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Table T1. Glossary of common geological terms used to describe basement rocks, Expedition 329.

Term Explanation
Breccia (Br)  
Type of breccia Hydrothermal (Bh), magmatic (Bm), tectonic (Bc)
Volume percent Percent clasts vs. bulk rock
Size range Maximum–minimum average size
Shape Angular, subangular, subrounded, rounded, etc.
Composition Monomictic, polymictic
Structure Internal crushing, veining, fracturing, etc.; preferred orientation
Alteration Alteration halos in the clasts
Sorting Well sorted, moderately sorted, poorly sorted
Volume percent Percent matrix vs. bulk rock
Grain size Coarse, medium, fine
Composition Lithology and/or mineralogy compared with clasts
Structure Veining, fracturing, preferred orientation, shearing
Alteration Alteration in the matrix
Volume percent Percent cement vs. bulk rock
Composition Mineralogy
Veins (V)  
Vein type Magmatic/late magmatic (Vm), hydrothermal (Vh)
Orientation of vein Vertical, horizontal
Depth of vein Interval in the core
Morphology Planar (Pl), curved (Cv), irregular (Ir), sigmoidal (Sg), stepped (St), T-shaped (T), Y-shaped (Y), splayed (S)
Vein array geometry Conjugate, network, en echelon, anastomosing, riedel
Vein density (N/10 cm) No vein, slight, moderate, high, complete
Fabric of the filling minerals Fibrous (Fb), vermicular (Vr), blocky (Bl)
Vein mineralogy Carbonate, quartz, Fe oxide, celadonite, etc.
Average width and length Measured in millimeters
Joints (J)  
Orientation of joint Direction of joint
Depth of joint Interval within the core
Morphology Planar (Pl), curvilinear (Cv), anastomosing (An), T-shaped (T), Y-shaped (Y), splayed (Spl), stepped (St)
Joint array Conjugate, network, en echelon
Joint density Number of joints in an ligneous unit or per core/site
Faults (F)  
Orientation of fault Direction of fault
Depth of fault Interval within the core
Magnitude of the apparent offset Measured offset (on the cut face of the core and side wall)
Apparent sense of shear Dextral (dx), sinistral (sx), reversed (r), normal (n)
Crosscutting relationships Relative timing from one feature to another
Average thickness of fault zone Fault zone thickness measured in millimeters
Occurrence of alteration halos Halos associated with fluid flow through the fault zone
Occurrence and type of fault rocks Rocks formed by faulting (e.g., cataclasite)
Composite vein Compositionally and texturally zoned vein containing different mineral assemblages that may or may not represent different generations.
Fabric Relative orientation of parts of a rock mass. Preferred linear orientation of part of a rock is termed linear fabric, preferred planar orientation is termed planar fabric, and lack of a preferred orientation is referred to as random fabric.
Fault Fractures with kinematic evidence for shear displacement across the discontinuity or with an associated cataclasite.
Foliation Any repetitively occurring penetrative planar feature in a rock body.
Joint Fractures in which the two sides show no differential displacement (relative to the naked eye or 10× hand lens) and have no filling material.
Shear vein Obliquely opening veins with minor shear displacement, filled with slickenfibers or overlapping fibers.
Texture Relative size, shape, and spatial interrelationship between grains and internal features of grains in a rock.
Vein Extensional or oblique open fractures filled with epigenic minerals.

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