Trans-Hudson orogeny Trans-Hudson orogeny The Trans-Hudson orogeny or Trans-Hudsonian orogeny was the major mountain building event (orogeny) that formed the Precambrian Canadian Shield, the North American Craton (also called Laurentia), and the forging of the initial North American continent. It gave rise to the Trans-Hudson orogen (THO), or Trans-Hudson Orogen Transect (THOT), (also referred to as the Trans-Hudsonian Suture Zone (THSZ) or Trans-Hudson suture) which is the largest Paleoproterozoic orogenic belt in the world. It consists of a network of belts that were formed by Proterozoic crustal accretion and the collision of pre-existing Archean continents. The event occurred 2.0-1.8 billion years ago.
Sonoma orogeny arcs, composed of volcanic and volcaniclastic strata and paired geotectonically with Sonoma accretionary prisms to the east, are present in the Klamath-Sierran region of the Cordilleran orogen to the south of volcanic cover in the Pacific Northwest. Burchfiel and Davis presented a detailed model relating the Sonoma orogeny to convergent plate tectonic processes. They postulated an east-dipping subduction zone beneath a magmatic arc to the west of the continent. In this scheme, a back-arc basin floored by oceanic crust lay between the arc and the continent. The Sonoma orogeny involved closure of this basin and a process by which the