A broad ridge of Precambrian and Palaeozoic igneous and metamorphic rocks extends for 450 km along the east side of Cape York Peninsula, from the Mitchell River in the south to Temple Bay. From Cape York a submerged ridge of Palaeozoic igneous rocks extends across Torres Strait to Papua. The metamorphic rocks crop out in four separate areas, but are all probably part of the same Precambrian sedimentary sequence. They have been subjected to high-temperature/lowpressure regional metamorphism, and the metamorphic grade increases eastwards from phyllite of the greenschist facies to gneiss of the amphibole facies. They consist mainly of mica schist and quartzite, with local occurrences of greenstone, calc-silicate rocks, marble, and iron-rich rocks, and are intruded by dolerite in the south. The Cape York Peninsula Batholith is composed of adamellite and subordinate granodiorite and granite. It is intrusive into the discontinuous belt of metamorphic rocks over a distance of at least 400 km. The age of the batholith is uncertain, but preliminary isotopic analyses indicate that it is probably middle Palaeozoic. In the Lower Carboniferous coal-bearing sediments were laid down in small basins. The thick sheets of acid welded tuff and subordinate lavas in Torres Strait, which are intruded by large bodies of granite and porphyritic microgranite, are probably Carboniferous, and the acid pyroclastics and associated high-level granites south of Temple Bay are Carboniferous or Permian. In the Mesozoic, coarse sandstone and conglomerate followed by finer sediments were laid down in the trough between the two basement ridges. Tertiary uplift on faults along the east side of the peninsula resulted in the deposition of poorly consolidated sandstone and conglomerate. A plug of olivine nephelinite was emplaced near the faults, and in the Pleistocene olivine basalt lava and pyroclastics were erupted from small volcanoes in the northeastern part of Torres Strait. Most of the main structures in the peninsula, such as the fold axes and foliation in the metamorphics, the faults, and the long axis of the batholith, have a northerly trend. The Palmerville Fault is a major structure which has been active from Silurian time onwards. Alluvial and reef gold were mined extensively in Cape York Peninsula and in Torres Strait late in the 19th century, and small quantities of wolfram and alluvial tin have also been won. The deposits of iron and manganese near Iron Range and the silica sand on the Mesozoic sediments north of Temple Bay have not yet been exploited. Traces of antimony, arsenic, copper, lead, zinc, and molybdenum have been reported, and occurrences of bauxite, coal, mica, heavy-mineral beach sand, and limestone are known.
