Evidence for late Proterozoic subduction from 700-Myr-old blueschists in China

Nakajima, Terumasa; Maruyama, S.; Uchiumi, Shigeru; Liou, J. G.; Wang, X.; Xiao, Xia; Graham, S.A.

doi:10.1038/346263a0

Cited by 117 publications

(44 citation statements)

References 16 publications

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“…900 Ma Aksu blueschists and granitic gneisses of ca. 900 Ma (Nakajima et al 1990;Wang et al 1990;Xiao et al 1992;Che et al 1994;Chen et al 2000b). Late Sinian (about 800 Ma) tillites occurring widespread in the northern margin of the Tarim plate, the north and south of the Yili plate and the Kazakhstan plate Mikolaichuk et al 1997) indicate that the Kazakhstan (North Tien Shan)-Yili, the Central Tianshan and Tarim plates were part of the 'Rodinia supercontinent' throughout the latest Proterozoic (Xu et al 2005).…”

Section: Implications For the Tectonic Evolution Of The South Tianshamentioning

confidence: 94%

“…Permian fluvial deposits and rift-type volcanics unconformably overlie the earlier strata (Carroll et al 1995). Granitic gneisses with a U-Pb zircon age of 707 ± 13 Ma and a Sm-Nd model age of 1.9 Ga (Chen et al 2000a) and blueschist-facies meta-pelites with Rb-Sr isochron and K-Ar ages of about 700 Ma (Nakajima et al 1990) are exposed in the northwestern margin of the Tarim basin. Granulite xenoliths from the Cretaceous Tuoyun basalts exhibit LA-ICPMS U-Pb zircon ages of 690-770 Ma and Hf model ages of 1.3-1.7 Ga (Zheng et al 2006a, b).…”

Section: Regional Geologymentioning

confidence: 97%

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Tectonic evolution of the South Tianshan orogen and adjacent regions, NW China: geochemical and age constraints of granitoid rocks

Gao

Long

Klemd

et al. 2008

Int J Earth Sci (Geol Rundsch)

530

407

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Section: Implications For the Tectonic Evolution Of The South Tianshamentioning

confidence: 94%

Section: Regional Geologymentioning

confidence: 97%

Tectonic evolution of the South Tianshan orogen and adjacent regions, NW China: geochemical and age constraints of granitoid rocks

Gao

Long

Klemd

et al. 2008

Int J Earth Sci (Geol Rundsch)

530

407

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“…A plot of the P-T conditions of regional metamorphic belts over the world since the Archean shows that the first appearance of blueschist was ca. 700 Ma (Nakajima et al, 1990), and subduction zone rapidly changed cooler at the onset of Phanerozoic ( Fig. 9a; Maruyama et al, 1996;Maruyama and Liou, 1998).…”

Section: Rapid Decrease Of Sea-level During the Neoproterozoicmentioning

confidence: 96%

The naked planet Earth: Most essential pre-requisite for the origin and evolution of life

Maruyama

Ikoma

Genda

et al. 2013

Geoscience Frontiers

Self Cite

126

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a b s t r a c tOur blue planet Earth has long been regarded to carry full of nutrients for hosting life since the birth of the planet. Here we speculate the processes that led to the birth of early life on Earth and its aftermath, finally leading to the evolution of metazoans. We evaluate: (1) the source of nutrients, (2) the chemistry of primordial ocean, (3) the initial mass of ocean, and (4) the size of planet. Among the life-building nutrients, phosphorus and potassium play a key role. Only three types of rocks can serve as an adequate source of nutrients: (a) continent-forming TTG (granite), enabling the evolution of primitive life to metazoans; (b) primordial continents carrying anorthosite with KREEP (Potassium, Rare Earth Elements, and Phosphorus) basalts, which is a key to bear life; (c) carbonatite magma, enriched in radiogenic elements such as U and Th, which can cause mutation to speed up evolution and promote the birth of new species in continental rift settings. The second important factor is ocean chemistry. The primordial ocean was extremely acidic (pH ¼ 1e2) and enriched in halogens (Cl, F and others), S, N and metallic elements (Cd, Cu, Zn, and others), inhibiting the birth of life. Plate tectonics cleaned up these elements which interfered with RNA. Blue ocean finally appeared in the Phanerozoic with pH ¼ 7 through extensive interaction with surface continental crust by weathering, erosion and transportation into ocean. The initial ocean mass was also important. The birth of life and aftermath of evolution was possible in the habitable zone with 3e5 km deep ocean which was able to supply sufficient nutrients. Without a huge landmass, nutrients cannot be supplied into the ocean only by ridge-hydrothermal circulation in the Hadean. Finally, the size of the planet plays a crucial role. Cooling of massive planets is less efficient than smaller ones, so that return-flow of seawater into mantle does not occur until central stars finish their main sequence. Due to the suitable size of Earth, the dawn of Phanerozoic witnessed the initiation of return-flow of seawater into the mantle, leading to the emergence of huge landmass above sea-level, and the distribution of nutrients on a global scale. Oxygen pump also played a critical role to keep high-PO 2 in atmosphere since then, leading to the emergence of ozone layer and enabling animals and plants to invade the land.To satisfy the tight conditions to make the Earth habitable, the formation mechanism of primordial Earth is an important factor. At first, a 'dry Earth' must be made through giant impact, followed by magma ocean to float nutrient-enriched primordial continents (anorthosite þ KREEP). Late bombardment from asteroid belt supplied water to make 3e5 km thick ocean, and not from icy meteorites from Geoscience Frontiers 4 (2013) 141e165Kuiper belt beyond cool Jupiter. It was essential to meet the above conditions that enabled the Earth as a habitable planet with evolved life forms. The tight constraints that we evaluate for birth and evolution of l...

