Unravelling the tectonic and climatic controls on Upper Jurassic mass flow deposits in NE Scotland
Lead Research Organisation:
The Open University
Department Name: Environment, Earth & Ecosystems
Abstract
The catastrophic failure of sediment accumulations on inclined surfaces produces some of the most visually dramatic of all sedimentary deposits. These deposits also present a number of scientific challenges including understanding the variable sedimentation rates, lateral changes, depositional processes and controls on sedimentation. An understanding of marine mass flow deposits is important because as well as presenting engineering challenges they form both reservoir and source rocks for hydrocarbons.
This project will examine the spectacular Kimmeridgian to Tithonian (Upper Jurassic) mass flow deposits that are well exposed along the coast in NE Scotland [1, 2, 3]. These rocks were deposited in the sea adjacent to the Helmsdale Fault system which was active during the Jurassic. Unusually, this mass flow system was active for over 8 Ma of Earth history and contains a spectrum of mass flow deposits from rock fall breccias, debris flows and homogenized sandstones to turbidites. These exposures thus provide a natural laboratory to consider the external controls on mass flow deposits over a long time period.
Preliminary sequence stratigraphic results suggest that whilst tectonics influenced the sediment supply, local distribution of the deposits and the long term cyclicity; the deposits can be grouped into depositional sequence cycles that are the same age as hemipelagic depositional sequences in Dorset [2, 4] and elsewhere implying a climatic control. Furthermore proven Milankovitch cycles in the Dorset [4] succession demonstrate that there is a strong climatic control at this time. A working hypothesis is that eustatic sea-level fall caused sediment instability resulting in higher energy and coarser-grained mass flow deposits, whereas eustatic sea-level rise resulted in lower energy mass flow deposits such as turbidites.
Upper image: Part of the spectacular mass flow deposits near Helmsdale that will be the focus of this study.
Lower image: Typical foreshore and cliff exposures in the study area.
The main objectives of this project are to:
1. Construct graphic logs and maps to record the nature of the deposits in time and space.
2. Complete palynological analysis of the mudrocks, integrate data with published ammonite biostratigraphy and develop biostratigraphic timescales for extra regional correlation.
3. Obtain a qualitative estimate of changes in weathering rate and transportation using palynomorph abundances and preservation respectively.
4. Construct a sequence stratigraphic interpretation of the deposits and use this to critically assess the relative role of tectonics and climate on the sediment packaging by comparison with sections elsewhere.
This project will examine the spectacular Kimmeridgian to Tithonian (Upper Jurassic) mass flow deposits that are well exposed along the coast in NE Scotland [1, 2, 3]. These rocks were deposited in the sea adjacent to the Helmsdale Fault system which was active during the Jurassic. Unusually, this mass flow system was active for over 8 Ma of Earth history and contains a spectrum of mass flow deposits from rock fall breccias, debris flows and homogenized sandstones to turbidites. These exposures thus provide a natural laboratory to consider the external controls on mass flow deposits over a long time period.
Preliminary sequence stratigraphic results suggest that whilst tectonics influenced the sediment supply, local distribution of the deposits and the long term cyclicity; the deposits can be grouped into depositional sequence cycles that are the same age as hemipelagic depositional sequences in Dorset [2, 4] and elsewhere implying a climatic control. Furthermore proven Milankovitch cycles in the Dorset [4] succession demonstrate that there is a strong climatic control at this time. A working hypothesis is that eustatic sea-level fall caused sediment instability resulting in higher energy and coarser-grained mass flow deposits, whereas eustatic sea-level rise resulted in lower energy mass flow deposits such as turbidites.
Upper image: Part of the spectacular mass flow deposits near Helmsdale that will be the focus of this study.
Lower image: Typical foreshore and cliff exposures in the study area.
The main objectives of this project are to:
1. Construct graphic logs and maps to record the nature of the deposits in time and space.
2. Complete palynological analysis of the mudrocks, integrate data with published ammonite biostratigraphy and develop biostratigraphic timescales for extra regional correlation.
3. Obtain a qualitative estimate of changes in weathering rate and transportation using palynomorph abundances and preservation respectively.
4. Construct a sequence stratigraphic interpretation of the deposits and use this to critically assess the relative role of tectonics and climate on the sediment packaging by comparison with sections elsewhere.
