The Northern Andes: A Review of the Ecuadorian Pacific Margin

Baldock, J. W.

doi:10.1007/978-1-4613-2351-8_5

Cited by 18 publications

(16 citation statements)

References 34 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Such basement thinning accompanied by a 1‐ to 3‐km thickening of overlying low‐velocity sediment may contribute to variable interplate lithostatic pressure across the Manglares fault. Because the margin basement is a mosaic of heterogeneous, tectonically accreted oceanic blocks [ Baldock , 1983; Reynaud et al , 1999], its physical properties are expected to vary across the oceanic terranes, and influence the margin strength and interplate friction as well.…”

Section: Discussionmentioning

confidence: 99%

Are rupture zone limits of great subduction earthquakes controlled by upper plate structures? Evidence from multichannel seismic reflection data acquired across the northern Ecuador–southwest Colombia margin

Collot

Marcaillou²,

Sage³

et al. 2004

J. Geophys. Res.

132

160

View full text Add to dashboard Cite

Subduction of the Nazca plate beneath the Ecuador‐Colombia margin has produced four megathrust earthquakes during the last century. The 500‐km‐long rupture zone of the 1906 (Mw = 8.8) event was partially reactivated by three thrust events, in 1942 (Mw = 7.8), 1958 (Mw = 7.7), and 1979 (Mw = 8.2), whose rupture zones abut one another. Multichannel seismic reflection and bathymetric data acquired during the SISTEUR cruise show evidence that the margin wedge is segmented by transverse crustal faults that potentially correlate with the limits of the earthquake coseismic slip zones. The Paleogene‐Neogene Jama Quininde and Esmeraldas crustal faults define a ∼200‐km‐long margin crustal block that coincides with the 1942 earthquake rupture zone. Subduction of the buoyant Carnegie Ridge is inferred to partially lock the plate interface along central Ecuador. However, coseismic slip during the 1942 and 1906 earthquakes may have terminated against the subducted northern flank of the ridge. We report on a newly identified Manglares crustal fault that cuts transversally through the margin wedge and correlates with the limit between the 1958 and 1979 rupture zones. During the earthquake cycle the fault is associated with high‐stress concentration on the plate interface. An outer basement high, which bounds the margin seaward of the 1958 rupture zone, may act as a deformable buttress to seaward propagation of coseismic slip along a megathrust splay fault. Coseismic uplift of the basement high is interpreted as the cause for the 1958 tsunami. We propose a model of weak transverse faults which reduce coupling between adjacent margin segments, together with a splay fault and an asperity along the plate interface as controlling the seismogenic rupture of the 1958 earthquake.

show abstract

Section: Discussionmentioning

confidence: 99%

Are rupture zone limits of great subduction earthquakes controlled by upper plate structures? Evidence from multichannel seismic reflection data acquired across the northern Ecuador–southwest Colombia margin

Collot

Marcaillou²,

Sage³

et al. 2004

J. Geophys. Res.

132

160

View full text Add to dashboard Cite

show abstract

“…The Napo phosphates were deposited at the transition from bioclastic limestone deposition to black shale deposition in a back-arc basin along the west coast South America, in an equatorial paleolatitude similar to today and conducive to upwelling currents (Veeh et al, 1973(Veeh et al, , 1974Manheim et al, 1975;Burnett, 1977;Baldock, 1985) (see Figs. 1 and 2).…”

Section: Depositional Environmentmentioning

confidence: 97%

“…In the lowermost Cretaceous, marine transgression inaugurated the deposition of Aptian to Coniacian mixed shelf, slope and basinal clastic-carbonate units in the retro-arc basin and on the continental shelf ( Fig. 2) (Baldock, 1985). Sedimentation was primarily controlled by marine transgressions and regressions on the shelf (Tschopp, 1956).…”

Section: Geological Backgroundmentioning

confidence: 99%

“…1A) (Dashwood and Abbots, 1990). It is underlain by thinned Precambrian rocks of the Guyana shield and presently has two distinct geological and geomorphological zones, a sub-Andean zone to the west adjacent to the Andes, and an Upper Amazon zone to the east, which were formed during Andean tectonic deformation during the late Cenozoic (Baldock, 1985). The Oriente Basin has the most important oil reservoir found in Ecuador, in the Cretaceous Napo Formation (Feininger, 1975), which also hosts the economic phosphate deposits studied in this paper.…”

Section: Geological Backgroundmentioning

confidence: 99%

See 1 more Smart Citation

Paleoenvironments and origin of the sedimentary phosphorites of the Napo Formation (Late Cretaceous, Oriente Basin, Ecuador)

Brookfield¹,

Hemmings²,

Straaten³

2009

Journal of South American Earth Sciences

View full text Add to dashboard Cite

“…The basement of the Ecuador margin consists of allochtonous Cretaceous oceanic terranes [Gansser, 1973;Gossens and Rose, 1973;Reynaud et al, 1999]. The terranes comprise the high-Vp velocity (3.5-6 km/s) basaltic complex of the Piñon Formation that crops out on La Plata Island [Baldock, 1983] and extend close to the trench [Graindorge et al, 2004], where the margin outer wedge is erosive [Sage et al, 2006].…”

Section: Geodynamic Context Seismicity and Interseismic Couplingmentioning

confidence: 99%

Subducted oceanic relief locks the shallow megathrust in central Ecuador

et al. 2017

View full text Add to dashboard Cite

Whether subducted oceanic reliefs such as seamounts promote seismic rupture or aseismic slip remains controversial. Here we use swath bathymetry, prestack depth‐migrated multichannel seismic reflection lines, and wide‐angle seismic data collected across the central Ecuador subduction segment to reveal a broad ~55 km × 50 km, ~1.5–2.0 km high, low height‐to‐width ratio, multipeaked, sediment‐bare, shallow subducted oceanic relief. Owing to La Plata Island and the coastline being located, respectively, ~35 km and ~50–60 km from the trench, GPS measurements allow us to demonstrate that the subducted oceanic relief spatially correlates to a shallow, ~80 km × 55 km locked interplate asperity within a dominantly creeping subduction segment. The oceanic relief geometrical anomaly together with its highly jagged topography, the absence of a subduction channel, and a stiff erosive oceanic margin are found to be long‐term geological characteristics associated with the shallow locking of the megathrust. Although the size and level of locking observed at the subducted relief scale could produce an Mw >7+ event, no large earthquakes are known to have happened for several centuries. On the contrary, frequent slow slip events have been recorded since 2010 within the locked patch, and regular seismic swarms have occurred in this area during the last 40 years. These transient processes, together with the rough subducted oceanic topography, suggest that interplate friction might actually be heterogeneous within the locked patch. Additionally, we find that the subducted relief undergoes internal shearing and produces a permanent flexural bulge of the margin, which uplifted La Plata Island.

show abstract

The Northern Andes: A Review of the Ecuadorian Pacific Margin

Cited by 18 publications

References 34 publications

Are rupture zone limits of great subduction earthquakes controlled by upper plate structures? Evidence from multichannel seismic reflection data acquired across the northern Ecuador–southwest Colombia margin

Are rupture zone limits of great subduction earthquakes controlled by upper plate structures? Evidence from multichannel seismic reflection data acquired across the northern Ecuador–southwest Colombia margin

Paleoenvironments and origin of the sedimentary phosphorites of the Napo Formation (Late Cretaceous, Oriente Basin, Ecuador)

Subducted oceanic relief locks the shallow megathrust in central Ecuador

Contact Info

Product

Resources

About