Abstract

INTRODUCTION

The origin of green rock complexes in the Adirondacks, their interrelations, and their relations to other Precambrian rock types are obscure. These green rocks have been called syenites (Smyth, 1897), older granites (Buddington, 1939), and charnockites (Berry and Walton, 1962). Buddington (1939), after working in the northern Adirondacks, thought that anorthosite and two generations of granite intruded the Grenville sequence of sediments. De Waard and Walton (1967), after working in the southern Adirondacks, thought that the sequence of sediments was deposited on meta-anorthosite and charnockitic gneiss. Buddington thought that all granitic and charnockitic rocks in the Adirondacks were intruded. De Waard and Walton thought that some belonged to the basement complex upon which the Grenville sediments were deposited, some were initially deposited as Grenville sediments, and some were produced by local melting. The diverse characters and occurrences of granitic and charnockitic gneisses in the Adirondacks show that these rocks formed by several processes.

Recent field studies have investigated two green rock complexes: the Tupper Complex (Crosby, 1968; Davis, 1969; Seifert, 1978) and the Diana Complex (Hargraves, 1969; Wiener, 1979). These studies have generally supported Buddington's conclusions. The Stark Complex is the only green rock complex in the northern Adirondacks that has not been examined since de Waard and Walton published their interpretation of Adirondack geology. Rocks around Jennings Mountain, Lyon Mountain, Taylor Pond, and Loon Lake and between Lake Titus and Blue Mountain are part of the Stark Complex. This paper presents the results of a study on the Stark Complex around Dexter Lake and relates that complex to other green rock complexes, the Grenville sequence, and granitic gneisses that Buddington (1939, p. 135–149) labeled the younger granites.

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