10 results on '"Bralower, Timothy J."'
Search Results
2. A transient rise in tropical sea surface temperature during the Paleocene-Eocene Thermal Maximum
- Author
-
Zachos, James C., Wara, Michael W., Bohaty, Steven, Delaney, Margaret L., Petrizzo, Maria Rose, Brill, Amanda, Bralower, Timothy J., and Premoli-Silva, Isabella
- Subjects
Ocean temperature -- History -- Research -- Measurement -- Environmental aspects ,Science and technology ,Measurement ,Research ,History ,Environmental aspects - Abstract
The Paleocene-Eocene Thermal Maximum (PETM) has been attributed to a rapid rise in greenhouse gas levels. If so, warming should have occurred at all latitudes, although amplified toward the poles, Existing records reveal an increase in high-latitude sea surface temperatures (SSTs) (8° to 10°C) and in bottom water temperatures (4° to 5°C. To date, however, the character of the tropical SST response during this event remains unconstrained. Here we address this deficiency by using paired oxygen isotope and minor element (magnesium/calcium) ratios of planktonic foraminifera from a tropical Pacific core to estimate changes in SST. Using mixed-layer foraminifera, we found that the combined proxies imply a 4° to 5°C rise in Pacific SST during the PETM. These results would necessitate a rise in atmospheric pC[O.sub.2] to levels three to four times as high as those estimated for the late Paleocene., The Paleocene-Eocene Thermal Maximum [55 million years ago (Ma)] was accompanied by a number of environmental perturbations, including mass extinction of benthic foraminifera (1), widespread appearance and proliferation of exotic [...]
- Published
- 2003
3. On impact and volcanism across the Cretaceous-Paleogene boundary.
- Author
-
Hull, Pincelli M., Bornemann, André, Penman, Donald E., Henehan, Michael J., Norris, Richard D., Wilson, Paul A., Blum, Peter, Alegret, Laia, Batenburg, Sietske J., Bown, Paul R., Bralower, Timothy J., Cournede, Cecile, Deutsch, Alexander, Donner, Barbara, Friedrich, Oliver, Jehle, Sofie, Kim, Hojung, Kroon, Dick, Lippert, Peter C., and Loroch, Dominik
- Published
- 2020
- Full Text
- View/download PDF
4. Response: Cretaceous Extinctions
- Author
-
Peter Schulte, Laia Alegret, Ignacio Arenillas, Jose Arz, Peggy Barton, Brown, Paul R., Bralower, Timothy J., Gail Christeson, Philippe Claeys, Charles Cockell, Gareth Collins, Alex Deutsch, Tamara Goldin, Kazuhisa Goto, Manuel Grajales-Nishimura, J., Grieve, Richard A. F., Gulick, Sean P., Kirk Johnson, Wolfgang Kiessling, Christian Koeberl, David Kring, Kenneth Macleod, Takafumi Matsui, Jay Melosh, Alessandro Montanari, Joanna Morgan, Neal, Clive R., Nichols, Douglas J., Richard Norris, Elisabetta Pierazzo, Greg Ravizza, Mario Rebolledo-Vieyra, Wolf Uwe Reimold, Robin, E., Tobias Salge, Robert Speijer, Arthur Sweet, Jaime Urrutia-Fugugauchi, Vivi Vajda, Michael Whalen, Willumssen, Pi S., Chemistry, Isotope Geology and Evolution of Paleo-Environmnents, Geology, Analytical, Environmental & Geo-Chemistry, and Earth System Sciences
- Subjects
KT boundary ,Impact ,crater ,Asteroid or comet ,mass extinction ,dinosaurs - Abstract
THE LETTERS BY ARCHIBALD ET AL., KELLER ET al., and Courtillot and Fluteau question our conclusion that the Cretaceous-Paleogene mass extinction was caused by the asteroid impact at Chicxulub. All three Letters stress that Deccan flood basalt volcanism played a major role in the extinction. Keller et al. and Archibald et al. also mention that climate change was a factor, and Archibald et al. We disagree with the hypothesis that vol- canic activity can explain the extinction.
