Time calibration of Triassic/Jurassic microfloral turnover, eastern North America

Fowell, Sarah J.; Olsen, Paul E.

doi:10.1016/0040-1951(93)90359-r

Cited by 102 publications

(92 citation statements)

References 18 publications

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“…1999). An increase in abundance of the thermophilic pollen Classopollis (Corollina) is noted in Europe and eastern North America for this interval (Fowell & Olsen 1993;Hesselbo et al . 2002).…”

Section: Rapid Warming During Triassic-jurassic Boundary Timementioning

confidence: 99%

Evidence for rapid climate change in the Mesozoic–Palaeogene greenhouse world

Jenkyns

2003

Philosophical Transactions of the Royal Society of London. Seri

444

308

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The best-documented example of rapid climate change that characterized the socalled 'greenhouse world' took place at the time of the Palaeocene-Eocene boundary: introduction of isotopically light carbon into the ocean-atmosphere system, accompanied by global warming of 5-8• C across a range of latitudes, took place over a few thousand years. Dissociation, release and oxidation of gas hydrates from continental-margin sites and the consequent rapid global warming from the input of greenhouses gases are generally credited with causing the abrupt negative excursions in carbon-and oxygen-isotope ratios. The isotopic anomalies, as recorded in foraminifera, propagated downwards from the shallowest levels of the ocean, implying that considerable quantities of methane survived upward transit through the water column to oxidize in the atmosphere. In the Mesozoic Era, a number of similar events have been recognized, of which those at the Triassic-Jurassic boundary, in the early Toarcian (Jurassic) and in the early Aptian (Cretaceous) currently carry the best documentation for dramatic rises in temperature. In these three examples, and in other less well-documented cases, the lack of a definitive time-scale for the intervals in question hinders calculation of the rate of environmental change. However, comparison with the Palaeocene-Eocene thermal maximum (PETM) suggests that these older examples could have been similarly rapid. In both the early Toarcian and early Aptian cases, the negative carbon-isotope excursion precedes global excess carbon burial across a range of marine environments, a phenomenon that defines these intervals as oceanic anoxic events (OAEs). Osmium-isotope ratios ( 187 Os/ 188 Os) for both the early Toarcian OAE and the PETM show an excursion to more radiogenic values, demonstrating an increase in weathering and erosion of continental crust consonant with elevated temperatures. The more highly buffered strontium-isotope system ( 87 Sr/ 86 Sr) also shows relatively more radiogenic signatures during the early Toarcian OAE, but the early Aptian and Cenomanian-Turonian OAEs show the reverse effect, implying that increased rates of sea-floor spreading and hydrothermal activity dominated over continental weathering in governing sea-water chemistry. The Cretaceous climatic optimum (late Cenomanian to mid Turonian) also shows evidence for abrupt cooling episodes characterized by episodic invasion of boreal faunas into temperate and subtropical regions and changes in terrestrial vegetation; drawdown of CO 2 related to massive marine carbon burial (OAE) may be implicated here. The absence of a pronounced negative carbon-isotope excursion preceding the One contribution of 14 to a Discussion Meeting 'Abrupt climate change: evidence, mechanisms and implications'.

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Section: Rapid Warming During Triassic-jurassic Boundary Timementioning

confidence: 99%

Evidence for rapid climate change in the Mesozoic–Palaeogene greenhouse world

Jenkyns

2003

Philosophical Transactions of the Royal Society of London. Seri

444

308

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“…She distinguished a Rhaetian Assemblage (Assemblage V) and a Hettangian Assemblage (Assemblage VI). Fowell & Olsen (1993) worked on Triassic/Jurassic boundary sections of the Newark Basin (Eastern North America), while Ashraf et al (1999) studied the Rhaetian Haojiagou Formation and the Liassic Badaowan Formation of the Chinese Junggar Basin. Figure 7 shows the stratigraphical occurrence of the most important palynomorphs in the Furkaska section in comparison with the previous works mentioned above.…”

