Generation of sodium-rich magmas from newly underplated basaltic crust

Atherton, M. P.; Petford, Nick

doi:10.1038/362144a0

Cited by 1,174 publications

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“…However, the 60 Ma of age for the subducting slab and the location of these rocks, 300 km inboard of the present trench, suggest that the subducting oceanic crust was too old and cold to melt. Consequently, Atherton and Petford (1993) and Petfort and Atherton (1996) suggested that these rocks were produced by melting of basaltic lower crust. Adakite-like rocks from the South Island, New Zealand (Muir et al, 1995), the Klamath Mountains of California and Oregon (Barnes et al, 1996), the Antarctic Peninsula (Wareham et al, 1997), and the eastern China (Zhang, Q. et al, 2001) were subsequently interpreted as the products of partial melting of mafic lower crust, formed in response to crustal thickening achieved through underplating of mantle-derived mafic magmas.…”

Section: Petrogenetic Model For the Zhantang Adakite-like Andesitic Mmentioning

confidence: 99%

“…Atherton and Petford (1993) have pointed out that Na-rich magmas similar to adakite can also be produced by partial melting of newly underplated basaltic rocks beneath a thickened continental crust. The geochemical features of leucogranites and tonalities from the Cordillera Blanca fits the criteria established for adakite.…”

Section: Petrogenetic Model For the Zhantang Adakite-like Andesitic Mmentioning

confidence: 99%

“…Three petrogenetic models have been proposed for the generation of adakitic magmas: (1) partial melting of subducting slab (e.g., Defant and Drummond, 1990), (2) partial melting of basaltic lower crust (e.g., Atherton and Petford 1993), and (3) fractionation and contamination of mantle-derived magmas with garnet-bearing lower continental crust (e.g., Feeley and Hacker, 1995).…”

Section: Petrogenetic Model For the Zhantang Adakite-like Andesitic Mmentioning

confidence: 99%

“…Like Archean high-Al tonalite-trondhjemitegranodiorite (TTG), modern adakitic rocks are high-Al (>15% Al 2 O 3 at the 70% SiO 2 level), sodic, intermediate to felsic igneous rocks Atherton and Petford 1993). The origin of adakitic (or TTG-like) magmas has been the subject of much discussion (e.g., Drummond and Defant, 1990;Defant and Drummond, 1990;Atherton and Petford 1993;Drummond et al, 1996;Martin, 1999;.…”

Section: Introductionmentioning

confidence: 99%

“…The origin of adakitic (or TTG-like) magmas has been the subject of much discussion (e.g., Drummond and Defant, 1990;Defant and Drummond, 1990;Atherton and Petford 1993;Drummond et al, 1996;Martin, 1999;. These rocks have distinctive geochemical features such as high Sr, low Y and HREE contents and high Sr/Y and La/Yb ratios, suggesting that they are derived from a basaltic source at pressures high enough to stabilize garnet ± amphibole (e.g., Kay, 1978;Martin, 1986; Huichang Basin, Southeastern (SE) China, are extremely high-Na (up to 8.46 wt% Na 2 O), and high-Al trondhjemitic rocks.…”

Section: Introductionmentioning

confidence: 99%

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Extremely high-Na adakite-like magmas derived from alkali-rich basaltic underplate: The Late Cretaceous Zhantang andesites in the Huichang Basin, SE China.

Xiong

et al. 2003

Geochem. J.

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The Zhantang andesites, which erupted in the Late Cretaceous Huichang Basin of SE China interior, were associated with the Late Mesozoic lithospheric extension and basaltic underplating. They are highNa (6.59-8.46 wt% Na 2 O), high-Al trondhjemitic rocks with high Sr and Ba, low Y and HREE, and high Sr/Y and La/Yb ratios, similar to modern adakites. However, they are much higher in Na 2 O but lower in CaO than adakites. Their εNd(T) values of -2.3 to -3.8 and initial 87 Sr/ 86 Sr ratios of 0.707 to 0.708 are also significantly different from those of adakites with MORB-like isotopic compositions. These chemical and isotopic features, along with the tectonic setting, suggest that they were not produced by partial melting of subducting slab.The Zhantang adakite-like magmas may be derived from underplated basaltic lower crust, but require a compositionally peculiar basaltic protolith to account for their extremely high-Na and low-Ca feature. They are compositionally comparable to the experimentally produced partial melts of alkali-rich basalt. We therefore interpret them as the products of melting of an alkali-rich basaltic rock.

