A high-resolution carbon-isotope record of the Turonian stage correlated to a siliciclastic basin fill: Implications for mid-Cretaceous sea-level change

D. Uličný, I. Jarvis, D. R. Gröcke, S. Čech, J. Laurin, K. Olde, J. Trabucho-Alexandre, L. Švábenická, N. Pedentchouk

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37 Citations (Scopus)

Abstract

Turonian strata of the Bohemian Cretaceous Basin, Central Europe, preserve a basin-scale record of shoreline transgressions and regressions, previously interpreted to have been strongly influenced by short-term eustatic cycles. Here, nearshore siliciclastic strata in two separate sub-basins are correlated to a multi-stratigraphic dataset generated from a new research core (Bch-1) drilled in offshore marine sediments of the central basin. A high-resolution δ13Corg record from Bch-1 is presented along with major- and minor-element proxies, TOC, carbonate content, terrestrial to marine palynomorph ratios, and detailed macro- and microfossil biostratigraphy. The 400m thick Turonian through Lower Coniacian interval permits correlation to the highest-resolution C-isotope curves available: all carbon-isotope events demonstrated by δ13Ccarb studies in the British Chalk, NW Germany and other reference sections in Europe are recognized in the δ13Corg curve from Bch-1.A number of short-term, basin-wide regressions in the Bohemian Cretaceous Basin, most likely reflecting eustatic falls, show a recurrence interval of 100. kyr or less. This is an order of magnitude shorter than the timing of sea-level falls inferred from the New Jersey margin and the Apulian platform, interpreted to be driven by glacioeustacy. The estimated magnitude of the Bohemian Basin sea-level falls, typically 10-20. m and generally <. 40. m, indicates that the 2.4. Myr period suggested by others to generate 3rd-order cycles, is too long to be the principal cycle generating unconformities in rapidly-subsiding basins, where the rate of eustatic fall must exceed the subsidence rate. Unconformities in low-accommodation settings such as passive margins most likely represent amalgamated records of multiple cycles of sea-level fluctuations of 100. kyr scale, recognizable only in high-resolution datasets from expanded successions. Comparison of the δ13C excursions to the interpreted sea-level record has not yielded a clear causal link. A long-term 'background' δ13C cycle shows a duration close to the 2.4Myr long-eccentricity cycle, and shorter-term (1Myr scale) highs and lows in δ13C appear to broadly correspond to intervals characterised by more pronounced short-term sea-level highs and lows, respectively. However, on the scale of intermediate to short-term δ13C fluctuations, no systematic relationship between δ13C and sea-level change can be demonstrated.

Original languageEnglish
Pages (from-to)42-58
Number of pages17
JournalPalaeogeography, Palaeoclimatology, Palaeoecology
Volume405
DOIs
Publication statusPublished - 1 Jul 2014
Externally publishedYes

Keywords

  • Bohemian cretaceous basin
  • Carbon isotopes
  • Eustasy
  • Greenhouse climate
  • Sequence stratigraphy
  • Turonian

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