Clastic Dikes as a Possible Paleo-Earthquake Indicator in the Bengal Basin

Elizabeth Chamberlain, Steven L. Goodbred, R.L. Bain, T. Reimann, J. Wallinga, Michael S. Steckler, C. Von Hagke

Research output: Contribution to conferenceAbstractAcademic

Abstract

Historical earthquakes around the northeast Indian subcontinent have induced significant and widespread damage across the Bengal Basin. Recent work has also shown that the Indian-Burman plate boundary along the basin's eastern margin has built sufficient strain to cause a large magnitude earthquake, but little is known about the style and frequency of rupture. In all, the potential impact of large earthquakes within the region is well recognized, but neither well constrained nor well understood. Here, we report the discovery of large clastic dikes in the central Bengal Basin that appear to record a major paleo-seismic event. The site contains numerous laterally extensive sand dikes that intrude overbank river mud deposits, often reaching the ground surface. The dikes vary in width and comprise a set of at least two main intrusions, ˜10 m apart, largely parallel, and oriented east-west. The surface features have been reworked and are not well preserved. The age of the dikes is not yet known, but the breach appears to have occurred relatively contemporaneously with deposition of the intruded muds. In this case, the muds do not show signs of brittle fracture suggest that they were not yet well consolidated. Furthermore, the complete distortion of laminated bedding in a 30-cm thick layer of very fine sand within the mud section also indicates that the mud unit was relatively young and unconsolidated at the time of sand-dike emplacement. The location of the clastic dikes lies adjacent to a section of large, abandoned river channel that is ˜1.5 km wide and only partially filled with fine-grained muds. The size of the channel suggests that it may be a paleo-Ganges course, and the lack of sandy infill typical of this braided river suggest that it may have been abruptly abandoned. It is not yet known whether there is any correlation between the sand dikes and the channel abandonment. Our team is actively exploring this possibility.
Original languageEnglish
Publication statusPublished - 2018
EventAGU Fall Meeting - Washington, United States
Duration: 10 Dec 201814 Dec 2018
https://fallmeeting.agu.org/2018/welcome/

Conference

ConferenceAGU Fall Meeting
CountryUnited States
CityWashington
Period10/12/1814/12/18
Internet address

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clastic dike
mud
dike
earthquake
basin
sand
brittle fracture
braided river
Indian plate
earthquake magnitude
infill
river channel
plate boundary
indicator
rupture
emplacement
damage
river

Cite this

Chamberlain, E., Goodbred, S. L., Bain, R. L., Reimann, T., Wallinga, J., Steckler, M. S., & Von Hagke, C. (2018). Clastic Dikes as a Possible Paleo-Earthquake Indicator in the Bengal Basin. Abstract from AGU Fall Meeting, Washington, United States.
Chamberlain, Elizabeth ; Goodbred, Steven L. ; Bain, R.L. ; Reimann, T. ; Wallinga, J. ; Steckler, Michael S. ; Von Hagke, C. / Clastic Dikes as a Possible Paleo-Earthquake Indicator in the Bengal Basin. Abstract from AGU Fall Meeting, Washington, United States.
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abstract = "Historical earthquakes around the northeast Indian subcontinent have induced significant and widespread damage across the Bengal Basin. Recent work has also shown that the Indian-Burman plate boundary along the basin's eastern margin has built sufficient strain to cause a large magnitude earthquake, but little is known about the style and frequency of rupture. In all, the potential impact of large earthquakes within the region is well recognized, but neither well constrained nor well understood. Here, we report the discovery of large clastic dikes in the central Bengal Basin that appear to record a major paleo-seismic event. The site contains numerous laterally extensive sand dikes that intrude overbank river mud deposits, often reaching the ground surface. The dikes vary in width and comprise a set of at least two main intrusions, ˜10 m apart, largely parallel, and oriented east-west. The surface features have been reworked and are not well preserved. The age of the dikes is not yet known, but the breach appears to have occurred relatively contemporaneously with deposition of the intruded muds. In this case, the muds do not show signs of brittle fracture suggest that they were not yet well consolidated. Furthermore, the complete distortion of laminated bedding in a 30-cm thick layer of very fine sand within the mud section also indicates that the mud unit was relatively young and unconsolidated at the time of sand-dike emplacement. The location of the clastic dikes lies adjacent to a section of large, abandoned river channel that is ˜1.5 km wide and only partially filled with fine-grained muds. The size of the channel suggests that it may be a paleo-Ganges course, and the lack of sandy infill typical of this braided river suggest that it may have been abruptly abandoned. It is not yet known whether there is any correlation between the sand dikes and the channel abandonment. Our team is actively exploring this possibility.",
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year = "2018",
language = "English",
note = "AGU Fall Meeting ; Conference date: 10-12-2018 Through 14-12-2018",
url = "https://fallmeeting.agu.org/2018/welcome/",

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Chamberlain, E, Goodbred, SL, Bain, RL, Reimann, T, Wallinga, J, Steckler, MS & Von Hagke, C 2018, 'Clastic Dikes as a Possible Paleo-Earthquake Indicator in the Bengal Basin' AGU Fall Meeting, Washington, United States, 10/12/18 - 14/12/18, .

