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The southern Black Coast, in the southeastern Antarctic Peninsula, includes the Wegener Range, Carey Range, and northern Dana Mountains. The geology of the area is similar to that of the Lassiter Coast, Orville Coast, English Coast, and eastern Ellsworth Land, all of which lie farther south in the peninsula. All these areas are part of the Andean magmatic and deformational belt. Except for some late Paleozoic or Triassic sedimentary rocks in the English Coast, the oldest rocks in the southern Antarctic Peninsula are Middle and Upper Jurassic fine-grained volcaniclastic sedimentary rocks of the Latady Formation and interlayered silicicto intermediate-composition rocks of the Mount Poster Formation. Siltstone, slate, and fine-grained sandstone dominate in the Latady Formation; ash-flow tuff, lava flows, and dikes dominate in the Mount Poster Formation. The Mount Poster Formation was deposited as a magmatic arc, southeast of which a shallow marine back-arc basin accumulated sediment that formed the Latady Formation. The magmatic arc, which now underlies the axis of the southern Antarctic Peninsula, resulted from southeastward subduction of the southern Pacific oceanic lithosphere beneath the Antarctic Peninsula The Jurassic sedimentary and volcanic rocks were tightly folded along northto north-northeast-trending axes as subduction continued. Late during deformation, in Early Cretaceous time, plutons and dikes were emplaced into the rocks of the Jurassic arc and back-arc basin. The intrusive rocks define either another magmatic arc that formed during continued subduction or a late phase of the Jurassic magmatic arc; any volcanic material that may have accompanied the Early Cretaceous intrusive activity, however, has not been identified in the southern Antarctic Peninsula. In the southern Black Coast area, exposed plutons consist of the west Wegener Range batholith, the east Wegener Range batholith, and the Werner batholith. Granite and granodiorite are the most abundant rock types in these plutons, but each pluton has a thin border facies of mafic rocks. The Jurassic sedimentary and volcanic wall rocks are contact metamorphosed over wider zones than farther south in the Antarctic Peninsula, where plutons are less abundant. Altered and mineralized plutonic rocks are widely scattered in the area but do not appear to be of economic value. Slightly mineralized, sheared phyllic-argillic zones, similar to those in the Lassiter Coast copper deposit to the south, occur in the western Carey Range. U.S. Geological Survey. Present address is Department of Geology, Sonoma State University, Rohnert Park, Calif. 94928. 3Present address is 7045 SW. 62nd Place, Portland, Oregon, 97219 INTRODUCTION The southern Black Coast, which lies along the Weddell Sea on the eastern flank of the southern Antarctic Peninsula (figs. 1, 2), includes the Wegener Range, Carey Range, and northern Dana Mountains. The area was first visited and geologically mapped in reconnaissance during the 1972-73 austral summer by a U.S. Geological Survey field party that included the authors. The northern Lassiter Coast, to the south, also was mapped at this time (Rowley, 1973). The Antarctic Peninsula is part of the Andean magmatic and deformational belt of Early Jurassic to late Tertiary age, which extends from the Andes of South America southward through the Scotia arc and Antarctic Peninsula, and from there westward through Ellsworth Land, Marie Byrd Land, and the western rim of the Pacific Ocean (Craddock, 1969, 1982; Herron and Tucholke, 1976; Craddock and Hollister, 1976; LeMasurier and Wade, 1976; LeMasurier and Rex, 1982; Cooper and others, 1982; Rowley, 1983). The geology of the southern Black Coast (Rowley, 1973; Kamenev, 1975; Rowley and Williams, 1982) is similar to that of the Lassiter Coast, Orville Coast, English Coast, and eastern Ellsworth Land, which lie successively farther south and west (Williams and others, 1972; Laudon and others, 1964, 1969; Laudon, 1972; Rowley, 1978; Thomson and others, 1978; Rowley, Vennum, and others, 1983; Rowley and others, 1985). Except for some late Paleozoic or Triassic sedimentary rocks in the English Coast (Laudon and others, 1985), the oldest rocks of this overall region are Middle and Upper Jurassic volcaniclastic sedimentary rocks of the Latady Formation and intertonguing silicicto intermediate-composition volcanic rocks of the Mount Poster Formation of the Antarctic Peninsula Volcanic Group. These rocks were tightly folded and later intruded by Lower Cretaceous plutons and dikes. The area! proportions of plutonic rocks progressively increases northward through the southern Antarctic Peninsula; l GEOLOGY, MINERAL RESOURCES, SOUTHERN ANTARCTIC PENINSULA, EASTERN ELLSWORTH LAND

Studies of the geology and mineral resources of the southern Antarctic Peninsula and eastern Ellsworth Land, Antarctica