کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
9522253 1348287 2005 15 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
The Upper Valanginian (Early Cretaceous) positive carbon-isotope event recorded in terrestrial plants
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات علوم زمین و سیاره ای (عمومی)
پیش نمایش صفحه اول مقاله
The Upper Valanginian (Early Cretaceous) positive carbon-isotope event recorded in terrestrial plants
چکیده انگلیسی
Our understanding of the ancient ocean-atmosphere system has focused on oceanic proxies. However, the study of terrestrial proxies is equally necessary to constrain our understanding of ancient climates and linkages between the terrestrial and oceanic carbon reservoirs. We have analyzed carbon-isotope ratios from fossil plant material through the Valanginian and Lower Hauterivian from a shallow-marine, ammonite-constrained succession in the Crimean Peninsula of the southern Ukraine in order to determine if the Upper Valanginian positive carbon-isotope excursion is expressed in the atmosphere. δ13Cplant values fluctuate around − 23‰ to − 22‰ for the Valanginian-Hauterivian, except during the Upper Valanginian where δ13Cplant values record a positive excursion to ∼− 18‰. Based upon ammonite biostratigraphy from Crimea, and in conjunction with a composite Tethyan marine δ13Ccarb curve, several conclusions can be drawn: (1) the δ13Cplant record indicates that the atmospheric carbon reservoir was affected; (2) the defined ammonite correlations between Europe and Crimea are synchronous; and (3) a change in photosynthetic carbon-isotope fractionation, caused by a decrease in atmospheric pCO2, occurred during the Upper Valanginian positive δ13C excursion. Our new data, combined with other paleoenvironmental and paleoclimatic information, indicate that the Upper Valanginian was a cool period (icehouse) and highlights that the Cretaceous period was interrupted by periods of cooling and was not an equable climate as previously thought.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Earth and Planetary Science Letters - Volume 240, Issue 2, 1 December 2005, Pages 495-509
نویسندگان
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