Tidal Depositional Environments & Stratigraphy | GEO GIRL

Tidal depositional environments are regions along ocean margins where tides strongly influence the deposition of sediment and formation of sedimentary structures that get preserved in the rock record over geologic time. In this video, I cover tidal processes and deposition, as well as the sedimentary structures and stratigraphy formed by tides, with both modern and ancient examples of tidal environments and the structures that form in these systems. We start by discussing the difference between waves and tides and the difference in wave influence on sediment movement and deposition compared to tidal sediment transport and deposition. I then move on to the difference between spring and neap tides and the difference in the spring tide sediment load relative to the neap tide sediment transport and deposition which is much weaker than spring tides. I also go over tidal range in various regions of the world, where tides are the largest and where they are dirunal. Then we jump into tidal sedimentary structures, such as laminations, cyclic rhythmites, tidal dunes, compound ripple marks, lenticular, wavy, & flaser bedding, and the difference between flood and ebb deposition. Finally we go over the bedforms formed by tides, such as tidal flats, tidal deltas, tidal estuaries, tidal bars, etc. Lastly, I show the stratigraphic columns that we expect to see in rocks that were deposited in tide-dominated environments, as well as some trace fossils (ichnofacies) that may help you recognize tide depositional environment in the field.
References:
Depositional Sedimentary Environments: amzn.to/3sSXxKZ
Facies models 4: amzn.to/3sSXyyx
dx.doi.org/10.1007/978-94-007-...
doi.org/10.2110/jsr.2018.28
doi.org/10.1016/j.sedgeo.2012...
doi.org/10.1016/j.sedgeo.2012...
dx.doi.org/10.2110/pec.98.61.0095
dx.doi.org/10.2110/pec.03.76.0147
doi.org/10.1007/978-94-007-01...
dx.doi.org/10.3923/jas.2017.2...
www.researchgate.net/publicat...
www.researchgate.net/publicat...
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0:00 What affects tidal environments?
0:39 Tides vs. waves?
1:57 What causes tides?
2:45 Spring vs. neap tides
4:20 Tidal range
5:22 Where are tides the largest? Smallest?
5:47 Tidal deposition/laminae/rhythmites
7:45 Tidal sedimentary structures (flood vs. ebb tides)
11:09 Tidal dunes and ripples
13:42 Preserved tidal dune outcrop
14:20 Lenticular, wavy, & flaser bedding formed by tides
15:56 Tidal environments: tidal deltas
16:54 Tidal environments: tidal estuaries
18:38 Tidal environments: tidal flats
19:34 Tidal stratigraphy
20:19 Tidal dune stratigraphy
20:41 Tidal channel stratigraphy
21:16 Trace fossils in tidal depositional environments
Image sources:
doi.org/10.1007/978-94-007-01...
www.amazon.ca/Facies-Models-R...
smallpond.ca/jim/sand/migrati...
doi.org/10.2110/jsr.2018.28
www.researchgate.net/profile/...
www.slideshare.net/wwlittle/b...
www.researchgate.net/publicat...
www.marinebiotech.eu/wiki/Wave...
www.researchgate.net/publicat...
www.sepmstrata.org/page.aspx?p...
wessexcoastgeology.soton.ac.u...
www.researchgate.net/publicat...
www.researchgate.net/figure/R...
www.researchgate.net/publicat...
seddepseq.co.uk/depositional_e...
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