Continent-Ocean Transition or Boundary?: Crowd-sourced seismic interpretations of the East-India Passive Margin

Clare Bond; Juan Alcalde; Rob Butler; Ken McDermott; Ramon Carbonell

doi:10.1029/2022TC007624

Continent-Ocean Transition or Boundary? Crowd-sourced seismic interpretations of the East-India Passive Margin

Clare Bond, Juan Alcalde^* (Corresponding Author), Rob Butler, Ken McDermott, Ramon Carbonell

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

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Abstract

On the edge of our continents, oceanic crust meets continental crust. At passive margins, those where there is no active tectonics, subduction or transform faulting, these crustal types are connected as sharp continent-ocean boundaries (COB) or as diffuse continent-ocean transition (COT) zones. Passive margins are hard to explore and consequently relatively little is known about their morphology or the geological processes of their formation. Here we elicit and analyse seismic image interpretations of the passive margin offshore East India conducted by 17 groups of geoscientists to better understand the differences, or lack therein, of COB or COT interpretations of the margin. The group interpretations provide a wide range of margin models, five of which are abrupt COB based and 11 which are diffuse COT based. However, interpretations within the COB set vary in the placement of the boundary line between continental and oceanic crust, the boundary placement lying within the range of interpreted COT zones, with the average COB location falling in the centre of the interpreted COT zones. These crowd-sourced results are then compared with ten published interpretations across the margin, which show COB and COT zones falling in the same area. These findings raise questions as to the real differences in COB and COT models and the geological processes involved in their formation. Considering this, we discuss the implications for passive margin models and the use of Wisdom of Crowds-type approaches in reflecting on both the range of interpretation-based models and in the value of determining ‘average’ model approaches.

Original language	English
Article number	e2022TC007624
Number of pages	16
Journal	Tectonics
Volume	42
Issue number	8
Early online date	28 Jul 2023
DOIs	https://doi.org/10.1029/2022TC007624
Publication status	Published - 8 Aug 2023

Bibliographical note

AcknowledgmentsThe authors would like to thank the full SEISMIX 2016 organization team and participants for facilitating and taking part in the experiment in Aviemore (Scotland). ION is thanked for supplying the seismic profile used in the experiments. Dr. Eagles and Dr. Pérez-Díaz are thanked for kindly sharing the interpretations of the E-India margin. JA is funded by “Juan de la Cierva-Incorporación” fellow-ship IJC2018-036074-I and “Ramón y Cajal” fellowship RYC2021-033872-I, funded by MCIN/AEI/https://doi.org/10.13039/501100011033 and the European Union NextGenerationEU/PRTR. We thank the reviewers for their constructive comments, and Jonathan Aitchison for the editorial guidance.

Data Availability Statement

The ION's IndiaSPAN-1000 2D regional seismic line used in this experiment was lent to the authors by ION and it is not available for confidentiality reasons, but images of the line (with different display characteristics) have been published and are shown in Figure 2 of this article.

Keywords

passive margins
seismic interpretation
wisdom of crowds
continent-ocean boundary
continent-ocean transition
East India Margin

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Cite this

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title = "Continent-Ocean Transition or Boundary?: Crowd-sourced seismic interpretations of the East-India Passive Margin",

abstract = "On the edge of our continents, oceanic crust meets continental crust. At passive margins, those where there is no active tectonics, subduction or transform faulting, these crustal types are connected as sharp continent-ocean boundaries (COB) or as diffuse continent-ocean transition (COT) zones. Passive margins are hard to explore and consequently relatively little is known about their morphology or the geological processes of their formation. Here we elicit and analyse seismic image interpretations of the passive margin offshore East India conducted by 17 groups of geoscientists to better understand the differences, or lack therein, of COB or COT interpretations of the margin. The group interpretations provide a wide range of margin models, five of which are abrupt COB based and 11 which are diffuse COT based. However, interpretations within the COB set vary in the placement of the boundary line between continental and oceanic crust, the boundary placement lying within the range of interpreted COT zones, with the average COB location falling in the centre of the interpreted COT zones. These crowd-sourced results are then compared with ten published interpretations across the margin, which show COB and COT zones falling in the same area. These findings raise questions as to the real differences in COB and COT models and the geological processes involved in their formation. Considering this, we discuss the implications for passive margin models and the use of Wisdom of Crowds-type approaches in reflecting on both the range of interpretation-based models and in the value of determining {\textquoteleft}average{\textquoteright} model approaches. ",

