Aquifer-eustasy as the main driver of short-term sea-level fluctuations during Cretaceous hothouse climate phases

Benjamin Sames, Michael Wagreich, Clinton P. Conrad, Shahid Iqbal

Publications: Contribution to journalArticlePeer Reviewed

Abstract

A review of short-term (<3 myr: c. 100 kyr to 2.4 myr) Cretaceous sea-level fluctuations of several tens of metres indicates recent fundamental progress in understanding the underlying mechanisms for eustasy, both in timing and in correlation. Cretaceous third- and fourth-order hothouse sea-level changes, the sequence-stratigraphic framework, are linked to Milankovitch-type climate cycles, especially the longer-period sequence-building bands of 405 kyr and 1.2 myr. In the absence of continental ice sheets during Cretaceous hothouse phases (e.g. Cenomanian–Turonian), growing evidence indicates groundwater-related sea-level cycles: (1) the existence of Milankovitch-type humid-arid climate oscillations, proven via intense humid weathering records during times of regression and sea-level lowstands; (2) missing or inverse relationships of sea-level and the marine δ18O archives, i.e. the lack of a pronounced positive excursion, cooling signal during sea-level lowstands; and (3) the anti-phase relationship of sea and lake levels, attesting to high groundwater levels and charged continental aquifers during sea-level lowstands. This substantiates the aquifer-eustasy hypothesis. Rates of aquifer-eustatic sea-level change remain hard to decipher; however, reconstructions range from a very conservative minimum estimate of 0.04 mm a−1 (longer time intervals) to 0.7 mm a−1 (shorter, probably asymmetric cycles). Remarkably, aquifer-eustasy is recognized as a significant component for the Anthropocene sea-level budget.
Original languageEnglish
Pages (from-to)9-38
Number of pages30
JournalGeological Society Special Publications
Volume498
Issue number1
DOIs
Publication statusPublished - 2020

Austrian Fields of Science 2012

  • 105304 Hydrology
  • 105204 Climatology
  • 105121 Sedimentology
  • 105306 Oceanography

Keywords

  • Climate change
  • Sea level
  • greenhouse climate
  • Aquifer-eustasy
  • Cretaceous greenhouse
  • Milankovitch periodicities

Cite this