Carbonate delta drift: A new sediment drift type

Thomas Lüdmann*, Christian Betzler, Gregor P. Eberli, Jesús Reolid, John J.G. Reijmer, Craig R. Sloss, Or M. Bialik, Carlos A. Alvarez-Zarikian, Montserrat Alonso-García, Clara L. Blättler, Junhua Adam Guo, Sébastien Haffen, Senay Horozal, Mayuri Inoue, Luigi Jovane, Dick Kroon, Luca Lanci, Juan Carlos Laya, Anna Ling Hui Mee, Masatoshi NakakuniB. Nagender Nath, Kaoru Niino, Loren M. Petruny, Santi D. Pratiwi, Angela L. Slagle, Xiang Su, Peter K. Swart, James D. Wright, Zhengquan Yao, Jeremy R. Young

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review

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Based on high-resolution reflection seismic and core data from IODP Expedition 359 we present a new channel-related drift type attached to a carbonate platform slope, which we termed delta drift. Like a river delta, it is comprised of several stacked lobes and connected to a point source. The delta drifts were deposited at the exit of two gateways that connect the Inner Sea of the Maldives carbonate platform with the open ocean. The channels served as conduits focusing and accelerating the water flow; Entrained material was deposited at their mouth where the flows relaxed. The lobe-shaped calcareous sediment drifts must have formed under persistent water through flow. Sediment supply was relatively high and continuous, resulting in an average sedimentation rate of 17 cm ka−1. The two delta drifts occupy 342 and 384 km2, respectively; with a depositional relief of approximately 500 m. They have a sigmoidal clinoform reflection pattern with a particular convex upward bending of the foresets. In the Maldives the drift onset marks the transition from a sea-level controlled to a progressively current dominated depositional regime. This major event occurred in the Serravallian about 13 Ma ago, leading to the partial drowning of the carbonate platform and the creation of shallow seaways. The initial bank-enclosed topography resembles an “empty bucket” geometry which is rapidly filled by the drift sediments that aggrade and prograde into the basin. Thereby the depositional environment of the delta drifts changes from deep water (>500) to shallow-water conditions at their topsets, indicated by the overall coarsening upward trend in grain size and the presence of shallow water large benthic foraminifers at their top.

Original languageEnglish
Pages (from-to)98-111
Number of pages14
JournalMarine Geology
Early online date23 Apr 2018
Publication statusPublished - 1 Jul 2018


  • Bottom current
  • Carbonate platform
  • Clinoform
  • Delta drift
  • Drift sedimentation
  • Maldives


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