Imperial College London
Portrait Picture

Emeritus ProfessorLidiaLonergan

Faculty of Engineering, Department of Earth Science & Engineering

Emeritus Reader of Geotectonics
 
 
 
//

Contact

 

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

 
 
//

Location

 

3.48Royal School of MinesSouth Kensington Campus

//

Summary

 

Publications

Citation

BibTex format

@article{McDermott:2019:10.1016/j.epsl.2019.05.049,
author = {McDermott, C and Collier, JS and Lonergan, L and Fruehn, J and Bellingham, P},
doi = {10.1016/j.epsl.2019.05.049},
journal = {Earth and Planetary Science Letters},
pages = {14--24},
title = {Seismic velocity structure of seaward-dipping reflectors on the South American continental margin},
url = {http://dx.doi.org/10.1016/j.epsl.2019.05.049},
volume = {521},
year = {2019}
}
Download

RIS format (EndNote, RefMan)

TY  - JOUR
AB  - Seaward dipping reflectors (SDRs) are a key feature within the continent to ocean transition zone of volcanic passive margins. Here we conduct an automated pre-stack depth-migration imaging analysis of commercial seismic data from the volcanic margins of South America. The method used an isotropic, ray-based approach of iterative velocity model building based on the travel time inversion of residual pre-stack depth migration move-out. We find two distinct seismic velocity patterns within the SDRs. While both types show a general increase in velocity with depth consistent with expected compaction and alteration/metamorphic trends, those SDRs that lie within faulted half grabens also have high velocity zones at their down-dip ends. The velocity anomalies are generally concordant with the reflectivity and so we attribute them to the presence of dolerite sills that were injected into the lava pile. The sills therefore result from late-stage melt delivery along the large landward-dipping faults that bound them. In contrast the more outboard SDRs show no velocity anomalies, are more uniform spatially and have unfaulted basal contacts. Our observations imply that the SDRs document a major change in rift architecture, with magmatism linked with early extension and faulting of the upper brittle crust transitioning into more organised, dike-fed eruptions similar to seafloor spreading.
AU  - McDermott,C
AU  - Collier,JS
AU  - Lonergan,L
AU  - Fruehn,J
AU  - Bellingham,P
DO  - 10.1016/j.epsl.2019.05.049
EP  - 24
PY  - 2019///
SN  - 0012-821X
SP  - 14
TI  - Seismic velocity structure of seaward-dipping reflectors on the South American continental margin
T2  - Earth and Planetary Science Letters
UR  - http://dx.doi.org/10.1016/j.epsl.2019.05.049
UR  - http://hdl.handle.net/10044/1/71011
VL  - 521
ER  -
Download