The K–T boundary in Oman: identified using magnetic susceptibility field measurements with geochemical confirmation

Ellwood, Brooks B.; MacDonald, W. D.; Wheeler, Christopher; Benoist, Stephen L.

doi:10.1016/s0012-821x(02)01124-x

Cited by 62 publications

(37 citation statements)

References 25 publications

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“…Other smaller late Maastrichtian craters have been recently reported from the Ukraine (Boltysh crater, Kelley and Gurov 2002) and from the North Sea (Silverpit crater; Stewart and Allen 2002). In addition, late Maastrichtian PGE anomalies have been reported from Oman (Ellwood et al 2003). A possible early Danian (P. eugubina zone, approx.…”

Section: The K/t Boundary At Yaxcopoil-1mentioning

confidence: 98%

Yaxcopoil-1 and the Chicxulub impact

Stinnesbeck

Keller

Adatte

et al. 2004

Int J Earth Sci (Geol Rundsch)

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CSDP core Yaxcopoil-1 was drilled to a depth of 1,511 m within the Chicxulub crater. An organic-rich marly limestone near the base of the hole (1,495 to 1,452 m) was deposited in an open marine shelf environment during the latest Cenomanian (uppermost Rotalipora cushmani zone). The overlying sequence of limestones, dolomites and anhydrites (1,495 to 894 m) indicates deposition in various carbonate platform environments (e.g., sabkhas, lagoons). A 100-m-thick suevite breccia (894-794 m) identifies the Chicxulub impact event. Above the suevite breccia is a dolomitic limestone with planktic foraminiferal assemblages indicative of Plummerita hantkeninoides zone CF1, which spans the last 300 ky of the Maastrichtian. An erosional surface 50 cm above the breccia/dolomite contact marks the K/T boundary and a hiatus. Limestones above this contact contain the first Tertiary planktic foraminifera indicative of an upper P. eugubina zone P1a(2) age. Another hiatus 7 cm upsection separates zone P1a(2) and hemipelagic limestones of planktic foraminiferal Zone P1c. Planktic foraminiferal assemblages of Zone Plc to P3b age are present from a depth of 794.04 up to 775 m. The Cretaceous carbonate sequence appears to be autochthonous, with a stratigraphic sequence comparable to late Cretaceous sediments known from outside the Chicxulub crater in northern and southern Yucatan, including the late Cenomanian organic-rich marly limestone. There is no evidence that these sediments represent crater infill due to megablocks sliding into the crater, such as major disruption of sediments, chaotic changes in lithology, overturned or deep dipping megablocks, major mechanical fragmentation, shock or thermal alteration, or ductile deformation. Breccia units that are intercalated in the carbonate platform sequence are intraformational in origin (e.g., dissolution of evaporites) and dykes are rare. Major disturbances of strata by the impact therefore appear to have been confined to within less than 60 km from the proposed impact center. Yaxcopoil-1 may be located outside the collapsed transient crater cavity, either on the upper end of an elevated and tilted horst of the terrace zone, or even outside the annular crater cavity. The Chicxulub site thus records a large impact that predates the K/T boundary impact and mass extinction.

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Section: The K/t Boundary At Yaxcopoil-1mentioning

confidence: 98%

Yaxcopoil-1 and the Chicxulub impact

Stinnesbeck

Keller

Adatte

et al. 2004

Int J Earth Sci (Geol Rundsch)

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“…The higher iron content represented by high MS magnitudes resulted from increased rates of weathering and delivery of paramagnetic minerals associated with a net fall in sea level [29]- [32]. The MS is known as a viable tool for correlating geological sequences [31]- [33].…”

Section: Magnetic Susceptibilitymentioning

confidence: 99%

“…By doing this, positive MS values (to the right of zero) represent magnitudes greater than the average and negative values (to the left of zero) represent magnitudes less than the average. It has been argued that the effects of sea level rise and fall, caused by either climate or tectonics or both, had the greatest effect on the supply of iron (Fe) to the depositional environments [32] [33].…”

Section: Magnetic Susceptibilitymentioning

confidence: 99%

Sequence Stratigraphy and Sea Level Fluctuations of the Ab-Deraz Formation, Based on Palynological Evidence and Magnetic Susceptibility Method “Kopet-Dagh Sedimentary Basin, Northeastern Iran”

yousefimoghadam¹,

Hoseininezhad²,

Allameh³

2015

OJG

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Ab-deraz Formation is one of the Lithostratigraphic units of upper cretaceous (Middle TouronianSantonian) in Kopet-Dagh sedimentary basin, located in northeastern Iran. The aims of this study are separating sequence units and determining sea level Fluctuation by using palynological factors and comparison via magnetic susceptibility which is used for the first time in Ab-deraz Formation. Assuming the average MS magnitude as the proxy for mean sea level changes, positive Magnetic Susceptibility (MS) values were considered to present sea level falls and negative values for sea level rises. Based on these data a curve showing water level fluctuations throughout the stratigraphic column was prepared which shows a general trend of regression from base to the top of the formation. To test accuracy of this method, magnetic susceptibility results were compared with those gained from palynology and palynofacies studies. Based on the changes in palynological factors (the terrestrial/marine particles ratio, C/PPC ratio, diversity and abundance of dinoflagellate), palynofacies, for separate sequences, three sequences of the third type with four sequence boundaries, (3 boundaries of the type II and one boundary of the type I) were differentiated, confirming the results gained from magnetic susceptibility method.

