The Hawaiian-Emporer volcanic chain, part 1, geologic evolution

Abstract

Chaper One (1), Volcanism in Hawaii. Stratigraphy is an important tool for understanding the geologic history of the volcanoes of the Hawaiian Islands, providing a framework for much information from other geologic and related fields. Three major eruptive stages in a Hawaiian volcano's life-shield stage (tholeiitic), postshield stage (alkalic), and rejuvenated stage (alkalic) - have generally provided a basis for dividing the volcanic rocks into atratigraphic units. Such units are basic to stratigraphy, and suitable nomenclature for them helps promote unambiguous scientific communication regarding the spatial and temporal relations of rocks. The stratigraphic nomenclature of the Hawaiian Islands is herein reviewed and updated to reflect current scientific needs and to be consistent with the most recent (1983) North American Stratigraphic Code. The major divisions of volcanic rocks on each island formerly called "Volcanic Series" are all considered to be of formational rank and renamed accordingly. Their names reflect either a predominant commonly accepted lithologic type (such as "Basalt") or the variety of volcanic lithologies in the unit (those units are called "Volcanics"). Only those subdivisions of the major units that are currently considered to be useful as formally named units of member or lesser rank are retained; others are considered to be informal. Principal and other reference localities are designated for those well-established units for which a type locality was not previously specified. We give in tabular form a brief summary of each stratigraphic unit, including its lithology, occurrence, thickness, type and reference localities, stratigraphic relations, age, and any stratigraphic changes made herein.