PALEOZOIC CORDILLERAN GEOSYNCLINE 



81 



vanian data in the western United States from which the maps of Figs. 

 6.5-6.7 were constructed lead to the suggestion that the Antler orogenic 

 belt of Nevada extends northward through western Idaho and eastern 

 Oregon and Washington to the Shuswap terrane of southern British 

 Columbia. If so, we would infer that the Shuswap orogeny is of the same 

 age as the Antler; that is, it started in Late Devonian and continued vigor- 

 ously through the Mississippian and early Pennsylvanian. The Shuswap 

 is marked by considerable metamorphism and perhaps batholithic intru- 

 sion and related processes, whereas the Antler belt is marked especially 

 by great thrust sheets. 



The term Shuswap orogeny as here used will denote tectonic events 

 in the Shuswap terrane region that occurred during the same time 

 approximately as those of the Antler belt, and the term Cariboo orogeny 

 as proposed by White will be considered to have wider and longer conno- 

 tation. 



White (1959) summarizes information which suggests that the Shu- 

 swap belt extends into northern British Columbia and the Yukon Terri- 

 tory, and when so conceived the Antler and Shuswap orogenic belt is 

 continuous from southern California to Alaska. 



EUGEOSYNCLINE IN SOUTHEASTERN ALASKA, NORTHERN BRITISH 

 COLUMBIA AND THE YUKON 



Southeastern Alaska. The Paleozoic rocks in southeastern Alaska from 

 54° 30' to 60° N. Lat. are of geosynclinal thickness and make up a 

 number of formations of Ordovician, Silurian, Devonian, Mississippian, 

 Pennsylvanian, and Permian ages (Buddington and Chapin, 1929). The 

 stratigraphic succession is given in the table on p. 82. 



One of the commonest types of rock is andesite in various forms. It 

 occurs in at least seven formations of Permian age to Ordovician, and 

 perhaps older. Many of the volcanic rocks are now greenstone schist. 

 Pillow lava is abundant in the Lower and Middle Ordovician, Silurian, 

 Middle and Upper Devonian, Lower Permian, and Upper Triassic. 



The other predominant rock types are sheared graywacke, slate, and 

 phyllite. The vast amount of greenish graywacke with associated slate is 



SOUTHERN KLAMATH MOUNTAINS 



NORTHERN KLAMATH MTS . 





REDDING QUAD. 

 (HINDS ET AL. ) 



WEAVERVTLLE QUAD. 

 (HINDS ET AJ.. ) 



WELLS EJ. AL. 



U. TRIASSIC 







APPLEGATE GROUP, METAVOLCANICS 

 AND METASEDIMENTS. FORMERLY 

 CALLED DEVONIAN OR CARBONIFEROUS 



PERMIAN 



NOSONI VOLCANICS_ 







McCLOUD LIMESTONE 



MISSISSIPPIAN 



BAIRD FM. 



DRAGDON FM. WITH BASS 

 MOUNTAIN BASALT 



BRAGDON FM. 





DEVONIAN 



KENNETT FM. 



DEVONIAN LIMESTONE PATCHES 



SILURIAN 



COPLEY META-ANDESITE 

 (POSSIBLY SILURIAN) 



COPLEY META-ANDESITE 

 CHANCHELLULA FM. 

 (POSSIBLY SILURIAN) 



SALMON SCHIST 

 ABRAMS SCHIST 



SILURIAN STRATA (NOT NAMED) 



PRE -SILURIAN 





HIGHLY FOLIATED SCHIST 



Fig. 6.13. Correlation of Paleozoic formations in Klamath Mountains. 



the most striking feature of the stratigraphic sequence of southeastern 

 Alaska. Graywacke is found in every system of the Paleozoic and Meso- 

 zoic, and in many places it is difficult or impossible to tell one graywacke 

 unit from another. 



Limestone forms a very considerable part of each Paleozoic formation 

 except the Ordovician. The thickest unit is in the Upper Silurian and is a 

 very high calcite variety. Some limestone carries considerable chert. 



Beds of cobble and boulder conglomerate form conspicuous and thick 

 members of the Silurian and Devonian formations. A peculiar but com- 

 mon form is composed of andesite and limestone pebbles and cobbles in 

 a tuffaceous matrix. The same lithology is found in the Middle Devonian. 

 Coarse conglomerate beds occur at the base of the Devonian. 



Another characteristic lithology in the Paleozoic systems in southeastern 

 Alaska is coarse, waterworn intraformational limestone conglomerate. 

 Beds occur in the Silurian, Devonian, Permian, and Triassic formations, 

 and in all of them the cobbles of limestone carry the same fauna as the 

 formation in which the conglomerate occurs. Buddington believes the 

 intraformational conglomerates originated from crustal movements ac- 

 companying the volcanic activity during these periods. 



Black slate and argillite are widely distributed, and thin-layered black 

 chert several hundred feet thick occurs in the Ordovician and Missis- 



