D'Entrecasteaux Islands () are situated near the eastern tip of New Guinea in the Solomon Sea in Milne Bay Province of Papua New Guinea. The group spans a distance of , has a total land area of approximately and is separated from the Papua New Guinea mainland by the wide Ward Hunt Strait in the north and the wide Goschen Strait in the south. D'Entrecasteaux Islands show signs of volcanism.
Description
250px|thumb|Topographic map of D'Entrecasteaux Islands. Large islands from Northwest to Southeast: [[Goodenough Island|Goodenough, Fergusson and Normanby.]]
The three principal islands, from northwest to southeast, are Goodenough (Nidula), then across Moresby Strait to Fergusson (Moratau), the largest of the three, and across Dawson Strait to Normanby Island (Duau There are geothermal areas in the south east area of Goodenough Island and the Bwabwadana and Iamalele on Fergusson Island. A particularly active hot springs is located at Deidei on Fergusson.
Between Fergusson and Normanby Islands the Dawson Straits Group has several volcanic centres that may define a partly submerged caldera; one of the cones on southwestern Fergusson Island may have erupted in 1350.
Geology
Geologically the islands are largely made up of rock that probably once belonged to the northern edge of the Australian plate that was thrust deep into the Earth's crust by plate collision.
The burial of these rocks to great depths (where they also encountered correspondingly high temperatures) metamorphosed the rocks to eclogite facies: >2GPa and >700˚C. Specifically, these islands play host to the youngest known coesite-eclogite sample; CA-TIMS dating of zircons within this sample dates its formation to ~5Ma, meaning it has been exhumed from a depth of ~100 km at the remarkable rate of ~20mm/yr.
The rock at the centre of the tall domes in these islands was thus recently very deep in the Earth. Over a very short time, geologically speaking, these packets of rocks have ascended through the Earth's shallow mantle and pushed through the crust to form the gneiss domes we find today – the vestiges of the crust these massifs have thrust through are still draped as carapaces over the edges of the domes.
These islands are thought to be geophysically significant because they lie immediately ahead of the westernmost rift tip of the Woodlark spreading centre, which has been propagating westwards into the continent. The D'Entrecasteaux thus represent a stage of continental breakup just preceding fully-fledged volcanic spreading.
History
The group was named for the French navigator Antoine Raymond Joseph de Bruni d'Entrecasteaux, who, in his ship the Espérance, passed through the area in 1792 while searching for his missing compatriot, Jean-François de Galaup, comte de La Pérouse. Almost a century later, in 1874, Captain John Moresby of made a running survey of the west coast of the islands and became the first European to make landfall.
From Dobu Island, local men were recruited to work in gold mines and on copra plantations. In 1891, the Methodist Church of Australia established a mission station on Dobu Island. Another mission was established in 1898 at Bwaidoga, Mud Bay, on the south coast of Goodenough Island.