Tertiary igneous rocks between Scoresby Sund and Kap Gustav Holm, East Greenland

The discovery of plutonic centres of Tertiary igneous rocks at Kangerdlugssuaq, and along the margin of the coastal mountains and on some of the offshore islands between Kap Gustav Holm and Kangerdlugssuaq, was made by L. R. Wager in 1930 (Deer, 1967) during a boat journey undertaken by the British Arctic Air Route Expedition 1930-31. Wager (1934) showed that there are five centres, namely Kap Gustav Holm, Kialineq, Nualik, lgdlitarajik and Kangerdlugssuaq (fig. 348). During the Scoresby Sound Committee's Second East Greenland Expedition, Wager discovered a further centre, in the Lilloise Bjerge, east of Kangerdlugssuaq. Of the six centres only that at Kangerdlugssuaq is well known, largely because of the presence there of the Skaergaard intrusion (Wager & Deer, 1939; Wager & Brown, 1968). No further information beyond that of the original reconnaissance in 1934 has been added to the knowledge of the igneous rocks of the Kap Gustav Holm, Nualik and lgdlitarajik centres. The Kialineq centre, however, was reinvestigated by a party led by Dr. P. E. Brown during the British East Greenland Geological Expedition 1966, and some of the preliminary results of that work are included in this account. The Lilloise centre was later examined by Brown (1973) and the earlier view that it consisted of syenites including nepheline-bearing varieties was shown to be in error. The syenite debris on the moraine at the head of Wiedemann Fjord is now known to have been derived from the Borgtinde in trusion some 35 km to the north of the Lilloise mass.