Basement Structure and Composition
New interpretive maps of basement architecture, composition and structural fabric can be used to better understand the nature of basement across a region.
Basement architecture, structure and composition have been constructed through the integrated interpretation of all available geological and geophysical datasets, including outcrop, wells, geochronology, seismic, gravity, magnetic and bathymetry datasets
Direct geological observations (outcrop, wells or dredge samples) are compared with potential field characteristics to identify relationships between observed basement composition and rock properties (density or magnetic susceptibility).
Typically, there are correlations between observed structural fabrics and equivalent trends in the potential field data, and between the observed seismic characteristics. The potential field data are used to predict basement terrain distribution, basement composition and structural fabric in areas where no other datasets are currently available.
Basement architecture is mapped using basement outcrop, potential field, multispectral imagery and DEM data. The mapped structures include basement faults, dikes and structural trends and lineaments that can be identified in the potential field data. Basement trends associated with the younger orogens have a profound affect on Late Jurassic‒Early Cretaceous margin development. This map highlights potential variations in radiogenic basement-derived heat flow which might have influenced the thermal evolution of the basin and hence petroleum source rock maturation.
For example, younger fracture zones typically correlate with a significant change in basement structural trend. In addition, a linkage is evident between basement fabric orientation and basin geometry implying basement structures have significantly influenced basin evolution and patterns of sediment deposition throughout time.
New tectonic models and recent basin reconstructions also take into account the Moho discontinuity because a complete earth model requires both basement and Moho structural horizons in order to build viable interpretations. Gravity and magnetic data reveal much deeper structure than conventional reflection seismic data because they reveal lateral variations in subsurface density and magnetic susceptibility, respectively, indicating depth of source body.
Modern exploration workflows include the characteristic types of crust: craton, platform, orogenic belt, continental rift, marginal, and ocean basin.
They constrain upper crustal thickness and basement composition, magnitude of crustal extension, and the upper crustal contribution to heat-flow for basin modeling and so the basement architecture can be characterized by crustal types based on magnetic basement structure integrated with gravity data and geological outcrop.