Giant sediment-wave field and supercritical-flow bedforms in a Mississippian (Viséan) carbonate ramp, Tennessee-Kentucky, USA
13/12/2023 4:00 pm (London)
Hybrid event beds in the context of ancient deep-lacustrine fan models: new insights from the early Cretaceous North Falkland Basin
10/01/2024 4:00 pm (London)
Hybrid event beds (HEBs) are texturally and compositionally-diverse deposits preserved within deepwater settings. They are deposited by flows exhibiting ‘mixed behaviour’, forming complex, but ordered, successions of sandstone and mudstone, which are often challenging to predict in the subsurface. HEBs are well-documented in deep-marine settings, where they are well-known and characterised as effective fluid transmissibility barriers and baffles in reservoirs. By comparison, there are far-fewer studies of HEBs from deep-lacustrine settings (both ancient and modern), where their character and distribution remain relatively under-explored.
This presentation explores the analysis of 3D seismic data, wireline logs and core from a series of ancient deep-lacustrine fan systems in the early Cretaceous strata of the North Falkland Basin (Falkland Islands). From this analysis, deep-lacustrine HEBs are observed to comprise the same idealized sequence of the ‘H1–H5’ divisions as those reported in deep-marine settings. However, in this dataset H3 ‘debrite’ units can be sub-divided into ‘H3a–H3c’, based on: sharp or erosional intra-H3 contacts, bulk lithology, mud-content and discrete sedimentary textures. This study interprets the H3a–H3c sub-units as the products of multiple flow components formed through rearward longitudinal flow transformation processes, during the emplacement of a single HEB. HEBs are observed within lobe fringes, where flow types, energies, and transport mechanisms diversify as a result of flow transformation. The temporal context of HEB occurrences is considered in relation to stages of fan evolution, including: the initiation, growth (I), growth (II), by-pass, abandonment and termination phases. HEBs are observed in either the initiation phase, where flow interaction and erosion of initial substrates promoted mixed flow behaviour, or in the abandonment phase as facies belt retreated landward. Investigating these relationships provides a new understanding of HEB distribution and character in deep-lacustrine basins, and importantly the ancient deep-lacustrine subsurface.
Understanding Facies and Sequence Architecture in Sierra de Albarracín-Aliaga, Spain: 2023 IAS Summer School
24/01/2024 4:00 pm (London)
Join us for a recap of the 2023 IAS Summer School held in Spain in October, 2023! This presentation will provide an overview of the summer school as well as scientific findings from the participants.