Studentship Projects
| Project Reference | Relationship | Related To | Start | End | Student Name |
|---|---|---|---|---|---|
| NE/S007350/1 | 01/10/2019 | 30/09/2027 | |||
| 1809490 | Studentship | NE/S007350/1 | 01/10/2016 | 28/02/2021 | Julie Harrald |
| Description | Annie Greenly Fund (research grant) |
| Amount | £1,323 (GBP) |
| Organisation | Geological Society of London |
| Sector | Learned Society |
| Country | United Kingdom |
| Start | 03/2018 |
| End | 12/2018 |
| Title | Characterising obscured sedimentary deposits from drone imagery on the foreshore |
| Description | Geological deposits exposed on the foreshore are often obscured by marine algae, sand or cobbles. Digital elevation models produced through photogrammetry from drone imagery have been used to characterise obscured sedimentary deposits and their lateral variation. |
| Type Of Material | Improvements to research infrastructure |
| Year Produced | 2019 |
| Provided To Others? | No |
| Impact | The method has been of considerable use in the research for this project. A short method paper has been drafted (not yet published) giving field examples of locations where the method has been of use. In addition, the paper addresses the practical considerations for gathering the drone imagery in a foreshore location. |
| Description | Drone survey with Birmingham University |
| Organisation | University of Birmingham |
| Country | United Kingdom |
| Sector | Academic/University |
| PI Contribution | First hand knowledge of the location, terrain and geological features of the area to be surveyed. Planning the daily field campaign in discussion with the drone operators, outlining the area to be covered, the resolution of images required, and the access and safety issues. Communication and collaboration with local land owners and residents. All logistical arrangements for the field campaign. |
| Collaborator Contribution | All drone operations - provision of equipment, operational expertise, detailed planning based on discussions with the geologist, insurance, method statements and flight permissions, carrying out all flights as required. |
| Impact | The project personnel and the collaborators from the University of Birmingham all work in Earth Sciences. Outputs to date include: Drone imagery (in several formats) which is being used to inform the project research analysis. Formal grant funding report related to the drone work (report sent to the Geological Society of London). Poster presentation and one minute introductory talk at the British Sedimentological Research Group conference (Dec 2018). We are in the process of writing a short paper on the work. |
| Start Year | 2018 |
| Description | Internship - natural capital |
| Organisation | Hereford and Worcester Earth Heritage Trust |
| Country | United Kingdom |
| Sector | Charity/Non Profit |
| PI Contribution | Understanding of the policy background to the project and establishing new links with relevant parties. |
| Collaborator Contribution | HW Earth Heritage Trust made a financial contribution to cover a three month internship allowing a short project on the role of geology in ecosystem services and natural capital assessments to be carried out. Their trustees also gave assistance with data gathering and presentation. |
| Impact | A final report of the exercise is being written and when complete, will be given to relevant policy makers. It should also be of use to practitioners in natural capital and ecosystem services work, geologists and land managers. |
| Start Year | 2019 |
| Description | BSRG poster 2017 |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | National |
| Primary Audience | Postgraduate students |
| Results and Impact | I presented a poster on the aims of my research and preliminary field data. I had one-to-one conversations with about 10 people. |
| Year(s) Of Engagement Activity | 2017 |
| Description | BSRG poster 2018 |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | National |
| Primary Audience | Postgraduate students |
| Results and Impact | I produced an academic poster on my research, the use of drone imagery to supplement my data and the methodology needed to capture such images in the geographical and geological setting of my field study area. I gave a one minute talk to the conference audience introducing the poster (about 100 people). It was on display for two days (to about 200 people) and I had one-to-one discussions with about 12 people during that time. |
| Year(s) Of Engagement Activity | 2018 |
| Description | Communication with local residents and landowners |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | Local |
| Primary Audience | Public/other audiences |
| Results and Impact | As part of my research I wanted to use a drone to obtain aerial images of shoreline where my research data is gathered. This required the consent of landowners and support of local residents. I had several meetings and telephone calls with landowners and residents, which involved explaining my main project, its purpose and likely outcomes, and led to further questions about the geology that I am studying. All were interested and supportive. This involved about 20 people, including representatives of a community land-owning / management group, a large landowning estate, two heritage centres and several individual residents. |
| Year(s) Of Engagement Activity | 2017,2018 |
| Description | poster presentation (VNN conference) |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | National |
| Primary Audience | Professional Practitioners |
| Results and Impact | A poster was presented at a conference held by the Valuing Nature Network. The aim was to draw attention to geology as a fundamental component of the natural environment and to open discussion about this so that contacts were made for future research. This outcome was achieved as around 30 new contacts were made at the event. Many of these people have participated in subsequent discussion, which will inform recommendations for policy. |
| Year(s) Of Engagement Activity | 2019 |