Generation and evolution of magma beneath the East Pacific Rise: Constraints from U-series disequilibrium and plagioclase-hosted melt inclusions

Zhang, Guo Liang; Zeng, Zhongming; Beier, Christoph; Yin, Xue; Turner, Simon

doi:10.1016/j.jvolgeores.2010.03.002

Cited by 14 publications

(9 citation statements)

References 82 publications

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“…According to geochemical data for major elements and some trace elements of the basalts sampled at the seamounts and the islands of previous studies [ Tu et al ., ; Yan et al ., ; Li et al ., ], this study calculated the density of the basalts sampled at adjacent Daimao, Xianbei, Zhangzhong and Zhenbei seamounts using the method proposed by Zhang et al . [] (Figure ). Generally, we can see these density values largely distributed on both sides of 2.65 g/cm 3 , which we assign as the buried magmatic seamounts in the gravity model.…”

Section: Crustal Structure On the Northwestern Margin Of The South Chsupporting

confidence: 89%

“…Densities are derived from the geochemical data for major elements and some trace elements of the basalts sampled at the seamounts (such as Daimao, Xianbei, Zhangzhong, and Zhenbei) of previous studies [ Tu et al ., ; Yan et al ., ; Li et al ., ] using the calculated method proposed by Zhang et al . []. Generally, these density values evenly distribute on both sides of 2.65 g/cm 3 .…”

Section: Crustal Structure On the Northwestern Margin Of The South Chmentioning

confidence: 92%

“…But to the east, the crustal thickness along profile ESP-W, which crossed the coast line, the PRMB (including the structural units of NFT, Zhu III D, SHASR, Zhu II D and SR) and the QDNB (including CCS), did not decrease monotonically from the continent to the oceanic basin. Rather, the crustal thickness changes from 28-30 km under the coast line, to 15 km below the Zhu III D, to 21-24 km Densities are derived from the geochemical data for major elements and some trace elements of the basalts sampled at the seamounts (such as Daimao, Xianbei, Zhangzhong, and Zhenbei) of previous studies [Tu et al, 1992;Yan et al, 2008;Li et al, 1991] using the calculated method proposed by Zhang et al [2010]. Generally, these density values evenly distribute on both sides of 2.65 g/cm 3 .…”

Section: Crustal Thinningmentioning

confidence: 99%

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Crustal structure and extension mode in the northwestern margin of the South China Sea

Gao

McIntosh

et al. 2016

Geochem Geophys Geosyst

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Combining multi‐channel seismic reflection and gravity modeling, this study has investigated the crustal structure of the northwestern South China Sea margin. These data constrain a hyper‐extended crustal area bounded by basin‐bounding faults corresponding to an aborted rift below the Xisha Trough with a subparallel fossil ridge in the adjacent Northwest Sub‐basin. The thinnest crust is located in the Xisha Trough, where it is remnant lower crust with a thickness of less than 3 km. Gravity modeling also revealed a hyper‐extended crust across the Xisha Trough. The postrift magmatism is well developed and more active in the Xisha Trough and farther southeast than on the northwestern continental margin of the South China Sea; and the magmatic intrusion/extrusion was relatively active during the rifting of Xisha Trough and the Northwest Sub‐basin. A narrow continent‐ocean transition zone with a width of ∼65 km bounded seaward by a volcanic buried seamount is characterized by crustal thinning, rift depression, low gravity anomaly and the termination of the break‐up unconformity seismic reflection. The aborted rift near the continental margin means that there may be no obvious detachment fault like that in the Iberia‐Newfoundland type margin. The symmetric rift, extreme hyper‐extended continental crust and hotter mantle materials indicate that continental crust underwent stretching phase (pure‐shear deformation), thinning phase and breakup followed by onset of seafloor spreading and the mantle‐lithosphere may break up before crustal‐necking in the northwestern South China Sea margin.

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Section: Crustal Structure On the Northwestern Margin Of The South Chsupporting

confidence: 89%

Section: Crustal Structure On the Northwestern Margin Of The South Chmentioning

confidence: 92%

Section: Crustal Thinningmentioning

confidence: 99%

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Crustal structure and extension mode in the northwestern margin of the South China Sea

Gao

McIntosh

et al. 2016

Geochem Geophys Geosyst

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“…The sample pretreatment procedures and testing methods have been described by G. L. Zhang, Zeng, Beier, Yin, and Turner (2010). The sample pretreatment procedures and testing methods have been described by G. L. Zhang, Zeng, Beier, Yin, and Turner (2010).…”

Section: Methodsmentioning

confidence: 99%

Petrology and mineralogy of pumice from the Iheya North Knoll, Okinawa Trough: Implications for the differentiation of crystal‐poor and volatile‐rich melts in the magma chamber

et al. 2018

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The Iheya North Knoll is a submarine hill that is covered with pumice in the Okinawa Trough. The petrology and mineralogy of the crystal‐poor rhyolitic pumice collected from two sampling sites (T3 and T6) on the knoll were analysed in this article. The T6 pumice, which contains some mafic minerals (e.g., clinopyroxene, orthopyroxene), is slightly more crystal‐rich (<5 vol.%) than the T3 pumice (<2 vol.%). However, both types of pumice are high‐potassium rhyolites with similar Nd isotopic ratios and rare earth element patterns, as well as similar glass compositions, which indicates that they may fall along a line of descent of comagmatic evolution. The T6 pumice contains some xenomorphic clinopyroxenes that are not in equilibrium with their whole‐rock composition, which suggests that the crystal‐poor melt was extracted from a more mafic source. The T3 pumice features a flow structure, and its matrix glass records higher Cl concentrations and a lower total mass than the T6 pumice, which implies that the T3 melt has a higher volatile content and lower viscosity. The distinct petrographic characteristics but similar matrix glass compositions of the T3 and T6 pumice suggest that the extracted melt was physically differentiated during ascent, with the more crystal‐poor and volatile‐rich T3 melt reaching a higher lever in the magma chamber. Meanwhile, simulation calculations indicate that the melt experienced near‐adiabatic decompression‐driven chemical differentiation, which led to the growth of sodium‐rich plagioclase but not quartz in the pumice.

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“…Thus, to the extent that the phenocrysts crystallized from a less evolved or less well-mixed melt, the melt inclusions record the nature of more primitive melt compositions. Studies of melt inclusions have revealed that, although they are broadly similar in major element composition to their host lavas, they tend to extend to more primitive (higher MgO) compositions, suggesting that they indeed record an earlier point in the evolutionary history of the magma (e.g., Nielsen et al, 1995;Shimizu, 1998;Sinton et al, 1993;Sobolev and Shimizu, 1993;Sours-Page et al, 1999Zhang et al, 2010). Maclennan (2008) found that melt inclusions in Icelandic lavas were more heterogeneous than whole-rock samples of the same flow.…”

mentioning

confidence: 99%

Composition of the Oceanic Crust

White

Klein²

2014

Treatise on Geochemistry

195

160

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Generation and evolution of magma beneath the East Pacific Rise: Constraints from U-series disequilibrium and plagioclase-hosted melt inclusions

Cited by 14 publications

References 82 publications

Crustal structure and extension mode in the northwestern margin of the South China Sea

Crustal structure and extension mode in the northwestern margin of the South China Sea

Petrology and mineralogy of pumice from the Iheya North Knoll, Okinawa Trough: Implications for the differentiation of crystal‐poor and volatile‐rich melts in the magma chamber

Composition of the Oceanic Crust

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