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Article: The recent history of the Galapagos triple junction preserved on the Pacific plate

Smith, Deborah K / Schouten, Hans / Montési, Laurent / Zhu, Wenlu

Earth and planetary science letters. 2013 June, v. 371-372

2013

Abstract: At the Galapagos triple junction, the Cocos and Nazca plates are broken by a succession of transient rifts north and south of the Cocos–Nazca (C–N) Rift. Modeling has suggested that each rift initiated at the East Pacific Rise (EPR), its location ... ...

Abstract	At the Galapagos triple junction, the Cocos and Nazca plates are broken by a succession of transient rifts north and south of the Cocos–Nazca (C–N) Rift. Modeling has suggested that each rift initiated at the East Pacific Rise (EPR), its location controlled by the distance of the C–N Rift tip from the EPR. Evidence on the Pacific plate confirms that each transient rift formed a true RRR triple junction with the EPR and clarifies the history of the region. At ∼1.5Ma the triple junctions began jumping rapidly toward the C–N Rift suggesting that the C–N Rift tip moved closer to the EPR. Pacific abyssal hills became broad and shallow indicating enhanced magma supply to the region. At ∼1.4Ma, the Galapagos microplate developed when extension became fixed on the southern transient rift to form the South scarp of the future Dietz rift basin. Lavas flooded the area and a Galapagos–Nazca magmatic spreading center initiated at the EPR. We suggest that a hotspot was approaching the southern triple junction from the west. The hotspot crossed to the Nazca plate ∼1.25Ma. Dietz seamount formed within the young spreading center, dikes intruded Dietz rift basin, and eruptions built volcanic ridges. Since ∼0.8Ma magmatic spreading has jumped northward twice, most recently to Dietz volcanic ridge. Amagmatic extension to the east has formed the large North scarp of Dietz rift basin. Northward jumping of the southern triple junction has maintained the microplate boundary close to the proposed hotspot.
Keywords	basins ; hills ; lava ; models
Language	English
Dates of publication	2013-06
Size	p. 6-15.
Publishing place	Elsevier B.V.
Document type	Article
ZDB-ID	1466659-5
ISSN	1385-013X ; 0012-821X
ISSN (online)	1385-013X
ISSN	0012-821X
DOI	10.1016/j.epsl.2013.04.018
Database	NAL-Catalogue (AGRICOLA)

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Article: Transient rifting north of the Galápagos Triple Junction

Mitchell, Garrett A / Montési, Laurent G.J / Zhu, Wenlu / Smith, Deborah K / Schouten, Hans

Earth and planetary science letters. 2011 July 15, v. 307, no. 3-4

2011

Abstract: Seafloor bathymetry north of the Galápagos microplate in the Eastern Pacific Ocean contains evidence for a sequence of short-lived rifts cross-cutting abyssal hills adjacent to the East Pacific Rise. These secondary rifts are sub-parallel to the ... ...

Abstract	Seafloor bathymetry north of the Galápagos microplate in the Eastern Pacific Ocean contains evidence for a sequence of short-lived rifts cross-cutting abyssal hills adjacent to the East Pacific Rise. These secondary rifts are sub-parallel to the Incipient Rift that marks the current triple junction at 2°40′N and are nearly perpendicular to the direction of opening between the Cocos and Nazca plates. Secondary rifts likely initiated from the EPR by lithospheric cracking. Eventually, their activity stopped and they were carried away from the triple junction as part of the Cocos plate. We developed and analyzed numerical models of rift interaction to understand the evolution of rift configuration in this area. By varying the geometry and locations of rifts, we constrain the factors that have led to the location and orientation of secondary rifts at the northern Galápagos Triple Junction. Interaction between secondary rifts and the Cocos-Nazca Rift results in ~10° clockwise rotation of the secondary rift propagation direction, as observed. Furthermore, if a rift has become detached from the East Pacific Rise, a zone of reduced tension is present ahead of the rift tip, prohibiting its connection to the East Pacific Rise. Two zones of tensile stress enhancement develop along the East Pacific Rise next to the detached rift and control where new cracks are likely to form. Although the magnitude of tensile stress enhancement is controlled by the gap between the detached rift and the East Pacific Rise, whether the new rift forms north or south of the detached rift is controlled by position of the Cocos-Nazca Rift. Therefore, the sequence of ancient rifts found northeast of the current triple junction at 2°40′N represents the natural consequence of rift disconnection events and their position records the kinematic history of the gap between the East Pacific Rise and the Cocos-Nazca Rift.
Keywords	cracking ; hills ; mathematical models ; Pacific Ocean
Language	English
Dates of publication	2011-0715
Size	p. 461-469.
Publishing place	Elsevier B.V.
Document type	Article
ZDB-ID	1466659-5
ISSN	1385-013X ; 0012-821X
ISSN (online)	1385-013X
ISSN	0012-821X
DOI	10.1016/j.epsl.2011.05.027
Database	NAL-Catalogue (AGRICOLA)

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Article ; Online: An ultraslow-spreading class of ocean ridge.