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Section: Petrogenetic Model For the Zhantang Adakite-like Andesitic Mmentioning

confidence: 99%

Section: Petrogenetic Model For the Zhantang Adakite-like Andesitic Mmentioning

confidence: 99%

Section: Petrogenetic Model For the Zhantang Adakite-like Andesitic Mmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Extremely high-Na adakite-like magmas derived from alkali-rich basaltic underplate: The Late Cretaceous Zhantang andesites in the Huichang Basin, SE China.

Xiong

et al. 2003

Geochem. J.

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Rock uplift and exhumation of continental margins by the collision, accretion, and subduction of buoyant and topographically prominent oceanic crust

Spikings

Simpson

2014

Tectonics

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Understanding the causes of rock and surface uplift is important because they control the location of mountain building, depocenters, and drainage characteristics and can influence climate. Here we combine previous thermochronological data with field observations to determine the amount of exhumation, rock, and surface uplift that occurs in the upper plate of Central and South American subduction zones during the collision, accretion, and subduction of oceanic plateaus and aseismic ridges. The collision of buoyant and topographically prominent oceanic plateaus and ridges can drive at least 5 km of rock uplift within 2 Ma. Uplift appears to be an immediate response to collision and is generally independent of the slab dip. The amount of rock uplift is controlled mainly by excess topography associated with the ridge (ultimately linked to buoyancy) and erosion, while it is also influenced by the strength of the subduction interface related to the presence of volcanic asperities and overpressured sediments in the subduction channel. The quantity of exhumation is strongly dependant on climate-induced erosion and the lifespan over which the topography is uplifted and supported. Sediment draining into the trench may leave the elevated ridge axis sediment starved, increasing the shear stresses at the ridge subduction interface, leading to positive feedback between ridge subduction, rock uplift, and exhumation. Trench-parallel variations in exhumation have a direct impact on exploration paradigms for porphyry-related metalliferous deposits, and it is likely that porphyry systems are completely eroded by the impingement of plateaus and aseismic ridges within temperate and tropical climates.

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Eocene adakitic porphyries in the central‐northern Qiangtang Block, central Tibet: Partial melting of thickened lower crust and implications for initial surface uplifting of the plateau

Wang

Wyman

et al. 2017

JGR Solid Earth

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The time and mechanism of crustal thickening and initial surface uplift of the Tibetan Plateau remain highly controversial. Here we report on zircon U‐Pb age, and mineral, element, and Sr‐Nd isotope composition data for Eocene adakitic porphyries in the Laorite Co area of central‐northern Qiangtang Block, central Tibet. Laser ablation‐inductively coupled plasma‐mass spectrometry zircon U‐Pb age dating shows that the porphyries were generated at 42–41 Ma. All samples display adakitic geochemical characteristics, such as high SiO2 and Al2O3, and low Y and Yb contents, and high Sr/Y and La/Yb ratios with positive Sr and negligible Eu anomalies and Nb‐Ta depletion. They also have low magnesium number (Mg #) (16–45) and high K2O (4.0–4.6 wt %) values, as well as high (87Sr/86Sr)i (0.7076–0.7080) and low εNd(t) (−5.9 to −4.4) values. These adakitic rocks were most probably generated by partial melting of thickened lower crust in the stability field of garnet, amphibole, and rutile but with relatively minor plagioclase. Moreover, such a crustal thickening process beneath this block likely occurred no later than the middle Eocene and was most probably caused by the southward subduction of the Songpan‐Ganzi Block in the early Cenozoic. In addition, the occurrences of exposed adakitic porphyries unambiguously indicate that exhumation process occurred after their formation. Thus, these ~42 Ma adakitic porphyries indicate the occurrence of significant exhumation since 42 Ma. Integrated with the thermochronological and paleoelevation data, we suggest that the initial surface uplift of the Qiangtang Block, triggered by crustal thickening, was underway by the middle Eocene (~42 Ma).

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Generation of sodium-rich magmas from newly underplated basaltic crust

Cited by 1,174 publications

References 30 publications

Extremely high-Na adakite-like magmas derived from alkali-rich basaltic underplate: The Late Cretaceous Zhantang andesites in the Huichang Basin, SE China.

Extremely high-Na adakite-like magmas derived from alkali-rich basaltic underplate: The Late Cretaceous Zhantang andesites in the Huichang Basin, SE China.

Rock uplift and exhumation of continental margins by the collision, accretion, and subduction of buoyant and topographically prominent oceanic crust

Eocene adakitic porphyries in the central‐northern Qiangtang Block, central Tibet: Partial melting of thickened lower crust and implications for initial surface uplifting of the plateau

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