Imperial College London
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Emeritus ProfessorLidiaLonergan

Faculty of Engineering, Department of Earth Science & Engineering

Emeritus Reader of Geotectonics
 
 
 
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Contact

 

+44 (0)20 7594 6465l.lonergan Website

 
 
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Location

 

3.48Royal School of MinesSouth Kensington Campus

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Summary

 

Publications

Citation

BibTex format

@article{McDermott:2018:10.1029/2017TC004923,
author = {McDermott, C and Lonergan, L and Collier, JS and McDermott, KG and Bellingham, P},
doi = {10.1029/2017TC004923},
journal = {Tectonics},
pages = {3303--3327},
title = {Characterization of seaward-dipping reflectors along the South American Atlantic Margin and implications for continental breakup},
url = {http://dx.doi.org/10.1029/2017TC004923},
volume = {37},
year = {2018}
}
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RIS format (EndNote, RefMan)

TY  - JOUR
AB  - Thick packages of lavas forming seawarddipping reflectors (SDRs) are diagnostic features of volcanic passive margins. Despite their significance to continental breakup studies, their formation mechanism is still debated. We use ~22,000 km of highquality, depthmigrated, seismic data to document the threedimensional geometry of SDRs offshore South America. We find two types: Type I are planar and occur as faultbounded wedges. Type II are characterized by reflections that become more convexupward in the downdip direction and terminate against a subhorizontal base. We interpret the transition from Type I to Type II SDRs to represent a continuum from continental rifting to full plate separation with formation of new, subaerially generated, magmatic crust. Type I SDRs formed in half grabens during the stretching of continental crust, while Type II lavas infill the space produced by flexing of the crust due to the solidification of the underlying feeder dikes as the magmatic crust moved away from the spreading center. Type II SDRs vary in length and thickness along the margin. In the north, close to the Paraná flood basalts, they are long (tens of kilometers), reach thicknesses of up to 15 km, and have an across margin width of up to 600 km. To the south the Type II SDRs are thinner with lava lengths of <10 km. We propose that Type II lavas in the north erupted from a subaerial, plate spreading center above the Tristan mantle plume and that the shorter lava flows to the south indicates eruption into water, consistent with a cooler, offplume mantle.
AU  - McDermott,C
AU  - Lonergan,L
AU  - Collier,JS
AU  - McDermott,KG
AU  - Bellingham,P
DO  - 10.1029/2017TC004923
EP  - 3327
PY  - 2018///
SN  - 0278-7407
SP  - 3303
TI  - Characterization of seaward-dipping reflectors along the South American Atlantic Margin and implications for continental breakup
T2  - Tectonics
UR  - http://dx.doi.org/10.1029/2017TC004923
UR  - https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2017TC004923
UR  - http://hdl.handle.net/10044/1/64298
VL  - 37
ER  -
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