Dick, Henry J B / Lin, Jian / Schouten, Hans

Nature

2003 Volume 426, Issue 6965, Page(s) 405–412

Abstract: New investigations of the Southwest Indian and Arctic ridges reveal an ultraslow-spreading class of ocean ridge that is characterized by intermittent volcanism and a lack of transform faults. We find that the mantle beneath such ridges is emplaced ... ...

Abstract	New investigations of the Southwest Indian and Arctic ridges reveal an ultraslow-spreading class of ocean ridge that is characterized by intermittent volcanism and a lack of transform faults. We find that the mantle beneath such ridges is emplaced continuously to the seafloor over large regions. The differences between ultraslow- and slow-spreading ridges are as great as those between slow- and fast-spreading ridges. The ultraslow-spreading ridges usually form at full spreading rates less than about 12 mm yr(-1), though their characteristics are commonly found at rates up to approximately 20 mm yr(-1). The ultraslow-spreading ridges consist of linked magmatic and amagmatic accretionary ridge segments. The amagmatic segments are a previously unrecognized class of accretionary plate boundary structure and can assume any orientation, with angles relative to the spreading direction ranging from orthogonal to acute. These amagmatic segments sometimes coexist with magmatic ridge segments for millions of years to form stable plate boundaries, or may displace or be displaced by transforms and magmatic ridge segments as spreading rate, mantle thermal structure and ridge geometry change.
Language	English
Publishing date	2003-11-27
Publishing country	England
Document type	Journal Article
ZDB-ID	120714-3
ISSN	1476-4687 ; 0028-0836
ISSN (online)	1476-4687
ISSN	0028-0836
DOI	10.1038/nature02128
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Article ; Online: Counter-rotating microplates at the Galapagos triple junction.

Klein, Emily M / Smith, Deborah K / Williams, Clare M / Schouten, Hans

Nature

2005 Volume 433, Issue 7028, Page(s) 855–858

Abstract: An 'incipient' spreading centre east of (and orthogonal to) the East Pacific Rise at 2 degrees 40' N has been identified as forming a portion of the northern boundary of the Galapagos microplate. This spreading centre was described as a slowly diverging, ...

Abstract	An 'incipient' spreading centre east of (and orthogonal to) the East Pacific Rise at 2 degrees 40' N has been identified as forming a portion of the northern boundary of the Galapagos microplate. This spreading centre was described as a slowly diverging, westward propagating rift, tapering towards the East Pacific Rise. Here we present evidence that the 'incipient rift' has also rifted towards the east and opens anticlockwise about a pivot at its eastern end. The 'incipient rift' then bounds a second microplate, north of the clockwise-rotating Galapagos microplate. The Galapagos triple junction region, in the eastern equatorial Pacific Ocean, thus consists of two counter-rotating microplates partly separated by the Hess Deep rift. Our kinematic solution for microplate motion relative to the major plates indicates that the two counter-rotating microplates may be treated as rigid blocks driven by drag on the microplates' edges3.
Language	English
Publishing date	2005-02-24
Publishing country	England
Document type	Journal Article
ZDB-ID	120714-3
ISSN	1476-4687 ; 0028-0836
ISSN (online)	1476-4687
ISSN	0028-0836
DOI	10.1038/nature03262
Database	MEDical Literature Analysis and Retrieval System OnLINE

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Book ; Conference proceedings ; Online: Petrography and geochemical composition of the Atlantis II Fracture Zone, supplementary data to: Dick, Henry JB; Schouten, Hans; Meyer, Peter S; Gallo, David G; Bergh, Hugh; Tyce, Robert; Patriat, Phillipe; Johnson, Kevin TM; Snow, Jon; Fisher, Andrew T (1991): Tectonic evolution of the Atlantis II fracture zone. In: Von Herzen, RP; Robinson, PT; et al. (eds.), Proceedings of the Ocean Drilling Program, Scientific Results, College Station, TX (Ocean Drilling Program), 118, 359-398

Dick, Henry JB / Bergh, Hugh / Fisher, Andrew T / Gallo, David G / Johnson, Kevin TM / Meyer, Peter S / Patriat, Phillipe / Schouten, Hans / Snow, Jon / Tyce, Robert

1991

Abstract: SeaBeam echo sounding, seismic reflection, magnetics, and gravity profiles were run along closely spaced tracks (5 km) parallel to the Atlantis II Fracture Zone on the Southwest Indian Ridge, giving 80% bathymetric coverage of a 30- * 170-nmi strip ... ...

