96-2 Halokinetic Sequences – Where We’ve Been and Where Next?

Session: Twenty-Seven Years of Advances in Understanding Salt-Sediment Interaction: A Legacy of Katherine A. Giles

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Halokinetic sequences (HS) were first defined in 2002 by Kate Giles and Tim Lawton based on outcrops in La Popa Basin, Mexico. They are unconformity-bound successions of upturned and thinned strata within less than 1 km from steep passive diapirs, formed due to fluctuations in the ratio between salt-rise and sediment-accumulation rates. Subsequent work by Kate, numerous colleagues and students, and other research groups elucidated many aspects of this near-salt deformation. This included: (1) recognition of two different styles, namely hook and wedge HS; (2) identification and characterization of two corresponding types of composite halokinetic sequences (CHS), specifically tabular and tapered CHS; (3) their influence on facies distribution in different depositional environments; (4) the kinematics and geometries of near-diapir drape folding; (5) the small-scale deformation associated with the development of HS; and (6) the distinction between CHS and larger, minibasin-scale stratigraphic successions. Moreover, recognition of HS in global salt-bearing orogenic belts has allowed researchers to understand how preexisting diapirs have influenced contractional deformation.

Despite this progress, there are still fundamental questions that need to be addressed. First, why do we see two end-member geometries, with little to no examples of intermediate styles? Is it really as simple as whether the ratio between salt-rise and sediment-accumulation rates is greater or less than 1? Second, the focus to date has been on this ratio and thus relative rates. Yet single CHS have been interpreted to span time scales that range from a fourth-order sea-level cycle to multiple third-order cycles. So what is the role of the absolute values of these rates, whether salt-rise or sediment-accumulation, over time? Third, the same ratio apparently controls not just the type of HS that forms but also, at a larger scale, the dip of the salt-sediment interface, i.e., whether a diapir grows vertically, narrows or flares upward, or is emplaced laterally as a salt sheet. Can we really have it both ways and, if so, is it just a matter of scale or something else? How do these two processes interact? Finally, at a more practical level, we need to use a combination of wells and 3D seismic data in producing fields to determine the three-dimensional influence of stacked CHS on reservoir geometry, column heights, local seals, and thus hydrocarbon distribution.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-5733

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