Previous   |    Close   |    Next

Table T2. Summary of observed lithofacies, Site U1417.

Main facies Subfacies Facies Description Marine microfossils Lithostratigraphic
unit
Tentative depositional
environment/diagenesis
Mud   Massive mud with lonestones F1a Dark gray to (dark) greenish gray; Bioturbated (none to heavy); Occasionally calcareous bearing; Occasionally diatom rich/bearing; Lonestones of granule and pebble sizes occur in varying amounts; Occasional color banding and black mottles; Occasional sand pods; Interbedded with Facies F1b, F2a, F2b, F3a, F3b, F3c, F4a, F4b, F4c, F4d, F5a, F5b, F5c, F6, F7, and F8. Variable IA, IB, II, III, IV, VA, VB, VC, VD, VE, VG, VI Suspension fall-out, ice rafting, or sediment gravity flows
Massive mud without lonestones F1b Dark gray to (dark) greenish gray; Bioturbated (none to heavy); Occasional Zoophycos burrows; Occasionally calcareous bearing; Occasionally diatom rich/bearing; Occasional color banding and black mottles; Occasional silt pods/lenses; Interbedded with Facies F1a, F2a, F2b, F3a, F3c, F4a, F4c, F4d, F5a, F5b, F5c, F6, and F7. Diatoms may occur IA, IB, II, IV, VA, VB, VC, VD, VE, VG, VI Suspension fall-out, ice rafting, or sediment gravity flows
Silt   Silt F2a Dark gray to greenish gray; Often interbedded with mud; Sharp to gradational upper and lower contacts; Diatoms may occur; Interbedded with Facies F1a, F1b, F2b, F3a, F4d, F5a, F5b, F5c, F6, and F7. Diatoms may occur IA, IB, II, VE, VF, VG, VH, VI Sediment gravity flows
Interbedded silt and mud F2b Dark gray to greenish gray; Facies thickness 2 to 360 cm; Occasional color banding; None to moderate bioturbation; Occasionally with terrestrial organic components; Interbedded with Facies F1a, F1b, F2a, F3a, F4d, F4e, F4f, F6, and F8. Not documented IA, II, VE Mud: suspension fall-out from surface water plumes and from sediment gravity flows Silt: sediment gravity flows
Sand     Very fine to coarse sand F3a Dark gray to gray; Bed thickness from 1 to 5 cm, occasionally thicker; Massive and normal grading; Sharp and frequently erosional lower contacts; Gradational and sharp upper contacts; Composition includes quartz and feldspar; Interbedded with Facies F1a, F1b, F2a, F2b, F4b, F4d, F5a, F5b, F5c, and F6. Not documented IA, IB, II, IV, VA, VB, VC, VE, VG, VI Sediment gravity flows
Medium to coarse sand F3b Dark gray to gray; Bed thickness up to 40 cm; Rip-up clasts common; Plant debris, organic matter, and diatoms may occur; Sharp bases and sharp to gradational upper contacts; Interbedded with Facies F1a and F4b. Not documented VA Sediment gravity flows
Interbedded sand and mud F3c Dark gray to dark greenish gray; Facies thickness 7–710 cm; Partly diatom bearing; None to moderate bioturbation; Partly with volcanic ash; Occasional color banding; Lonestones may occur; Interbedded with Facies F1a, F1b, F5a, F5b, F5b, F6, and F7. Diatoms may occur IB, II, VA Suspension fall-out from surface water plumes (mud), ice rafting (mud, sand, lonestones), and sediment gravity flows (sand, mud)
Diamict       Muddy diamict F4a Dark gray; Muddy matrix; Clast concentration variable; Thin bedded or pods; Lower contacts are gradational; Upper contacts are sharp and defined by concentration of clasts; Granule and small pebble clasts are commonly subangular to subrounded; Interbedded with Facies F1a and F5c Not documented IB, III Suspension settling and ice rafting (mainly by icebergs)
