GEOL30040 Sedimentary Environments

Academic Year 2023/2024

This module addresses the sedimentology of the main Earth surface environments ranging from terrestrial settings all the way to the deep-sea with a focus on the facies and depositional systems they leave. The module builds on the process understanding delivered in GEOL20190 illustrating the distinctive record of the main clastic settings and considering how and why surface environments change and how we read this record. Practical exercises illustrate some of the key tools used to reconstruct both Recent and ancient environments, including palaeoflow analysis, provenance studies and sediment routing, graphic logging techniques, satellite imagary and seismic geomorphology. The module also covers volcanic eruption mechanisms as eruptions significantly impact surface environments and represent a critical geohazard. The key features of lava flows, fall deposits, pyroclastic fall and density currents and lahars are covered and the implications for reconstructing eruption history and hazard potential assessed.

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Curricular information is subject to change

Learning Outcomes:

1) Relate facies associations, sedimentary structures and bed geometries to processes of deposition for the main Earth surface environments;
2) Collect and interpret graphic logs from outcrops and cores;
3) Measure, process, display and interpret palaeocurrent information;
4) Use and combine datasets of different scales - from seafloor bathymetry and seismic to core;
5) Understand the eruption and dispersal of lava flows and volcaniclastic sediment around active volcanoes.

Indicative Module Content:

Lectures

Lecture 1 (Kara English) Introduction: facies and depositional environments
Facies concept and Walther's Law. Facies associations and facies successions. Depositional system concept illustrated by a moving shoreline. Rates of accommodation creation and sediment supply - two key variables controlling environmental change.

Lecture 2 (Kara English) Alluvial fans: interface between sedimentation, tectonics and climate
Alluvial fan geometry, gradient and range of fan types. Controls on fan size. Deposits of alluvial fans and links to gradient/size. Ancient fanglomerates and vertical cycles. Fans and the geometry of basin margin faults. Climatic controls on fan behaviour.

Lecture 3 (Kara English) Desert sedimentation
Controls on desert conditions. Hot and cold deserts. Recap on aeolian stratification types and bedforms. Dune internal structure and interdune deposits. Impact of changing water table. Bounding surfaces and supersurfaces. Erg centre vs. erg margin. Aeolian stratigraphy.

Lecture 4 (Kara English) Lakes and lacustrine deposits
Types of lake. Lake depositional systems. Impact of climate and changing lake level. Extracting climate signals from lake deposits.

Lecture 5 (Kara English) Rivers: channel patterns and deposits
River channel patterns and channel associations. Controls on channel patterns. Gravelly and sandy braid bars and braided stream deposits. Deposition in sinuous/meandering channels. Distinguishing ancient channel patterns.

Lecture 6 (Kara English) Flooding, floodplains and alluvial stratigraphy
Floodplain processes. How do channels migrate? Avulsion. Palaeosoils. Multilateral and multistorey sandbodies. Alluvial architecture. Rivers on tilting surfaces. Incision and response to changing base-level.

Lecture 7 (Sam Kelley) Ice sheets and glacial deposition
Processes of entrainment, transport and deposition in glacial systems, with an emphasis on sequence stratigraphy and landform development.

Lecture 8: (Kara English) Estuaries
Estuaries 'rising' significance. Types of modern estuary. Wave- and tide-dominated end members and their internal stratigraphy. Gironde estuary - context in relation to Holcene sea level changes. Ancient examples of wave- and tide-dominated estuaries.

Lecture 9: (Kara English) Linear clastic shorelines
Beach processes. Transgressive barrier islands and their stratigraphic record. Strandplains and cheniers. Lowstand detached shorelines, forced regressions and ravinement.

Lecture 10 (Kara English) Deltas
Stratigraphic record of delta progradation. Delta front instability, growth faulting and mud diapirs. Delta asymmetry. Impact of sea level change on delta evolution and vulnerability. Location and variability of modern deltas and coastal (apalic) landforms. Delta classification and terminology. Outflow dynamics and mouth bar progradation. Delta front instability. Delta top processes. Delta lobe switching.

Lecture 11 (Kara English) Storm-dominated shelf systems
Wave-dominated shelf sandstones: key structures and lateral trends. Models for storm-influenced sedimentation. Trangressive vs. prograding shelves. Ichnofabrics.

Lecture 12 (Kara English) Submarine slopes and clinoforms
Classification of clinoforms. Recap on sediment gravity flows. Flow efficiency concept. Mass transport deposits and their impact. Canyons and channelised turbidity currents. Ponded currents and impact of slope topography (stepped slopes).

Lecture 13 (Kara English) Deep sea fan deposits and models
Development of deep sea fan models. Variable fan scale and character. Impact of grain size and feeder system. Controls on deep-water deposition. Models for fan growth and decay and deep-water stratigraphy.

Lecture 14 (Claire Harnett) Introduction to volcanic processes
Volcanic settings, eruption types and their resultant stratigraphy. General features of magamatic and hydrovolcanic eruptions, and introduction to different types of volcanic rocks. Main magma properties – viscosity, volatiles, fragmentation.

Lecture 15 (Claire Harnett) Effusive eruptions: lava flows
Basic magma rheology. Sites of effusive eruption – overview and terminology linked to fissure eruptions, A’a flows, pahoehoe, block flows, flood basalts. Pahoehoe-a’a transition. Lava domes. Rhyolite flows. Flow thicknesses and the construction of lava levees.