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“…Let us discuss the important problem of the global synchronism of the Mz-Kz biostratigraphic boundary and, hence, that of the κ-peaks, which is emphasized by many researchers [Ellwood et al, 2003]. First, we will examine the positions of the Mz-Kz boundary and κ-peaks inside the C29r chron.…”

Section: Magnetic Susceptibility In the Oceanic Sediments In The Vicimentioning

confidence: 99%

“…which expressed in the anomalous contents in the sediments of cosmic-origin platinoid metals, in particular, of iridium, and in the presence of shock-metamorphosed quartz and tectites in the sediments, (d) some enrichment of oceanic and marine sediments in magnetic minerals, which is expressed in the fairly narrow anomalous peak of magnetic susceptibility at or in the vicinity of this boundary [Alvares et al, 1990;Baulus et al, 2000;Courtillot et al, 2003;Ellwood et al, 2003;Ernst and Buchan, 2003;Grachev, 2000;Montanari et al, 1998;Smith et al, 1982;Veimarn et al, 1998], and (e) the intensification of differential plate movements which expressed in the highest dispersion of the plate movement rates against the background of the growing average velocity of the continental plate movement (Figure 1c) [Jurdy et al, 1995;Pechersky, 1998]. The synchronism or the nearly synchronous occurrence of these events at the Earth surface obviously suggest some common mechanism responsible for them.…”

Section: Introductionmentioning

confidence: 99%

The Mesozoic-Cenozoic boundary: Paleomagnetic characteristic

Pechersky¹,

Garbuzenko²

2005

Russ. J. Earth Sci.

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Abstract. The purpose of this paper is to consider the behavior of the geomagnetic field in the vicinity of the Mesozoic-Cenozoic (Mz-Kz) boundary, in particular, of the paleointensity and polarity of the field, the frequency of geomagnetic polarity reversals, the total magnitude of the field direction variations, and the behavior of the magnetic susceptibility of oceanic sediments in the vicinity of the Mz-Kz boundary. As to these paleomagnetic events, worthy of mention is the change in the variation conditions at the Mesozoic-Cenozoic boundary. It is global growth of the average variation magnitude from 8• -8.5• in the Late Cretaceous to 11.5• in the Early Cenozoic. The global character of this event suggests a general change in the generation of the geomagnetic field direction variations in the vicinity of the Mz-Kz boundary. A change in the Earth core conditions, causing the reversals of the geomagnetic field, began at ∼80 Ma, that is, notably earlier than the Mz-Kz boundary, and, hence, was not associated directly with this boundary, nor with the generation of variations in the geomagnetic field direction. Some local changes in the variations of the magnetic field direction were associated with the formation of plumes near the core-mantle boundary, yet, the plumes have originated 20-40 million years prior to the Mz-Kz boundary. As follows from the examination of sequences of oceanic sediments (DSDP and ODP data), the Mz-Kz boundary is often, but not necessarily, marked by a peak of magnetic susceptibility (κ-peak), i.e. that is not a characteristic feature of the Mz-Kz boundary. The accumulation of magnetic materials in the sediments lasted from a few dozens of thousand years (more common estimates) to hundreds of thousand years. And, where this interval is observed, it does include the Mz-Kz biostratigraphic boundary, except for very rare cases. The Mz-Kz biostratigraphic boundary is always restricted to the C29r chron, but its position varies as a function of its paleolatitude, amounting to about 0.7 Myr. The highest κ-peak values are close to the epicenters of active plumes, but high κ-peaks have been found far from the plumes.

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The K–T boundary in Oman: identified using magnetic susceptibility field measurements with geochemical confirmation

Cited by 62 publications

References 25 publications

Yaxcopoil-1 and the Chicxulub impact

Yaxcopoil-1 and the Chicxulub impact

Sequence Stratigraphy and Sea Level Fluctuations of the Ab-Deraz Formation, Based on Palynological Evidence and Magnetic Susceptibility Method “Kopet-Dagh Sedimentary Basin, Northeastern Iran”

The Mesozoic-Cenozoic boundary: Paleomagnetic characteristic

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