- Published
- 2010
5. Probing the hydrothermal system of the Chicxulub impact crater.
- Author
-
Kring, David A., Tikoo, Sonia M., Schmieder, Martin, Riller, Ulrich, Rebolledo-Vieyra, Mario, Simpson, Sarah L., Osinski, Gordon R., Gattacceca, Jérôme, Wittmann, Axel, Verhagen, Christina M., Cockell, Charles S., Coolen, Marco J. L., Longstaffe, Fred J., Gulick, Sean P. S., Morgan, Joanna V., Bralower, Timothy J., Chenot, Elise, Christeson, Gail L., Claeys, Philippe, and Ferrière, Ludovic
- Subjects
- *
IMPACT craters , *EARTH sciences , *SUBMARINE geology , *SULFIDE minerals , *LUNAR craters , *SILICATE minerals , *LIFE sciences , *GEOLOGICAL surveys - Abstract
The article informs about Probing the hydrothermal system of the Chicxulub peak-ring crater and multiring basin. Topics discusserd include information on International Ocean Discovery Program (IODP) and International Continental Scientific Drilling Program (ICDP) Expedition; and chemical and mineral alteration in the Chicxulub crater was previously detected within a few centimeter-size rock fragments from a petroleum exploration borehole.
- Published
- 2020
- Full Text
- View/download PDF
6. The Chicxulub Asteroid Impact and Mass Extinction at the Cretaceous-Paleogene Boundary.
- Author
-
Schulte, Peter, Alegret, Laia, Arenillas, Ignado, Arz, José A., Barton, Penny J., Bown, Paul R., Bralower, Timothy J., Christeson, Gail L., Claeys, Philippe, Cockell, Charles S., Collins, Gareth S., Deutsch, Alexander, Goldin, Tamara J., Goto, Kazuhisa, Grajales-Nishimura, José M., Grieve, Richard A. F., Gulick, Sean P. S., Johnson, Kirk R., Kiessling, Wolfgang, and Koeberl, Christian
- Subjects
- *
DINOSAUR extinction , *ASTEROIDS , *IMPACT of asteroids with Earth , *BIOLOGICAL extinction , *CRETACEOUS stratigraphic geology - Abstract
The Cretaceous-Paleogene boundary ∼65.5 million years ago marks one of the three largest mass extinctions in the past 500 million years. The extinction event coincided with a large asteroid impact at Chicxulub, Mexico, and occurred within the time of Deccan flood basalt volcanism in India. Here, we synthesize records of the global stratigraphy across this boundary to assess the proposed causes of the mass extinction. Notably, a single ejecta-rich deposit compositionally linked to the Chicxulub impact is globally distributed at the Cretaceous-Paleogene boundary. The temporal match between the ejecta layer and the onset of the extinctions and the agreement of ecological patterns in the fossil record with modeled environmental perturbations (for example, darkness and cooling) lead us to conclude that the Chicxulub impact triggered the mass extinction. [ABSTRACT FROM AUTHOR]
- Published
- 2010
- Full Text
- View/download PDF
7. A Transient Rise in Tropical Sea Surface Temperature Duringthe Paleocene-Eocene Thermal Maximum.
- Author
-
Zachos, James C., Wara, Michael W., Bohaty, Steven, Delaney, Margaret L., Petrizzo, Maria Rose, Brill, Amanda, Bralower, Timothy J., and Premoli-Silva, Isabella
- Subjects
- *
PROXY statements , *GREENHOUSE effect , *FORAMINIFERA , *PALEOCENE stratigraphic geology , *OXYGEN - Abstract
The Paleocene-Eocene Thermal Maximum (PETM) has been attributed to a rapid rise in greenhouse gas levels. If so, warming should have occurred at all latitudes, although amplified toward the poles. Existing records reveal an increase in high-latitude sea surface temperatures (SSTs) (8° to 10°C) and in bottom water temperatures (4° to 5°C). To date, however, the character of the tropical SST response during this event remains unconstrained. Here we address this deficiency by using paired oxygen isotope and minor element (magnesium/calcium) ratios of planktonic foraminifera from a tropical Pacific core to estimate changes in SST. Using mixed-layer foraminifera, we found that the combined proxies imply a 4° to 5°C rise in Pacific SST during the PETM. These results would necessitate a rise in atmospheric pCO[sub2] to levels three to four times as high as those estimated for the late Paleocene. [ABSTRACT FROM AUTHOR]