Section: Palynomorph Assemblagementioning

confidence: 99%

“…Palynological studies of the Triassic/Jurassic boundary with special focus on the extinction event are still rare. Fowell & Olsen (1993) describe a sudden floral turnover and a strong decrease in pollen and spore diversity coevally with an Iridium anomaly in terrestrial sediments of the Newark Supergroup (Newark Basin, USA). In other paleogeographical settings, indicators for a microfloral mass extinction are absent.…”

Section: Introductionmentioning

confidence: 99%

Climate change at the Triassic/Jurassic boundary: palynological evidence from the Furkaska section (Tatra Mountains, Slovakia)

Ruckwied¹,

Götz²

2009

Geologica Carpathica

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Abstract:The palynology of the Triassic/Jurassic boundary interval of the Furkaska section (Tatra Mts, Slovakia) was studied with respect to a major climatic change during that period. The palynofacies is dominated by terrestrial particles, indicating a shallow marine depositional environment. The palynomorphs are fairly well-preserved and the assemblage shows characteristic changes within the Triassic/Jurassic boundary interval: the lower part of the section is characterized by high abundance of Ricciisporites tuberculatus. The sudden increase in abundance of trilete spores, the decrease in the abundance of Ovalipollis spp., the last appearance of Alisporites minimus and Corollina spp., and the first appearance of Concavisporites rhaetoliassicus, Cyatidites australis, Callialasporites dampieri, Pinuspollenites minimus, Platysaccus spp. and Zebrasporites fibmriatus are striking features for a subdivision of two palynomorph assemblages. The detected spore shift is interpreted to display a sudden increase in humidity most probably caused by the volcanic activity of the Central Atlantic Magmatic Province (CAMP) associated with the onset of rifting of Pangaea during early Mesozoic times.

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“…The TriassicIJurassic boundary is constrained by palynology t o lie within the Exeter Member, correlated t o be about 2 0 m below the contact with the Orange Mountain Basalt in the NBCP section [Olsen et al, 1990;Fowell and Olsen, 1993;Fowell et al, 1994;Olsen et al, 19951. There is no physical evidence of an unconformity associated with the TriassicIJurassic boundary interval.…”

Section: Geomagnetic Polarity Timescalementioning

confidence: 99%

“…This palynofloral change may approximate the level of the NorianlRhaetian boundary, although criteria for recognition of the -RhaetianW are very uncertain te.g., Tozer, 19931. The TriassiclJurassic boundary is placed within the Exeter Member in the uppermost Passaic FormationI 2 0 m below the contact with the Jacksonwald Basalt that is correlative t o the Orange Mountain Basaltl based on the well-defined transition from the Upper Balls Bluff-Upper Passaic palynofloral zone t o the Corollina meyeriana palynofloral zone [Fowell and Olsen, 1993;Fowell et al, 19941. A spike in the sporelpollen ratio is found t o be coincident with a regional extinction of more than half of the palynoflora at the Triassic1Jurassic boundary which is also closely associated with terrestrial vertebrate extinctions [Olsen et al, 1990;Silvestri and Szajna, 19931.…”

Section: Geological Settingmentioning

confidence: 99%

Late Triassic‐earliest Jurassic geomagnetic polarity sequence and paleolatitudes from drill cores in the Newark rift basin, eastern North America

Kent¹,

Olsen²,

Witte³

1995

J. Geophys. Res.

164

189

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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.

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Time calibration of Triassic/Jurassic microfloral turnover, eastern North America

Cited by 102 publications

References 18 publications

Evidence for rapid climate change in the Mesozoic–Palaeogene greenhouse world

Evidence for rapid climate change in the Mesozoic–Palaeogene greenhouse world

Climate change at the Triassic/Jurassic boundary: palynological evidence from the Furkaska section (Tatra Mountains, Slovakia)

Late Triassic‐earliest Jurassic geomagnetic polarity sequence and paleolatitudes from drill cores in the Newark rift basin, eastern North America

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