Stratigraphic and Sedimentary Architecture of Tectonically Influenced Shallow-Water Delta Complexes: An Example From the Lower Cretaceous, Maestrat Basin, Spain

Abstract

A multidisciplinary approach of remote sensing, field data and structural restoration and validation techniques are being used to evaluate the controls on delta mouth bar sandbody architecture in a superbly exposed succession of deltaic facies and genetically related carbonates (Lower Cretaceous, Xert Formation) in the Galve sub-basin (Aliaga, Teruel), eastern Spain. This presentation puts forward architectural element models for individual shallow-water delta mouth bar complexes (small scale) and multiple stacked shallow-water mouth bar complexes (large scale) in order to show the variation at both oilfield and local scale.

The Galve rift sub-basin formed from the Oxfordian through to the Albian, during which, up to 2km of terrestrial to marine, siliciclastic and carbonate rocks were deposited. The basin was inverted during the Palaeogene leaving a strong E-W structural fabric. However, the Galve sub-basin has a N-S striking anticline, with associated fault and syncline with Triassic Keuper facies (brecciated Gypsum and rafted Dolomites) in the core of the anticline. We hypothesise that these structures are the result of salt tectonics and the potential influence of synsedimentary salt tectonics on the architecture and stacking patterns of the delta sandbodies is being evaluated.

The shallow-water delta succession consists of at least five parasequences deposited during a longer term transgressive phase. It was strongly river dominated prograding into a shallow (2m at river mouth) predominantly carbonate shelf setting. A combination of a low relief pro-delta shelf and limited accommodation space led to relatively thin mouth bars (2-4m) and mouth bar complexes (4-6m). However, increases in accommodation space have led to the development of up to 15m thick amalgamated delta front sandbody complexes. Further rises in relative sea level and a change in sediment input point resulted in stacked delta front sandbody complexes in the north of the basin. The first of these bodies (parasequence set) were deposited over an area >72km² with cumulative sand thicknesses up to 25m. The later parasequences consist of stacked sand bodies (up to 15m thick) deposited over an area >36km² with cumulative stacked sand body thicknesses up to 35m. The development of a high-resolution correlative framework has allowed for the degree of sandbody amalgamation to be determined and the identification of stacked sandbody complexes.

AAPG Datapages/Search and Discovery Article #90323 ©2018 AAPG Annual Convention and Exhibition, Salt Lake City, Utah, May 20-23, 2018