Clastic Dikes as a Possible Paleo-Earthquake Indicator in the Bengal Basin. / Chamberlain, Elizabeth; Goodbred, Steven L.; Bain, R.L. ; Reimann, T.; Wallinga, J.; Steckler, Michael S.; Von Hagke, C.

2018. Abstract from AGU Fall Meeting, Washington, United States.

Research output: Contribution to conferenceAbstractAcademic

TY - CONF

T1 - Clastic Dikes as a Possible Paleo-Earthquake Indicator in the Bengal Basin

AU - Chamberlain, Elizabeth

AU - Goodbred, Steven L.

AU - Bain, R.L.

AU - Reimann, T.

AU - Wallinga, J.

AU - Steckler, Michael S.

AU - Von Hagke, C.

PY - 2018

Y1 - 2018

N2 - Historical earthquakes around the northeast Indian subcontinent have induced significant and widespread damage across the Bengal Basin. Recent work has also shown that the Indian-Burman plate boundary along the basin's eastern margin has built sufficient strain to cause a large magnitude earthquake, but little is known about the style and frequency of rupture. In all, the potential impact of large earthquakes within the region is well recognized, but neither well constrained nor well understood. Here, we report the discovery of large clastic dikes in the central Bengal Basin that appear to record a major paleo-seismic event. The site contains numerous laterally extensive sand dikes that intrude overbank river mud deposits, often reaching the ground surface. The dikes vary in width and comprise a set of at least two main intrusions, ˜10 m apart, largely parallel, and oriented east-west. The surface features have been reworked and are not well preserved. The age of the dikes is not yet known, but the breach appears to have occurred relatively contemporaneously with deposition of the intruded muds. In this case, the muds do not show signs of brittle fracture suggest that they were not yet well consolidated. Furthermore, the complete distortion of laminated bedding in a 30-cm thick layer of very fine sand within the mud section also indicates that the mud unit was relatively young and unconsolidated at the time of sand-dike emplacement. The location of the clastic dikes lies adjacent to a section of large, abandoned river channel that is ˜1.5 km wide and only partially filled with fine-grained muds. The size of the channel suggests that it may be a paleo-Ganges course, and the lack of sandy infill typical of this braided river suggest that it may have been abruptly abandoned. It is not yet known whether there is any correlation between the sand dikes and the channel abandonment. Our team is actively exploring this possibility.

AB - Historical earthquakes around the northeast Indian subcontinent have induced significant and widespread damage across the Bengal Basin. Recent work has also shown that the Indian-Burman plate boundary along the basin's eastern margin has built sufficient strain to cause a large magnitude earthquake, but little is known about the style and frequency of rupture. In all, the potential impact of large earthquakes within the region is well recognized, but neither well constrained nor well understood. Here, we report the discovery of large clastic dikes in the central Bengal Basin that appear to record a major paleo-seismic event. The site contains numerous laterally extensive sand dikes that intrude overbank river mud deposits, often reaching the ground surface. The dikes vary in width and comprise a set of at least two main intrusions, ˜10 m apart, largely parallel, and oriented east-west. The surface features have been reworked and are not well preserved. The age of the dikes is not yet known, but the breach appears to have occurred relatively contemporaneously with deposition of the intruded muds. In this case, the muds do not show signs of brittle fracture suggest that they were not yet well consolidated. Furthermore, the complete distortion of laminated bedding in a 30-cm thick layer of very fine sand within the mud section also indicates that the mud unit was relatively young and unconsolidated at the time of sand-dike emplacement. The location of the clastic dikes lies adjacent to a section of large, abandoned river channel that is ˜1.5 km wide and only partially filled with fine-grained muds. The size of the channel suggests that it may be a paleo-Ganges course, and the lack of sandy infill typical of this braided river suggest that it may have been abruptly abandoned. It is not yet known whether there is any correlation between the sand dikes and the channel abandonment. Our team is actively exploring this possibility.

M3 - Abstract

ER -

Chamberlain E, Goodbred SL, Bain RL, Reimann T, Wallinga J, Steckler MS et al. Clastic Dikes as a Possible Paleo-Earthquake Indicator in the Bengal Basin. 2018. Abstract from AGU Fall Meeting, Washington, United States.