keywords = "passive margins, seismic interpretation, wisdom of crowds, continent-ocean boundary, continent-ocean transition, East India Margin",

author = "Clare Bond and Juan Alcalde and Rob Butler and Ken McDermott and Ramon Carbonell",

note = "AcknowledgmentsThe authors would like to thank the full SEISMIX 2016 organization team and participants for facilitating and taking part in the experiment in Aviemore (Scotland). ION is thanked for supplying the seismic profile used in the experiments. Dr. Eagles and Dr. P{\'e}rez-D{\'i}az are thanked for kindly sharing the interpretations of the E-India margin. JA is funded by “Juan de la Cierva-Incorporaci{\'o}n” fellow-ship IJC2018-036074-I and “Ram{\'o}n y Cajal” fellowship RYC2021-033872-I, funded by MCIN/AEI/https://doi.org/10.13039/501100011033 and the European Union NextGenerationEU/PRTR. We thank the reviewers for their constructive comments, and Jonathan Aitchison for the editorial guidance.",

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TY - JOUR

T1 - Continent-Ocean Transition or Boundary?

T2 - Crowd-sourced seismic interpretations of the East-India Passive Margin

AU - Bond, Clare

AU - Alcalde, Juan

AU - Butler, Rob

AU - McDermott, Ken

AU - Carbonell, Ramon

N1 - AcknowledgmentsThe authors would like to thank the full SEISMIX 2016 organization team and participants for facilitating and taking part in the experiment in Aviemore (Scotland). ION is thanked for supplying the seismic profile used in the experiments. Dr. Eagles and Dr. Pérez-Díaz are thanked for kindly sharing the interpretations of the E-India margin. JA is funded by “Juan de la Cierva-Incorporación” fellow-ship IJC2018-036074-I and “Ramón y Cajal” fellowship RYC2021-033872-I, funded by MCIN/AEI/https://doi.org/10.13039/501100011033 and the European Union NextGenerationEU/PRTR. We thank the reviewers for their constructive comments, and Jonathan Aitchison for the editorial guidance.

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N2 - On the edge of our continents, oceanic crust meets continental crust. At passive margins, those where there is no active tectonics, subduction or transform faulting, these crustal types are connected as sharp continent-ocean boundaries (COB) or as diffuse continent-ocean transition (COT) zones. Passive margins are hard to explore and consequently relatively little is known about their morphology or the geological processes of their formation. Here we elicit and analyse seismic image interpretations of the passive margin offshore East India conducted by 17 groups of geoscientists to better understand the differences, or lack therein, of COB or COT interpretations of the margin. The group interpretations provide a wide range of margin models, five of which are abrupt COB based and 11 which are diffuse COT based. However, interpretations within the COB set vary in the placement of the boundary line between continental and oceanic crust, the boundary placement lying within the range of interpreted COT zones, with the average COB location falling in the centre of the interpreted COT zones. These crowd-sourced results are then compared with ten published interpretations across the margin, which show COB and COT zones falling in the same area. These findings raise questions as to the real differences in COB and COT models and the geological processes involved in their formation. Considering this, we discuss the implications for passive margin models and the use of Wisdom of Crowds-type approaches in reflecting on both the range of interpretation-based models and in the value of determining ‘average’ model approaches.

AB - On the edge of our continents, oceanic crust meets continental crust. At passive margins, those where there is no active tectonics, subduction or transform faulting, these crustal types are connected as sharp continent-ocean boundaries (COB) or as diffuse continent-ocean transition (COT) zones. Passive margins are hard to explore and consequently relatively little is known about their morphology or the geological processes of their formation. Here we elicit and analyse seismic image interpretations of the passive margin offshore East India conducted by 17 groups of geoscientists to better understand the differences, or lack therein, of COB or COT interpretations of the margin. The group interpretations provide a wide range of margin models, five of which are abrupt COB based and 11 which are diffuse COT based. However, interpretations within the COB set vary in the placement of the boundary line between continental and oceanic crust, the boundary placement lying within the range of interpreted COT zones, with the average COB location falling in the centre of the interpreted COT zones. These crowd-sourced results are then compared with ten published interpretations across the margin, which show COB and COT zones falling in the same area. These findings raise questions as to the real differences in COB and COT models and the geological processes involved in their formation. Considering this, we discuss the implications for passive margin models and the use of Wisdom of Crowds-type approaches in reflecting on both the range of interpretation-based models and in the value of determining ‘average’ model approaches.

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KW - East India Margin

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DO - 10.1029/2022TC007624

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SN - 0278-7407

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JO - Tectonics

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