See:pseudochromatism
The influence of structural features on ore deposition, e.g., ore minerals
filling fractures. CF:stratigraphic control
See:dome
Drilling done specif. to obtain detailed information delineating the
location of folds, domes, faults, and other subsurface structural features
undiscernible by studying strata exposed at the surface.
CF:structure drilling
See:fabric
The branch of geology that deals with the form, arrangement, and internal
structure of the rocks, and esp. with the description, representation, and
analysis of structures, chiefly on a moderate to small scale. The subject
is similar to tectonics, but the latter is generally used for the broader
regional or historical phases. AGI
High point of a structure. See also:high
The load due to the structure itself as distinguished from the imposed
load. Crispin
A record of the breaks, fractures, faults, and physical properties of
rocks within a formation.
Low point of a structure. See also:low
The analysis of fabric on the thin-section or micro scale. It includes the
study of grain shapes and relationships (microstructure) and the study of
crystallographic preferred orientations. The transmission electron
microscope is also employed to examine the substructures of deformed
crystals. AGI
See:stripped plain
a. The vertical distance between stratigraphically equivalent points at
the crest of an anticline and in the trough of an adjacent syncline.
AGI
b. More generally, the difference in elevation between the highest and
lowest points of a bed or stratigraphic horizon in a given region.
AGI
Rolled steel sections or other fabricated members assembled to form
structural frames by riveting, welding, bolting, or a combination of all
three. Hammond
a. A local shelf or steplike flattening in otherwise uniformly dipping
strata, composed of a synclinal bend above and an anticlinal bend at a
lower level. AGI
b. A terracelike landform controlled by the structure of the underlying
rocks; esp. a terrace produced by the more rapid erosion of weaker strata
lying on more resistant rocks in a formation with horizontal bedding.
AGI
A valley that owes its origin or form to the underlying geologic
structure. AGI
See:phyllovitrinite
a. The parts or members of any building that carry the loads and transmit
them to the foundations. Structures in mining areas may suffer some
subsidence and are designed accordingly. Nelson
b. Geologically, the disposition of the rock formations; i.e., the broad
dips, folds, faults, and unconformities at depth. Nelson
c. In petrology, one of the larger features of a rock mass, like bedding,
flow banding, jointing, cleavage, and brecciation; also, the sum total of
such features. CF:texture
d. See:soil structure
A contour that portrays a structural surface such as a formation boundary
or a fault. Syn:subsurface contour
An ore shoot that is localized by geologic structure. Changes in strike
and dip of fissures are favorable sites for ore shoots.
a. Exploratory drilling to determine the geological structure with
reference to the coal or minerals sought. Rotary or diamond drilling is
usually employed to yield cores at key horizons. Nelson
b. A form of drilling practiced in the Lake Superior iron district to
sample soft iron formations by countercirculation-wash boring methods.
CF:structural drilling