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This publication has emanated from research supported in part by a research grant from Science Foundation Ireland (SFI) under Grant Number 13/RC/2092 and co-funded under the European Regional Development Fund and by PIPCO RSG and its member companies.
1 iCRAG - Irish Centre for Research in Applied Geosciences, Ireland; 2 University College Cork, School of Biologial, Earth and Environmental Sciences, Cork, Ireland; 3 University of Bremen, Faculty of Geosciences, Bremen, Germany;4 Maynooth University, Department of Geography, Maynooth, Ireland; 5 Gaelectric Developments, Dublin, Ireland* [email protected]
1,2*Zsuzsanna Tóth
1,2Andrew J. Wheeler
3Volkhard Spiess
Morphology and development of the deeps and tunnel valleys in the western Irish Sea
3Stefan Wenau 4Stephen G. McCarron 5Mark Coughlan
Whittington, R.J., 1977: A late-glacial pattern in the Kish Bank area and post-glacial sediments in the Central Irish Sea. In: Kidson, C., Toolet, M.J. (Eds.), The Quaternary History of the Irish Sea. Seel House, Liverpool, pp. 55–68.
The Pinger and bathymetry data were collected in the framework of the INFOMAR programme of the Geological Survey Ireland. We thank Aodhan Fitzgerald and Rosemarie Butler (Marine Institute) for their work in organizing the cruise CV17013 (twice!). We are grateful to the captain and the crew of R/V Celtic Voyager for their work, support, cooperation and patience during the surveys and sampling. We were using the VISTA Desktop Seismic Data Processing and the KINGDOM softwares for seismic data processing and interpretation. We are grateful to Schlumberger and IHS Markit for providing the academic licences for these software packages.
ACKNOWLEDGEMENTS
REFERENCES
SEISMOACOUSTIC DATA IN THE IRISH SEA
278800 298800 318800 338800
5849800
5869800
5889800
5909800
5929800
N
Dublin
Wicklow Head
278800 298800 318800 338800
5849800
5869800
5889800
5909800
5929800
N
Bathymetry
Dublin
Wicklow Head
Seismic dataSparker data (2009, 2012)
Multichannel seismic data (2017, CV17013)
Sparker data (2017, CV17013)
EMODNet bathymetry
[TUNNEL VALLEY] SYSTEM?
Base of Unit III in Whittington (1977)
Codling Deep
Wicklow Trough
Lambay Deep
Deeps and valleys in the western Irish Sea such as the Lambay Deep, Codling Deep and Wicklow Trough, are believed to be part of a complex, linked valley system. During the last glaciation, the Irish Sea Basin was occupied by the Irish Sea Ice Stream that was fed by converging ice streams from British and Irish ice centres of the British-Irish Ice Sheet.
Interpretation of shallow seismic data by concluded that a till sheet blankets the pre-Pleistocene surface of the Irish Sea Basin and the valleys were cut into these subglacial sediments.The proposed formation of the channel system was (1) a sub-aerial fluviatile origin for the Codling Deep and Wicklow Trough during a period of low sea level based on morphology and minor tributaries from onshore rivers and (2) a subglacial stream erosion (tunnel valley) for the Lambay Deep. This late- to post-glacial, rectilinear drainage network is now partially infilled with Quaternary sediments and at present in parts it is undergoing active erosion.
The objective of our study is to reassess the morphology and formation theories of the deeps and valleys based on newly acquired seismo-acoustic data 40 years later and to define a Quaternary stratigraphic framework in the Irish sector of the Irish Sea. This poster displays the groundwork of our ongoing analysis.