Lecture 16 (Claire Harnett) Eruption columns and fall deposits
Introduction to different types of pyroclastic deposit and classification of their ejecta – difference between ballistic tephra and tephra fall, e.g. bombs, accretionary lapilli, ash, pumice, Pele’s hair, ash. Geometry of eruption columns and how this affects tephra fallout and dispersal, including effect of wind and construction of isopleth/isopach maps. Types of tephra produced for different styles of eruption – examples from field deposits.

Lecture 17 (Claire Harnett) Pyroclastic density currents
Origin of pyroclastic density currents: directed blast, lava dome collapse, boiling over, eruption column collapse. Mt. St. Helens case study. Mechanisms of flow emplacement and structure of resultant PDC. Overview of PDC deposits: block and ash flow, unwelded and welded ignimbrites. Post-emplacement processes, e.g. rheomorphic deformation, devitrification. Pyroclastic surges: low concentration base, ground and ash cloud surges.

Lecture 18 (Claire Harnett) Debris avalanches and lahars
Lahars: genesis, flow behaviour (mechanical, geological), resultant deposits. Depositional processes associated with lahars, e.g. erosion, bulking, downstream dilution, resultant grain-size distributions. Debris avalanches and volcanic gravitational deformation, e.g. sector collapse, flank collapse, particularly on island arcs. Spreading and sagging, triggers of volcanic landslides, structure of deposits.

Lecture 19 & 20 - Student Presentations



Practicals

Practical 1 Walther's Law and sedimentary structures
Using sedimentary structures to reconstruct depositional processes and way-up.

Practical 2 Structural Analysis and Paleoflow
Re-orientation of cross-bed data and recontruction of original environments of deposition.

Practical 3 Re-orientation of palaeocurrent data using Stereonets
Re-orientation of cross-bed data and recontruction of original environments of deposition.

Practical 4 Graphic logging techniques
Core logging techniques and depositional interpretation using a short Brent delta core from the northern North Sea.

Practical 5 Environmental change from space
Interpretation of depositional history using GoogleEarth imagery from Coco River Delta, Honduras.

Practical 6 Seismic geomorphology in the deep ocean
Amazon fan evolution inferred from 3D seismic dataset on the Amazon slope.

Practical 7 Volcanic rocks in hand specimen - lava flows
Hand specimens of acid and basic lava flows illustrating characteristic features.

Practical 8 Bishops Tuff
Hand specimens and thin sections of an unwelded to welded pyroclastic flow deposit - Bishops Tuff, considering the stratigraphy of a typical PDC.

Practical 9 Volcanic hazards




Field trip to Hook Head, Wexford
A one-day field excursion to look at the products of the Devonian-Carboniferous transgression in south Wexford

Student Effort Hours: 
Student Effort Type Hours
Lectures

20

Practical

20

Field Trip/External Visits

8

Autonomous Student Learning

60

Total

108

Approaches to Teaching and Learning:
The module comprises lectures and related problem-based practical sessions in which participants are exposed to the main tools used to reconstruct past surface environments and to understand the drivers causing environmental change.
Students will be required to present a project at end of term. 
Requirements, Exclusions and Recommendations

Not applicable to this module.


Module Requisites and Incompatibles
Pre-requisite:
GEOL20250 - Crystals to Sedimentary Rocks

Additional Information:
One of the pre-requisites listed.


 
Assessment Strategy  
Description Timing Open Book Exam Component Scale Must Pass Component % of Final Grade In Module Component Repeat Offered
Class Test: Practical test Week 12 n/a Standard conversion grade scale 40% No

25

No
Continuous Assessment: Practical exercises and student presentation Throughout the Trimester n/a Standard conversion grade scale 40% No

35

No
Examination: Written examination testing all module components 2 hour End of Trimester Exam No Standard conversion grade scale 40% No

40

No

Carry forward of passed components
Yes
 
Resit In Terminal Exam
Spring Yes - 2 Hour
Please see Student Jargon Buster for more information about remediation types and timing. 
Feedback Strategy/Strategies

• Feedback individually to students, on an activity or draft prior to summative assessment
• Feedback individually to students, post-assessment
• Group/class feedback, post-assessment

How will my Feedback be Delivered?

Feedback given throughout module on practical assignments and post-assessment on an individual basis. In-trimester clinics on a weekly basis.

‘Sedimentary Environments: Processes, Facies and Stratigraphy’ by H.G. Reading, 1996. 3rd edition. Blackwell Science.
‘Earth Surface Processes, Landforms and Sediment deposits’ by Bridge, J. and Demicco, R., 2008. Cambridge University Press.
‘Sedimentology Geology’ by D.R. Prothero & F. Schwab, 1996. Freeman & Co., New York.
‘Sedimentology and Stratigraphy’ by G. Nichols, 1999. Blackwell Science Ltd, Oxford.
‘Sedimentology and Sedimentary Basins’ by M.R. Leeder, 2011. 3rd edition. Wiley-Blackwell Ltd.
‘Facies models: response to sea level change’ by R.G. Walker & N.P. James, 1992. Geological Association of Canada.
‘Volcanoes’ by Francis, P. and Oppenheimer, C. 2004. Oxford University Press, 2nd edition.
‘Volcanoes – global perspectives’ J.P. Lockwood and R.W. Hazlett.2010. Wiley-Blackwell. .
Fundamentals of physical volcanology’ . E.A. Parfitt & L. Wilson. 2008. Blackwell Publishing.
Name Role
Assoc Professor Claire Harnett Lecturer / Co-Lecturer
Dr Sam Kelley Lecturer / Co-Lecturer
Rioko Moscardini Tutor