Abstract	SeaBeam echo sounding, seismic reflection, magnetics, and gravity profiles were run along closely spaced tracks (5 km) parallel to the Atlantis II Fracture Zone on the Southwest Indian Ridge, giving 80% bathymetric coverage of a 30- * 170-nmi strip centered over the fracture zone. The southern and northern rift valleys of the ridge were clearly defined and offset north-south by 199 km. The rift valleys are typical of those found elsewhere on the Southwest Indian Ridge, with relief of more than 2200 m and widths from 22 to 38 km. The ridge-transform intersections are marked by deep nodal basins lying on the transform side of the neovolcanic zone that defines the present-day spreading axis. The walls of the transform generally are steep (25?-40?), although locally, they can be more subdued. The deepest point in the transform is 6480 m in the southern nodal basin, and the shallowest is an uplifted wave-cut terrace that exposes plutonic rocks from the deepest layer of the ocean crust at 700 m. The transform valley is bisected by a 1.5-km-high median tectonic ridge that extends from the northern ridge-transform intersection to the midpoint of the active transform. The seismic survey showed that the floor of the transform contains up to 0.5 km of sediment. Piston-coring at two locations on the transform floor recovered more than 1 m of sand and gravel, which appears to be turbidites shed from the walls of the fracture zone. Extensive dredging showed that more than two-thirds of the crust exposed in the transform valley and its walls were plutonic rocks, principally gabbros and residual mantle peridotites. In contrast, based on dredging and seafloor morphology, only relatively undisrupted pillow basalt flows have been exposed on crust of the same age spreading away from the transform. Magnetic anomalies are well defined out to 11 m.y. over the flanking transverse ridges and transform valley, even where layer 2 appears to be absent. The total opening rate is 1.6 cm/yr, but the arrangement of the anomalies indicates that the spreading for each ridge is asymmetric, with the ridge flanks facing the transform spreading at a rate of 1.0 cm/yr. Such an asymmetric spreading pattern requires that both the northern and southern ridges migrate away from each other at 0.2 cm/yr, thus lengthening the transform at 0.4 cm/yr for the last 11 m.y. To the north, the fracture zone valley is oriented differently from the present-day transform, indicating a paleospreading direction change at 17 m.y. from N10?E to due north-south. This change placed the transform into extension for the 11-m.y. period required for simple orthogonal ridge-transform geometry to be reestablished and produced a large transtensional basin within the transform valley. This basin was split by continued transform slip after 11 m.y., with the larger half moving to the north with the African Plate.
Language	English
Dates of publication	1991-9999
Size	Online-Ressource
Publisher	PANGAEA - Data Publisher for Earth & Environmental Science
Publishing place	Bremen/Bremerhaven
Document type	Book ; Conference proceedings ; Online
Note	This dataset is supplement to doi:10.2973/odp.proc.sr.118.156.1991
DOI	10.1594/PANGAEA.757822
Database	Library catalogue of the German National Library of Science and Technology (TIB), Hannover

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Article: Arc-continent collisions, sediment recycling and the maintenance of the continental crust

Clift, Peter D. / Schouten, Hans A. / Vannucchi, Paola

Abstract: Subduction zones are both the source of most new continental crust and thelocations where crustal material is returned to the upper mantle. Globally the total amount ofcontinental crust and sediment subducted below forearcs currently lies close to 3.0 ... ...

Abstract	Subduction zones are both the source of most new continental crust and thelocations where crustal material is returned to the upper mantle. Globally the total amount ofcontinental crust and sediment subducted below forearcs currently lies close to 3.0 ArmstrongUnits (1 AU = 1 km3/yr), of which 1.65 AU comprises subducted sediments and 1.33 AUtectonically eroded forearc crust. This compares with average ~0.4 AU lost duringsubduction of passive margins during Cenozoic continental collision. Individual margins mayretreat in a wholesale, steady-state mode, or in a slower way involving the trenchwarderosion of the forearc coupled with landward underplating, such as seen in the central andnorthern Andean margins. Tephra records of magmatism evolution from Central Americaindicate pulses of recycling through the roots of the arc. While this arc is in a state of long-term mass loss this is achieved in a discontinuous fashion via periods of slow tectonic erosionand even sediment accretion interrupted by catastrophic erosion events, likely caused byseamount subduction. Crustal losses into subduction zones must be balanced by arcmagmatism and we estimate global average melt production rates to be 96 and 64km3/m.y./km in oceanic and continental arc respectively. Key to maintaining the volume ofthe continental crust is the accretion of oceanic arcs to continental passive margins. Massbalancing across the Taiwan collision zones suggests that almost 90% of the colliding LuzonArc crust is accreted to the margin of Asia in that region. Rates of exhumation and sedimentrecycling indicate the complete accretion process spans only 6–8 m.y. Subduction ofsediment in both erosive and inefficient accretionary margins provides a mechanism forreturning continental crust to the upper mantle. Sea level governs rates of continental erosionand thus sediment delivery to trenches, which in turn controls crustal thicknesses over 107–109 yrs. Tectonically thickened crust is reduced to normal values (35–38 km) over timescalesof 100–200 Ma.
Language	English
Document type	Article
Database	AGRIS - International Information System for the Agricultural Sciences and Technology

