Spilitic Rocks in New Zealand

Abstract

Prior to a discovery made recently by the writer, of spilitic rocks at Great King Island, the largest member of the Three Kings group of islands, about 26 miles north-west of the north-west extremity of the mainland of New Zealand, such rocks had not previously been found in this latter country. Some account of the types represented at Great King Island may therefore be welcome, particularly since Gilluly's (1935) recent comprehensive paper has focused attention on spilites and their associations.

A historical survey of the pre-cretaceous geology of New Zealand

“…There has been very little work at even the simplest of levels on matching conglomerate pebbles with igneous outcrops. The conglomerate pebbles examined by Marshall (1904) at Nelson, Mackie (1935) and Watters (1952) in Southland, and Marwick (1946) and Bartrum (1935) in Auckland have not been satisfactorily matched with their sources, and we still await exhaustive studies of variation and alteration in large granitic bodies. Other workers have been too quick to seize on a source, forgetting the warning sounded by Bell, Webb, and Clarke (1907, p. 44); and repeated by Benson and Bartrum (1935, p. 109), and Reed (1958a) that even the oldest of New Zealand sediments have been derived from granites.…”

“…The schists have also been altered by the intrusion of pegmatite dikes, and finally changed by retrogressive metamorphism, perhaps during the Lower Cretaceous orogeny, a little after the intrusion of the peridotites. In 1935 (b, p. 348) Turner postponed the date of metamorphism till the Late Permian or first half of the Triassic, noting F. W. Hutton's assertion of unconformity between the Permian and Triassic, and the presence of schist and hornfels pebbles (Turner, 1938d, p. 161) in Mesozoic rocks (Bartrum, 1935;Mackie, 1936). The age of the original sediment was given as Lower Ordovician to perhaps Lake Paleozoic (Turner, 1938d).…”

Precambrian geology and magnetite deposits of the New Jersey highlands in Warren County, New Jersey

“…Correspondingly, the Green River Formation contains more sodium than potassium (Milton and Eugster, 1959)- Kinkel et al, 1956;Colernan and Peterman, 1975;and Brown et al, 1979), keratophyres (Gilluly, 1935? Bartrum, 1929, 1936Battey, 1955;Albers, 1959;Dickinson, 1962;and Brown et al, 1979)> and sodic gneisses of the Reading Prong (Drake, 1969;Bayley, 1941;Baker and Buddington, 1970;and Sims, 1958). …”

“…Keratophyres (Gilluly, 1935;Bartrum, 1929Bartrum, , 1936Battey, 1955;Albers, 1959;Dickinson, 19^2;Brown et al, 1979) Albite granites and plagiogranites (Kinkel et al, 1956;Coleman and Peterman, 1975;Brown et al, 1979) Argillites of the Lockatong Formation (Van Houten, 1965) Q AlhLte-oligoclase granites from the Reading Prong (Drake, 19^9;Baker and Buddington, 1970;Sims, 1958) Oligoclase-quartz gneisses from the Reading Prong (Drake, 19^9;Baker and Buddington, 1970;Sims, 1958) …”

Chemical Evolution of Geosynclinal Material

“…Other than tholeiitic basalt, the most common volcanic rocks associated with geosynclinal sediments are spilites and keratophyres. These presumably related rocks are common in the Paleozoic geosynclinal sections of Europe, as the basal volcanic rocks of island arc areas such as the Virgin Islands , and in other oceanic margin environments such as New Zealand (Bartrum, 1936). Spilites and keratophyres are reportedly absent in the early Precambrian (for example, see Glikson, 1970;Anhaeusser and others, 1969), but such negative evidence is not positive proof.…”