Crustal Architecture

At Getech crustal architecture is the definition of crustal types using potential field and seismic data to identify composition, thickness and structure. This affects heat flow, margin evolution and thereby accommodation space, but is also a fundamental constraint on high-resolution plate modelling.

Getech’s expertise in defining and understanding the world’s crustal architecture has been distilled into our Global Crustal Architecture spatial database. This is a companion data layer to our Global Plate Model. It comprises the Present Day distribution of crustal types, and is designed to support the plate modelling process by providing extra geological constraints. The data layer also includes information not directly required within the plate model databases, however, this information is critical in order to understand the thickness and composition of the crust.

The Getech Crustal Architecture spatial database divides the Earth’s crust into four main domains: continental; attenuated; transitional, and oceanic. Each domain is then further sub-divided into crustal sub-types. The “continental” domain includes all areas of continental crust, the domain is predominantly granitic in composition, of greater than 35 km thickness and has a mean density around 2,700 kg/m³.

Continental Domain

The continental domain is sub-divided into compressional regimes including accretionary complexes, collisional complexes and continental volcanic arcs. Cratons and ancient mobile belts are differentiated in continental interiors.

Attenuated and Transitional Domains

Passive margin architecture includes the attenuated and transitional domains, with the continent-ocean transition as a unique zone rather than a linear boundary. The attenuated zone is stretched continental crust with minimal addition of material, and thickness in the range of 10–35 km. The transitional domain includes definition of magma-rich and magma-poor passive margins depending upon the presence of seaward-dipping volcanic and volcaniclastic sequences, igneous intrusion and magmatic underplating. The transitional domain is characterised by a bulk density increase when compared to continental crust and can be thinned to less than 10 km.

Oceanic Domain

The oceanic domain contains mostly basaltic crust of 7 km thickness; it also includes thickened oceanic and oceanic volcanic arc as sub-types.

A complementary Crustal Boundaries database contains linear boundaries between the different crustal domains, defined using potential field data, geophysical inversions for depth-to-basement and depth-to-Moho, seismic profiles and literature examples.

In our classification, the limit of unstretched crust represents the onset of deformation associated with the most recent rifting event; the limit of oceanic crust marks the presence of the first true oceanic crust, and the onset of transitional affinity marks the boundary between the attenuated and transitional domains.

Crustal architecture spatial database example from East Africa (Getech’s Tectonic Evolution of East Africa study). Crustal types are defined from potential field grids, 2D gravity and magnetic profiles, depth to moho grids and seismic constraints.

Crustal architecture spatial database example from East Africa (Getech’s Tectonic Evolution of East Africa Study). Crustal types are defined from potential field grids, 2D gravity and magnetic profiles, depth-to-Moho grids, and seismic constraints.

This is an ongoing project with more detailed analysis and mapping through our in-depth Regional Reports.

To find out more about Getech’s Crustal Architecture Expertise, please contact us at info@getech.com.