Sur-Nacimiento Fault Zone of California: Continental Margin Tectonics

Page, Benjamin M.

doi:10.1130/0016-7606(1970)81[667:sfzocc]2.0.co;2

Cited by 84 publications

(72 citation statements)

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“…Since the Pilarcitos fault separates granitic basement terrain of the Salinian block from the Franciscan Formation (Page, 1970), a magnetic signature might be expected at the boundary, due to the abundance of basalt within the Franciscan Formation onshore (Darrow, 1963). A western boundary for small magnetic anomalies is suggested in the total intensity magnetic map covering the area west of the Golden Gate (Fig.…”

Section: Pilarcitos Faultmentioning

confidence: 99%

“…Basement in this block consists of granitic and high grade metamorphic rocks. Page (1970) suggests that the offshore extension of the Sur-Nacimiento fault, which lies on the continental slope west of the Farallon Islands, is the approximate boundary between the sialic rocks of the Salinian block and the eugeosynclinal type rocks of the Franciscan assemblage. The easternmost contact of granitic rocks and the Franciscan Formation is generally the San Andreas fault; however,-locally the Pilarcitos fault forms the boundary (Fig.…”

mentioning

confidence: 99%

“…The magnetic data was useful in detecting susceptibility changes at fault boundaries. CHAPTER II REGIONAL STRUCTURAL FRAMEWORK Compton (1966) and Page (1970) indicate that the continental shelf off San Francisco lies within the boundaries of the Salinian block which extends from the Transverse Ranges, 375 km south, to Point Arena, 140 km north. Basement in this block consists of granitic and high grade metamorphic rocks.…”

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Structure of the continental shelf west of San Francisco, California

Cooper¹

1973

Open-File Report

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Section: Pilarcitos Faultmentioning

confidence: 99%

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Structure of the continental shelf west of San Francisco, California

Cooper¹

1973

Open-File Report

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“…There, amphibolite-granulite facies gneiss and schist lacking pure quartzite and carbonate rocks characteristic of the North American margin (Ross 1977) are cut by 100-82 Ma plutons ranging in composition from gabbro to granodiorite (Mattinson 1978(Mattinson , 1990Kistler and Champion 2001;Kidder et al 2003;Chapman et al 2014), which is similar to the setting and magmatism of slab failure sectors in the other batholiths. Thus, the Salinian block appears to be missing its western arc component (Page 1970(Page , 1982 and, with 100-82 Ma magmatism, appears to represent the slab failure half of a Cordilleran batholith, which makes it a reasonable candidate for the exhumed eastern half of the Coastal batholith of Peru with its Arequipa-Antofalla basement (Loewy et al 2004). In fact, paleomagnetic data from Upper Cretaceous and Paleocene sedimentary rocks of the Salinian block indicate that they were deposited 2800-2100 ± 500 km south of their present location (Champion et al 1984), although there is some controversy about the data based on study of different rocks (Whidden et al 1998).…”

Section: Discussionmentioning

confidence: 99%

Arc and Slab-Failure Magmatism in Cordilleran Batholiths I – The Cretaceous Coastal Batholith of Peru and its Role in South American Orogenesis and Hemispheric Subduction Flip

