Supercontinents

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Rotation poles (Euler poles), about which lithospheric plates are displaced, can be determined from transform faults interpreted from satellite altimeter-derived images. All reconstructions are based on the generally held view that Earth has maintained a constant radius (although this is questioned by some who contend that the earth has progressively expanded). For older periods, scientists rely on the following to establish, or at least infer, continental correlations:

• Linking of orogenic belts and intracratonic structures (e.g., major shear zones of the same age and displacement sense)—accurate dating is unfortunately lacking from many Precambrian terrains, hindering such correlations. Regional aeromagnetic data is valuable in comparing lithological trends and structural elements as basement rocks below superficial cover and sedimentary basins are imaged. Regional gravity data highlights major crustal structures.
• Mafic dikes—dike swarms (readily discernable on aero-magnetic images) may be traced from one craton to another. Dikes may converge on an area above the center of a former mantle plume.
• Common rock types, ages, and fossil assemblages in sedimentary rocks on conjugate margins—provenance studies and ages of detrital zircons for sedimentary basins provide information concerning the source terrains for sedimentary basins. Sedimentary source rocks absent from the craton the basin is situated in may be found on previously contiguous continents.
• Paleomagnetism

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