The Bedrock Nomenclature of New Brunswick includes detailed descriptions of all lithostratigraphic and intrusive units currently used by the Geological Surveys Branch to denote rock units in the Province. These units are included solely on the basis that they are necessary to give a full description of the bedrock geology of New Brunswick. No attempt has been made to classify the units into formal and informal categories as defined in the North American Stratigraphic Code (1983).
The following subheadings are used for each entry: Unit Name; Age; Author; Type Locality; Lithology; Thickness and Distribution; Relations to Other Units; Age Justification; History; and References.
The hierarchical classification adopted for the “Unit Name” follows that specified in the North American Stratigraphic Code (1983). In naming lithostratigraphic units, a geographic term including its generic component (e.g., River, Mountain, etc.) is followed by the word Group or Formation. Supergroup is used to designate the tectonically juxtaposed groups within the Bathurst Mining Camp
Entries are presented in alphabetical order and include both formations and groups. A brief description of constituent formations is given under the entry for each Group. Detailed descriptions of each Formation; the Group assignment for the Formation is shown in parentheses, e.g.Turnbull Mountain Formation (Tetagouche Group). Description of a Member is included only under its respective Formation.
The name of an intrusive unit includes a geographic component followed by a simple compositional term (i.e., Granite, Gabbro, etc.). A collection of intrusive units are included either in a Batholith (in the case of traditional usage) or in a Suite (for newly introduced units). The regionally significant Ministers Island Dyke and Caraquet Dyke are also described.
“Age” of a rock unit uses geochronologic (e.g., Early, Middle, Late) rather than chronostratigraphic prefixes (e.g., Lower, Middle, Upper) so as to apply consistently to both stratigraphic and intrusive units. Age information is generally specified at the period level, e.g., the Turnbull Mountain Formation is cited as Early Ordovician.
Under “Author” are included the names of those responsible for introducing and revising the nomenclature, along with the year(s) in which the work was done. Terms may have originally been introduced in scientific journals, government reports, guidebooks or theses, etc., and are included if they are now widely accepted into the geologic literature.
The “Type Locality” is described in detail and includes the reference number of the National Topographic System (NTS) map area. The Type Locality is a representative section of exposure at, or near to, the geographical feature attached to the Unit Name. Additional sites containing more complete or accessible sections may be listed as reference sections. Naming of many of the stratigraphic units in New Brunswick took place long before the introduction of a formal code; type localities in these instances were designated retroactively using original publications as a guide.
The “Lithology” section gives a brief description of all rock types found within a unit, including both vertical and lateral variations. An interpretation of the depositional environment may also be given.
The “Thickness and Distribution” section presents details on variations in thickness of lithostratigraphic units, with available measurements given in metres. Distribution includes regional extent of the lithostratigrahic or intrusive unit with areas identified by NTS number. Geographic designations may in some cases be derived from type sections located in adjacent provinces or the State of Maine.
“Relations to Other Units” primarily outlines the nature of the contacts with underlying and overlying units. This includes information on whether the boundaries are conformable, disconformable, unconformable, or tectonic in character. Suggested correlations with possible laterally equivalent units may also be given.
“Age Justification” includes paleontological data from lithostratigraphic units that may provide ages at the period, epoch, or stage level depending on the constraints inherent in the fossil assemblage. If unfossiliferous, the age of a unit may be inferred from its stratigraphic position with respect to beds of known age, or determined by radiometric dating. Ages of intrusive units are based on cross-cutting relationships, radiometric determinations, and by correlation with lithologically similar units of known ages.
The “History” section details first usage of the term, subsequent revisions in nomenclature or interpretation of geological relationships, and relevant work reported in other papers.
The “References” section provides authors and dates of all publications that are cited under a particular entry. All references are given in full in the Appendix.
The initials of the compiling author(s) for each bedrock unit listed are given below each entry (e.g., LRF = Les Fyffe; RAW = Reg Wilson; SCJ = Susan Johnson; SRM = Steve McCutcheon).
Government of New Brunswick