ANATOMY OF NORTH-AMERICA - THEMATIC GEOLOGIC PORTRAYALS OF THE CONTINENT

Six thematic tectonic maps are used to analyse the makeup of the North American continent. Themes are: (1) major tectonic elements of the continent, (2) time of last major deformation, (3) time of first major deformation, (4) miogeoclines and terranes by kindred, (5) suture zones and terrane boundaries by age, and (6) time of accretion. Features illustrated include distribution of orogenic belts and their extensions beneath cover sequences to the continental edge, contrast between juvenile and reworked crust in orogenic belts, geometry of ancient continental margins, distribution and classification of accreted terranes, geometry of suture zones and courses of ancient oceans, and how the continent evolved from an assemblage of Archean minicontinents to its present configuration. It is suggested that essentially similar plate tectonic processes controlled continental breakup and assembly from the Archean onwards, albeit with gradual increase in size of continental lithospheric plates and quantitative change in other parameters such as heatflow and character of the mantle.