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Article: Distributed deformation ahead of the Cocos-Nazca Rift at the Galapagos triple junction

Smith, Deborah K. / Schouten, Hans A. / Zhu, Wenlu / Montesi, Laurent G. J. / Cann, Johnson R.

Abstract: HS was supported by the U.S. National Science Foundation(NSF) grant OCE‐0751831, DS by NSF grant OCE‐1028537,WZ by NSF grant EAR‐1056317, and LM by NSF grantEAR‐0911151. ...

Abstract	HS was supported by the U.S. National Science Foundation(NSF) grant OCE‐0751831, DS by NSF grant OCE‐1028537,WZ by NSF grant EAR‐1056317, and LM by NSF grantEAR‐0911151.
Language	en_us
Document type	Article
Database	AGRIS - International Information System for the Agricultural Sciences and Technology

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Article: Arc–continent collision and the formation of continental crust : a new geochemical and isotopic record from the Ordovician Tyrone Igneous Complex, Ireland

Draut, Amy E. / Clift, Peter D. / Amato, Jeffrey M. / Blusztajn, Jerzy S. / Schouten, Hans A.

Abstract: Author Posting. © Geological Society of London, 2009. This is the author's version of the work. It is posted here by permission of Geological Society of London for personal use, not for redistribution. The definitive version was published in Journal of ...

Abstract	Author Posting. © Geological Society of London, 2009. This is the author's version of the work. It is posted here by permission of Geological Society of London for personal use, not for redistribution. The definitive version was published in Journal of the Geological Society 166 (2009): 485-500, doi:10.1144/0016-76492008-102.
Language	English
Document type	Article
Database	AGRIS - International Information System for the Agricultural Sciences and Technology

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Article: Central role of detachment faults in accretion of slow-spreading oceanic lithosphere

Escartin, Javier / Smith, Deborah K. / Cann, Johnson R. / Schouten, Hans A. / Langmuir, Charles H. / Escrig, S.

Abstract: Supported by CNRS (JE), NSF (DKS, HS, JC, CL and SE), WHOI (JE, DKS,HS and JC), Harvard University (JE, CL and SE), Univ. of Leeds (JC), and MIT (JE). ...

Abstract	Supported by CNRS (JE), NSF (DKS, HS, JC, CL and SE), WHOI (JE, DKS,HS and JC), Harvard University (JE, CL and SE), Univ. of Leeds (JC), and MIT (JE).
Language	en_us
Document type	Article
Database	AGRIS - International Information System for the Agricultural Sciences and Technology

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Article: Interplay between faults and lava flows in construction of the upper oceanic crust : the East Pacific Rise crest 9°25′–9°58′N

Escartin, Javier / Soule, Samuel A. / Fornari, Daniel J. / Tivey, Maurice A. / Schouten, Hans A. / Perfit, Michael R.

Abstract: The field and laboratory studies were supportedby NSF grants OCE-9819261 (to H.S., M.A.T., andD.J.F.), OCE-0525863 (D.J.F. and S.A.S.), OCE-0138088(M.P.), WHOI Vetlesen Foundation Funds (J.E., D.J.F., andS.A.S.). Additional support by INSU/CNRS to J.E. ... ...

Abstract	The field and laboratory studies were supportedby NSF grants OCE-9819261 (to H.S., M.A.T., andD.J.F.), OCE-0525863 (D.J.F. and S.A.S.), OCE-0138088(M.P.), WHOI Vetlesen Foundation Funds (J.E., D.J.F., andS.A.S.). Additional support by INSU/CNRS to J.E. is alsoacknowledged.
Language	en_us
Document type	Article
Database	AGRIS - International Information System for the Agricultural Sciences and Technology

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