| Major lithologic names are defined as combinations of the following four major modifiers (grain types), using Figure F1: |
|---|
| Siliciclastics: |
| Crystalline grains and detrital aggregates |
| Quartz, feldspars, clay minerals, heavy minerals, rock fragments, opaque minerals, and glauconite |
| Modifier definition: Siliciclastic grains are classified in their size such as sand (2 mm-63 µm), silt (63 µm-4 µm), and clay (<4 µm) according to Wentworth (1922). Siliciclastic modifiers are defined using Figure F2. |
| Volcaniclastics: |
| Amorphous grains of volcanic origin and their altered products |
| Glass shards, pumice, scoria, and palagonite |
| Modifier definition: Volcaniclastic grains are classified in three grain-size classes as ash (<2 mm), lapilli (2-64 mm), and breccia (>64 mm). Volcaniclastic modifiers are defined using the most abundant size class. |
| Biogenics: |
| Remains of organisms with siliceous and calcareous hard parts. Microcrystalline carbonate and aggregates of unknown origin are also included. |
| Group 1 (siliceous) diatom, radiolarians, silicoflagellates, and sponge spicules |
| Group 1 (calcareous pelagic) foraminifers, and nannofossils |
| Group 2 (calcareous unknown) micrite |
| Group 2 (calcareous nonpelagic) some benthic foraminifers, bioclasts, and peloids |
| Modifier definition: |
| 1. Normalize each biogenic component to 100%. |
| 2. If the total of Group 1 grains is >50%, define a pelagic modifier with the >25% components of Group 1 in order of increasing abundance. If two or more components have equal amounts, then use a hyphen between the names rather than a space. Components of 10%-25% in Group 1 are treated as biogenic minor modifiers, while those of 10%-50% in Group 2 are treated as diagenetic minor modifiers. |
| 3. If the total of Group 2 grains is >50%, define a nonpelagic modifier using limestone classification scheme (Fig. F3 after Dunham [1962]). Components of 10%-50% in Group 1 are treated as biogenic minor modifiers. If two or more components in biogenic minor modifier have equal amounts, then use a hyphen between the names rather than a space. |
| Other minor modifiers (diagenetic): |
| Grains formed during postdepositional process. |
| Pyrite, dolomite, and zeolites. Microcrystalline carbonate and aggregates of unknown origin are included. |
| Modifier definition: Diagenetic grains are treated as a diagenetic minor modifier. |
| Diagenetic grains are treated as a diagenetic minor modifier. |
| Treatment of minor modifiers: |
| Biogenic minor modifiers and diagenetic minor modifiers <10% in bulk sediment are ignored. |
| Remaining biogenic minor modifiers are placed in order of increasing abundance just before pelagic modifier or nonpelagic modifier using X-, Y-, Z-bearing style (see Fig. F4 for example). If two or more components in biogenic minor modifiers have equal amounts, then use a hyphen between the names rather than a space. |
| Diagenetic minor modifiers are placed in order of decreasing abundance after major lithologic name using Z, Y, and X style. If two or more components with diagenetic minor modifiers have equal amounts, then use a hyphen between the names rather than a space |
| If "-bearing" occurs twice in the lithologic name, the first one is removed, such as X Y-bearing Z; X-bearing Y-bearing Z style is never used. |