- Published
- 2003
- Full Text
- View/download PDF
8. Cretaceous Extinctions: Evidence Overlooked.
- Author
-
SCHULTE, PETER, ALEGRET, LAIA, ARENILLAS, IGNACIO, ARZ, JOSÉ A., BARTON, PENNY J., BOWN, PAUL R., BRALOWER, TIMOTHY J., CHRISTESON, GAIL L., CLAEYS, PHILIPPE, COCKELL, CHARLES S., COLLINS, GARETH S., DEUTSCH, ALEXANDER, GOLDIN, TAMARA J., GOTO, KAZUHISA, GRAJALES-NISHIMURA, JOSÉ M., GRIEVE, RICHARD A. F., GULICK, SEAN P. S., JOHNSON, KIRK R., KIESSLING, WOLFGANG, and KOEBERL, CHRISTIAN
- Subjects
- *
LETTERS to the editor , *EVOLUTION research - Abstract
A response by authors P. Schulte et al. to letters to the editor about their article “The Chicxulub Asteroid Impact and Mass Extinction at the Cretaceous-Paleogene Boundary,” in the March 5, 2010 issue is presented.
- Published
- 2010
- Full Text
- View/download PDF
9. Surface ocean warming and acidification driven by rapid carbon release precedes Paleocene-Eocene Thermal Maximum.
- Author
-
Babila TL, Penman DE, Standish CD, Doubrawa M, Bralower TJ, Robinson MM, Self-Trail JM, Speijer RP, Stassen P, Foster GL, and Zachos JC
- Abstract
The Paleocene-Eocene Thermal Maximum (PETM) is recognized by a major negative carbon isotope (δ
13 C) excursion (CIE) signifying an injection of isotopically light carbon into exogenic reservoirs, the mass, source, and tempo of which continue to be debated. Evidence of a transient precursor carbon release(s) has been identified in a few localities, although it remains equivocal whether there is a global signal. Here, we present foraminiferal δ13 C records from a marine continental margin section, which reveal a 1.0 to 1.5‰ negative pre-onset excursion (POE), and concomitant rise in sea surface temperature of at least 2°C and a decline in ocean pH. The recovery of both δ13 C and pH before the CIE onset and apparent absence of a POE in deep-sea records suggests a rapid (< ocean mixing time scales) carbon release, followed by recovery driven by deep-sea mixing. Carbon released during the POE is therefore likely more similar to ongoing anthropogenic emissions in mass and rate than the main CIE.- Published
- 2022
- Full Text
- View/download PDF
10. Globally distributed iridium layer preserved within the Chicxulub impact structure.
- Author
-
Goderis S, Sato H, Ferrière L, Schmitz B, Burney D, Kaskes P, Vellekoop J, Wittmann A, Schulz T, Chernonozhkin SM, Claeys P, de Graaff SJ, Déhais T, de Winter NJ, Elfman M, Feignon JG, Ishikawa A, Koeberl C, Kristiansson P, Neal CR, Owens JD, Schmieder M, Sinnesael M, Vanhaecke F, Van Malderen SJM, Bralower TJ, Gulick SPS, Kring DA, Lowery CM, Morgan JV, Smit J, and Whalen MT
- Abstract
The Cretaceous-Paleogene (K-Pg) mass extinction is marked globally by elevated concentrations of iridium, emplaced by a hypervelocity impact event 66 million years ago. Here, we report new data from four independent laboratories that reveal a positive iridium anomaly within the peak-ring sequence of the Chicxulub impact structure, in drill core recovered by IODP-ICDP Expedition 364. The highest concentration of ultrafine meteoritic matter occurs in the post-impact sediments that cover the crater peak ring, just below the lowermost Danian pelagic limestone. Within years to decades after the impact event, this part of the Chicxulub impact basin returned to a relatively low-energy depositional environment, recording in unprecedented detail the recovery of life during the succeeding millennia. The iridium layer provides a key temporal horizon precisely linking Chicxulub to K-Pg boundary sections worldwide., (Copyright © 2021 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution NonCommercial License 4.0 (CC BY-NC).)
- Published
- 2021
- Full Text
- View/download PDF
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.