Whittington (1977)
CV17013
Ÿ micro GI gun (central f=200 Hz)Ÿ Teledyne 96-channel streamer (220 m
max offset)Ÿ Sparker system (central f=600 kHz)
Seismic Survey
PRESENT MORPHOLOGY
20
60
80
100
0 10000 20000 30000
Depth
[m
]
Distance along profile [m]
V V‘B
40
120
Codling Deep
SouthRidge
50
20
30
40
0 2000 6000Distance along profile [m]
Depth
[m
]
W W‘C
4000 8000
Bray Bank
0.7°
1.4° 1.5°
0.7°
20
30
40
0 2000 6000
Distance along profile [m]
Depth
[m
]
X X‘D
4000
SouthRidge
Wicklow Trough
1°
80
20
40
60
0 2000
Distance along profile [m]
Depth
[m
]
Y Y‘
E
1000 3000
70
50
30
Wicklow Trough4.3° 2.7°
40
20
30
0 2000
Distance along profile [m]
Depth
[m
]
Z Z‘F
40001000 3000
Wicklow Trough4.4°
3°
−6˚10' −6˚00' −5˚50'
52˚50'
53˚00'
53˚10'
0 10
km
0
30
60
120
m
Wa
ter
de
pth
90
V‘
V
W
W‘
X
X‘
Y Y‘
Z
Z‘
Frazer Bank
Bray Bank
Codling Bank
Codling Deep
South Ridge
Wicklow Trough
Arklow Bank
IndiaBank
A
Dunes
Wicklow
Bray
−6˚00' −5˚50' −5˚40'
53˚20'
53˚30'
0 10
km
53˚40'
0
30
60
120
m
Wate
r depth
90
V
V‘
W
X
Y
Z
Z‘
Y‘
X‘
W‘
Dunefields
Bedrockoutcrops
Bedrockoutcrops
Lambay Island
A
60
80
100
120
0 10000 20000 30000
Depth
[m
]
Distance along profile [m]
V V‘B
65
70
75
0 1000 2000 3000
Depth
[m
]
Distance along profile [m]4000
80
W W‘
0.5° 0.4°
C
120
60
80
100
0 1000 2000 3000 4000Distance along profile [m]
Depth
[m
]
X X‘
5.5°
8.4°
3.1°
D
60
80
0 1000 2000 3000 4000Distance along profile [m]
100
Depth
[m
]
Y Y‘
2.5° 1.6°
E
75
60
65
70
0 1000 2000 3000Distance along profile [m]
Depth
[m
]
Z Z‘
1°0.7°
F
Lambay Deep
Codling Deep Wicklow Trough
INFOMARBathymetry
INFOMARBathymetry
deepest point: -134 m
deepest point: -119 m deepest point: -81 m
40
60
80
100
120
140
160
180
200
220
0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 11000 12000 13000 14000 15000 16000
40
60
80
100
120
140
160
180
200
220
- CV17013 090417.222217-3 -
20 20
40
60
80
100
120
140
160
180
200
220
0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 11000 12000
40
60
80
100
120
140
160
180
200
220
- CV17013 090417.171138-3 -
20 20
40
60
80
100
120
140
160
180
200
220
0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 11000 12000 13000 14000
40
60
80
100
120
140
160
180
200
220
- CV17013 090417.150057-2 -
2020
Wicklow Trough
SEISMOSTRATIGRAPHY Whittington’s seismostratigraphyUnit I = Pre-PleistoceneUnit II = TillUnit III = Horizontally-bedded sedimentary depositsUnit IV = Sand banks, sand waves or recent muds and siltsLambay Deep
Lambay Deep
Lambay Deep
Lambay Deep
TW
T (
ms)
Distance (m)
TW
T (
ms)
Distance (m)
TW
T (
ms)
Distance (m)
Seismostratigraphic units
[top of] Recent sediments
Shallow gas front
[top of] Sedimentary unit 2[top of] Sedimentary unit 1[top of] Till[top of] Bedrock
1st multiple of the seafloor
- Lambay Deep -
Codling Deep
20
40
60
80
100
120
140
160
180
- GeoB17-079 -
0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000
20
40
60
80
100
120
140
160
180
20
40
60
80
100
120
140
160
180
200
- GeoB17-071 -
1000 2000 3000 4000 5000 6000 7000
20
40
60
80
100
120
140
160
180
200
20
40
60
80
100
120
140
160
180
200
220
- GeoB17-064 -
3000 4000 5000 6000 7000
20
40
60
80
100
120
140
160
180
200
220
TW
T (
ms)
Distance (m)
TW
T (
ms)
Distance (m)
TW
T (
ms)
Distance (m)
Seismostratigraphic units
[top of] Recent sediments[top of] Sedimentary unit 2[top of] Sedimentary unit 1[top of] Till[top of] Bedrock
1st multiple of the seafloor
- Codling Deep,Wicklow Trough -
2nd multiple of the seafloor
Codling Deep
WicklowTrough
WicklowTrough