Falling‐Stage Systems Tract in Tropical Carbonate Rocks

Abstract

The standard model of sequence stratigraphy postulates that the falling limb of a sea-level cycle leaves no depositional record on the shelf and upper slope -highstand and lowstand systems tracts are separated by a hiatus and erosional unconformity. There are now many examples of sediment accumulations formed during relative sealevel fall, here referred to as 'falling-stage systems tract'. This study focuses on tropical carbonates. Numerical modelling is used to identify key parameters for the development of the falling-stage systems tract and the standard-model anatomy, and to determine their stability domains in this parameter space. Well-documented case studies are used to compare model results and fi eld observations. Key parameters are the rates of sea-level fall, erosion and carbonate production with slope angle as a modifying factor. The falling-stage systems tract is favoured by low rates of fall, low rates of erosion, high rates of carbonate production, and low slope angle. The effects of subaerial and marine erosion are similar. The two variables are linearly correlated in a wide range of conditions and the sum of subaerial and marine erosion rates can be plotted on one axis after appropriate conversion. Numerical reconnaissance and fi eld observation indicate that the geologically probable space for the falling-stage systems tract is large and the phenomenon should be common in tropical carbonates.

Late Wenlock carbon isotope excursions and associated conodont fauna in the Podlasie Depression, eastern Poland: a not‐so‐big crisis?

“…The succession in the Widowo IG‐1 core appears to be of the former type, reflecting probably its relative up‐ramp position compared to the sections recording the FSST in the Midland Platform, i.e. the core represents the area where a baseline fall results in net erosion of sediments, which may supply material for the development of FSST in a downslope setting (Hunt and Tucker, , ; Schlager and Warrlich, , ). Based on these correlations, the interval recording the onset of the uppermost peak would correspond to the depositional sequence 3 (DS3, Fig.…”