Hildebrand¹,

Whalen

2014

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We examined the temporal and spatial relations of rock units within the Western Cordillera of Peru where two Cretaceous basins, the Huarmey-Cañete and the West Peruvian Trough, were considered by previous workers to represent western and eastern parts respectively of the same marginal basin. The Huarmey-Cañete Trough, which sits on Mesoproterozoic basement of the Arequipa block, was filled with up to 9 km of Tithonian to Albian tholeiitic–calc-alkaline volcanic and volcaniclastic rocks. It shoaled to subaerial eastward. At 105–101 Ma the rocks were tightly folded and intruded during and just after the deformation by a suite of 103 ± 2 Ma mafic intrusions, and later in the interval 94–82 Ma by probable subduction-related plutons of the Coastal batholith. The West Peruvian Trough, which sits on Paleozoic metamorphic basement, comprised a west-facing siliciclastic-carbonate platform and adjacent basin filled with up to 5 km of sandstone, shale, marl and thinly bedded limestone deposited continuously throughout the Cretaceous. Rocks of the West Peruvian Trough were detached from their basement, folded and thrust eastward during the Late Cretaceous–Early Tertiary. Because the facies and facing directions of the two basins are incompatible, and their development and subjacent basements also distinct, the two basins could not have developed adjacent to one another. Based on thickness, composition and magmatic style, we interpret the magmatism of the Huarmey-Cañete Trough to represent a magmatic arc that shut down at about 105 Ma when the arc collided with an unknown terrane. We relate subsequent magmatism of the early 103 ± 2 Ma syntectonic mafic intrusions and dyke swarms to slab failure. The Huarmey-Cañete-Coastal batholithic block and its Mesoproterozoic basement remained offshore until 77 ± 5 Ma when it collided with, and was emplaced upon, the partially subducted western margin of South America to form the east-vergent Marañon fold–thrust belt. A major pulse of 73–62 Ma plutonism and dyke emplacement followed terminal collision and is interpreted to have been related to slab failure of the west-dipping South American lithosphere. Magmatism, 53 Ma and younger, followed terminal collision and was generated by eastward subduction of Pacific oceanic lithosphere beneath South America. Similar spatial and temporal relations exist over the length of both Americas and represent the terminal collision of an arc-bearing ribbon continent with the Americas during the Late Cretaceous–Early Tertiary Laramide event. It thus separated long-standing westward subduction from the younger period of eastward subduction characteristic of today. We speculate that the Cordilleran Ribbon Continent formed during the Mesozoic over a major zone of downwelling between Tuzo and Jason along the boundary of Panthalassic and Pacific oceanic plates.SOMMAIRENous avons étudié les relations spatiales et temporales des unités de roches dans la portion ouest de la Cordillère du Pérou, où deux bassins crétacés, la fosse d’accumulation de Huarmey-Cañete et la fosse d’accumulation péruvienne de l’ouest, ont été perçues par des auteurs précédents comme les portions ouest et est d’un même bassin de marge. La fosse de Huarmey-Cañete, qui repose sur le socle mésoprotérozoïque du bloc d’Arequipa, a été comblée par des couches de roches volcaniques tholéitiques – calco-alcalines de l’Albien au Thithonien atteignant 9 km d’épaisseur. Vers l’est, l’ensemble a fini par former des hauts fonds. Vers 105 à 101 Ma, les roches ont été plissées fortement puis recoupées par une suite d’intrusions vers 103 ± 2 Ma, durant et juste après la déformation, et plus tard dans l’intervalle 94 – 82 Ma, probablement par des plutons de subduction du batholite côtier. Quant à la fosse d’accumulation péruvienne de l’ouest, elle repose sur un socle métamorphique paléozoïque, et elle est constituée d’une plateforme silicoclastique – carbonate à pente ouest et d’un bassin contigu comblé par des grès, des schistes, des marnes et des calcaires finement laminés atteignant 5 km d’épaisseur et qui se sont déposés en continu durant tout le Crétacé. Les roches de la fosse d’accumulation péruvienne de l’ouest ont été décollées de leur socle, plissées et charriées vers l’est durant la fin du Crétacé et le début du Tertiaire. Parce que les facies et les profondeurs de sédimentation de ces deux fosses d’accumulation dont incompatibles, et que leur développement et leur socle sont différents, ces deux fosses ne peuvent pas s’être développées côte à côte. À cause de l’épaisseur accumulée, de sa composition et du style de son magmatisme, nous pensons que la fosse d’accumulation de Huarmey-Cañete représente un arc magmatique qui s’est éteinte vers 105 Ma, lorsque l’arc est entré en collision avec un terrane inconnu. Nous pensons que le magmatisme subséquent aux premières intrusions mafiques syntectoniques et aux réseaux de dykes de 103 ± 2 Ma sont à mettre au compte d’une rupture de plaque. Le bloc Huarmey-Cañete-batholitique côtier et son socle mésoprotérozoïque sont demeurés au large jusqu’à 77 ± 5 Ma, moment où il est entré en collision et a été poussé par-dessus la marge ouest sud-américaine partiellement subduite, pour ainsi former la zone de chevauchement de vergence est de Marañon. Nous croyons que la séquence majeure de plutonisme et d’intrusion de dykes qui a succédé à la collision finale à 73–62 Ma doit être reliée à une rupture de la plaque lithosphérique sud-américaine à pendage ouest. Le magmatisme de 53 Ma et plus récent qui a succédé à la collision finale, a été généré par la subduction vers l’est de la lithosphère océanique du Pacifique sous l’Amérique du Sud. Des relations temporelles et spatiales similaires qui existent tout le long des deux Amériques représentent la collision terminale d’un ruban continental d’arcs avec les Amériques durant la phase tectonique laramienne de la fin du Crétacé–début du Tertiaire. Elle a donc séparé la subduction vers l’ouest de longue date de la période de subduction vers l’est plus jeune caractérisant la situation actuelle. Nous considérons que le ruban continental de la Cordillère s’est constitué durant le Mésozoïque au-dessus d’une zone majeure de convection descendante entre Tuzo et Jason, le long de la limite entre les plaques océaniques Panthalassique et Pacifique.

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“…The problem is complex, and it has been reviewed recently by Scholl et al [1970]. The blueschists of the California Coast Ranges have been interpreted in terms of underflow of the Pacific mantle plate along a Benioff zone during the Mesozoic by Hamilton [1969] and Ernst [1970]; see also Page [1970]. Gresens [1970] accepted underthrusting for this region, but he interpreted the blueschists as metastable rocks formed by fluids generated during serpentinization.…”

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confidence: 99%

Petrologic aspects of plate tectonics

Wyllie

1971

EoS Transactions

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The concept of plate tectonics has developed during the past four years from the hypotheses of continental drift and sea‐floor spreading, supported by a variety of evidence from paleomagnetism, geochronology, and marine geology and geophysics. A series of four contiguous papers in the March 1968 issue of the Journal of Geophysical Research correlated on a global scale the linear magnetic anomalies, which are parallel to and bilaterally symmetrical about the oceanic ridge system, with the polarity reversals of the earth's magnetic field imprinted on new oceanic crust as it was generated at the oceanic ridge crests [Pitman et al., 1968; Dickson et al., 1968; Le Pichon and Heirtzler, 1968; Heirtzler et al., 1968]. In 1967 and 1968, four major papers introduced plate tectonics: the earth's surface is considered to be made up of a few rigid crustal plates or blocks in motion relative to each other [McKenzie and Parker, 1967; Morgan, 1968; Le Pichon, 1968; Isacks et al., 1968].

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Sur-Nacimiento Fault Zone of California: Continental Margin Tectonics

Cited by 84 publications

References 0 publications

Structure of the continental shelf west of San Francisco, California

Structure of the continental shelf west of San Francisco, California

Arc and Slab-Failure Magmatism in Cordilleran Batholiths I – The Cretaceous Coastal Batholith of Peru and its Role in South American Orogenesis and Hemispheric Subduction Flip

Petrologic aspects of plate tectonics

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