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“…Near Aksu in the southernmost Tian Shan, Precambrian blueschist was recognized, which is unconformably overlain by a Neoproterozoic passivecontinental-margin sequence (Liou et al, 1989;Nakajima et al, 1990). Liou et al (1996) speculate the Aksu blueschist Table 6 Analytical data of 40 Ar/ 39 Ar thermochronologic analysis of hornblende for sample G-3…”

Section: Precambrian Geologymentioning

confidence: 99%

Geochronology and geochemistry of deep-drill-core samples from the basement of the central Tarim basin

Guo

Yin

Robinson

et al. 2005

Journal of Asian Earth Sciences

175

114

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The Tarim basin between the Tibetan plateau to the south and Tian Shan to the north in the Indo-Asian collision zone is little deformed as indicated by flat-lying Cenozoic strata across much of the basin. Due to the lack of direct observations from its crystalline basement, the geologic setting for the existence of such a rigid Cenozoic block remains elusive. Hypotheses for the nature of the Tarim basement include (1) Precambrian basement, (2) late Paleozoic trapped oceanic basin, (3) a late Precambrian failed rift, and (4) a Precambrian oceanic plateau. These models make specific predictions about the age and composition of the Tarim basement. To test these hypotheses, we conduct geochemical and geochronologic analyses of samples recovered from a deep well that reached a depth of . 7000 m and drilled into the crystalline basement for , 35 m beneath the central Tarim basin. Mineralogical composition and major element analysis suggest that the crystalline from the drill core is a diorite. Under think sections the rocks samples consist of fine-grained (0.1-0.4 mm in the longest dimension) and medium-grain domains (2 -3 mm in the longest dimension). The contact between the two domains is sharp and the change in grain size across the boundary is abrupt. The rock under thin section shows undeformed igneous textures. Rare earth element patterns and isotopic compositions of Sr and Nd suggest that the central Tarim diorite was derived from an arc setting. The minimum age of the diorite is determined by 40 Ar/ 39 Ar dating of hornblende, which yields three ages from three different samples: 790.0^22.1, 754.4^22.6, and 744.0^9.3 Ma, respectively (uncertainty is reported at 1s). The older age is associated with the fine-grained sample while the younger ages are associated with the medium-grained samples. We are unable to determine whether the different ages are due to argon loss as the rock was located in partial retention zone or caused by different phases of igneous intrusion. In any case, the initiation of the pluton intrusion in the central Tarim region must predate 790.0^22.1 Ma. The possible existence of a Proterozoic magmatic arc (. 790 Ma) in the central Tarim region may be spatially correlated to a late Precambrian blueschist belt in the southern Tian Shan and a 970-920 Ma plutonic belt in the central and eastern Altyn Tagh range east and west of the drilling site where our samples were obtained. This regional correlation implies the existence of an east-trending Precambrian subduction system underneath the Tarim basin, which might be related to a north-dipping subduction zone. Our new data do not support the Tarim to be floored by a remnant oceanic basin or an oceanic plateau. Our results in conjunction with the fact that the Tarim interior has experienced major deformation as recent as the Jurassic do not support the hypotheses that the Tarim basement is compositionally different from and mechanically stronger than its surrounding areas during Cenozoic deformation. Differences in thermal structures or stress stat...

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Evidence for late Proterozoic subduction from 700-Myr-old blueschists in China

Cited by 117 publications

References 16 publications

Tectonic evolution of the South Tianshan orogen and adjacent regions, NW China: geochemical and age constraints of granitoid rocks

Tectonic evolution of the South Tianshan orogen and adjacent regions, NW China: geochemical and age constraints of granitoid rocks

The naked planet Earth: Most essential pre-requisite for the origin and evolution of life

Geochronology and geochemistry of deep-drill-core samples from the basement of the central Tarim basin

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