latest Triassic and earliest Jurassic horizons in the Newark basin because of the lack of a "Rhaetian" pollen zone that is present in Europe. Fowell and Olsen, however, state that there is no physical geological evidence for such a hiatus, and much against it, and suggest that the palynological differences are due to the large geographic and climatic separation of the two areas. [no abstract with paper] back to bibliography

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