Ichnofabrics

1. Sedimentology 2/1
Image log & dipmeter
analysis course
Ichnofabrics – recognition
& interpretation

2. Sedimentology 2/2
“Those aspects of the sediment's texture and internal
structure that arise from bioturbation and bio-erosion at all
scales" (Ekdale & Bromley 1983).
“A record of the primary sedimentary conditions, original
animal community, and subsequent history of one or more
phases of biogenic activity” (Taylor & Goldring 1993).
Definitions

3. Sedimentology 2/3
_ 3.41
_ 1.64
_ 2.35
_ 0.21
_ 0.75
_ 2.81
_ 1.81
Log K
Permeability map
Thin section
Core
Microporous nodular limestones

4. Sedimentology 2/4
•Degree of bioturbation
•Ichnofauna
•Diversity
•Burrow organisation
•Tiering
•Lithology
•Sedimentary structures
Observations

5. Sedimentology 2/5

6. Sedimentology 2/6
Trace fossils Environment
Shoreface Shelf
Tidal Foreshore Upper Middle Lower Inner Outer
Arenicolites x x x x x
Asterosoma x x
Bergaueria x x x x x
Chondrites x x
Conichnus x x x x x
Diplocraterion x x x
Escape structures x x x x x x
Gyrolithes x x
Lockeia x x
Macaronichnus x x x x
Monocraterion x x
Muensteria x x x
Ophiomorpha x x x x
Palaeophycus x x x x x
Phycosiphon x x x
Planolites x x x x x x
Rhizocorallium x x
Roots
Rosselia x x x
Scolicia x x x
Siphonites x x x
Skolithos x x x x x x x
Taenidium
Teichichnus x x x
Terebellina x x x
Thalassinoides x x x x x x
Trichichnus x x x

7. Sedimentology 2/7
Cross-beds, clay-draped
foresets, bidirectional,
thick bottomsets, flaser
bedded.
Variable bioturbation,
moderate diversity.
Planolites
Macaronichnus
Ophiomorpha
Thalassinoides
Palaeophycus
Tidal channel

8. Sedimentology 2/8
Cross-bedded to
parallel-laminated
sands.
Variable bioturbation,
moderate diversity.
Ophiomorpha
Scolicia
Planolites
Macaronichnus
Upper shoreface

9. Sedimentology 2/9
Fair weather deposits;
sandy heterolithics.
Storm deposits, HCS-SCS
sands.
Intensely bioturbated, high
diversity.
Phycosiphon, Rhizocorallium
Teichichnus, Palaeophycus
Sparsely bioturbated, low
diversity.
Ophiomorpha
Lower shoreface

10. Sedimentology 2/10
Muddy heterolithics.
Intensely bioturbated,
high diversity.
Phycosiphon
Teichichnus
Planolites
Chondrites
Rhizocorallium
Inner shelf

11. Sedimentology 2/11
Bioturbated mudstone.
Laminated mudstone.
Sparsely bioturbated, low
diversity.
Phycosiphon
Thalassinoides
Intensely bioturbated,
moderate diversity.
Phycosiphon
Chondrites
Planolites
Outer shelf

12. Sedimentology 2/12
Resolution of bioturbation fabrics

13. Sedimentology 2/13
Fabric index - determined via flash cards
Mottling and loss of fabric in this example is due to
bioturbation - hence we have a bioturbation index
Fabric index

14. Sedimentology 2/14
Fabric Analysis adds an extra
dimension to lithofacies description if
it can include a quantitative descriptor.
E.g. Well laminated versus poorly
laminated, and stages in-between.
Fabric index from dipmeter curve activity