Muddy and sandy diamict with lithic and mud clasts and/or terrigenous organic components F4b Dark gray; Mud to sand matrix; Bed thickness up to 40 cm; Sharp upper and lower contacts; Lithic and mud clasts up to 3 cm; Occasional plant debris and terrestrial organic components (coal?); Interbedded with Facies F1a, F1b, F3a, F3b, F5a, F5b, F7, and F8 (in disturbed sequence). Diatoms (partly freshwater) VA, VC, VD, VE, VF, VG, VI Sediment gravity flows
Breccia F4c Dark gray matrix; Sandy mud matrix; Bed thickness typically 100 cm; Sharp erosive lower contacts; Gradational upper contacts; Most often clasts of indurated diatom ooze; Interbedded with Facies F1a and 5a. Not documented VF Sediment gravity flows (e.g., slump)
Interbedded mud and diamict F4d Dark gray to greenish gray; Occasional color banding and parallel lamination; None to moderate bioturbation; Occasionally calcareous bearing; Interbedded with Facies F1a, F1b, F2a, F2b, F3a, F4e, F5b, F5c, and F7. Not documented III, VC, VE Suspension settling and ice rafting (icebergs and/or sea ice)
Diatom ooze   F5a Greenish gray; 20 cm to 1.5 m; Bioturbation (including Zoophycos burrows); Sharp to gradational upper and lower contacts; Interbedded with Facies F1a, F1b, F2a, F3a, F3c, F4b, F4c, F5b, and F6. Diatoms and other biosiliceous material; occasional carbonate (foraminifers and coccolithophores) IA, IB, II, VA, VB, VD, VF, VH, VJ High-productivity environment and/or low terrigenous input and/or better preservation
Biosiliceous ooze; biosiliceous-rich/bearing mud and sand; mud with diatoms/biosilica   F5b (Very) dark gray to (dark) greenish gray and brown; Facies thickness 2–445 cm; Mostly mud, rarely sand; Diatom and biosiliceous rich/bearing; Lonestones are absent or present; Occasional color banding; Partly mottled; Occasionally laminated; None to heavy bioturbation; Interbedded with Facies F1a, F1b, F2a, F3a, F3c, F4b, F5a, F5c, F6, F7, and F8. Diatoms and other biosiliceous material IA, IB, II, IV, VA, VB, VC, VD, VE, VH, VI High-productivity environment and/or low terrigenous input and/or better preservation
Calcareous/carbonate-bearing/rich mud, silt, sand, diamict, and/or diatom ooze   F5c (Very) dark gray to greenish gray; Facies thickness 3–316 cm; Occasionally with volcanic ash; None to heavy bioturbation; Occasional color banding and lamination; Interbedded with Facies F1a, F1b, F2a, F3a, F4a, F4b, F5b, and F8. Foraminifers; occasionally diatoms II, III, IV, VB, VE, VI Temporarily increased productivity and/or reduced suspension settling and/or better preservation
Ash Volcanic ash F6 Usually gray to brown; Bed thickness typically 1–5 cm; Sharp lower contacts; Sharp to gradational upper contacts; Primarily vitric shards (glass); Some intervals affected by bioturbation; Often interbedded with Facies F1a, F1b, F2a, F3a, F3c, F5a, and F5b. Not documented IA, IB, II, VA Suspension settling after subaerial eruptions
Volcaniclastic mud, sand, diamict and/or ooze   F7 Usually grayish, greenish, or brownish; Bed thickness typically 1–5 cm; Sharp and frequently erosive lower contacts; Gradational to sharp upper contacts; Primarily vitric shards (glass); Some intervals affected by bioturbation; Often interbedded with Facies F1a, F1b, F2a, F3c, F4d, F5b, and F7. Diatoms IA, IB, II, III, IV Volcanic detritus either bioturbated or reworked/redeposited by sediment gravity flows
Rock   F8 Siltstone with carbonate cement; Often interbedded with Facies F1a, F2b, F4b, F5b, and F5c.   VC, VE, VH In situ carbonate sedimentation

Previous   |    Close   |    Next   |    Top of page