Mantle Potential Temperature Estimates and Primary Melt Compositions of the Low-Ti Emeishan Flood Basalt

Shellnutt, J. Gregory; Pham, Thuy Thanh

doi:10.3389/feart.2018.00067

Cited by 27 publications

(15 citation statements)

References 104 publications

(157 reference statements)

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“…Temperatures. The primary melt composition refers to the partial melts that equilibrate with the source rocks, which can be used to constrain the thermal state of the mantle source and the source lithology [42,[51][52][53][54][55][56][57][58]. The magmatic rocks usually undergo variable crystallization and assimila-tion, which modify the composition of the primary melts.…”

Section: Primary Melt Compositions and Mantle Potentialmentioning

confidence: 99%

In Situ Geochemical Compositions of the Minerals in Basaltic Rocks from the West Philippine Basin: Constraints on Source Lithology and Magmatic Processes

et al. 2020

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Since the early Cenozoic, the West Philippine Basin (WPB) and the whole Philippine Sea Plate (PSP) has undergone a complex geological evolution. In this study, we presented K-Ar ages, in situ trace element, and major element compositions of minerals of basalts collected from the Benham Rise and the Central Basin Fault (CBF) in the WPB, to constrain their magmatic process and regional geological evolution. Olivine phenocrysts and microlites in the alkali basalts (20.9 Ma) from the Benham Rise have forsterite (Fo) contents of 56.90%–76.10% and 53.13%-66.41%, respectively. The clinopyroxenes in the tholeiites (29.1 Ma) from the CBF is predominantly diopside and augite, and it is depleted in light rare earth elements (LREEs) (LaN/YbN=0.13–3.40) and large-ion lithophile elements (LILEs). The plagioclases in the basalts from both of the Benham Rise and the CBF are predominantly labradorite and andesine, with a minor amount of bytownite, and it is enriched in LREEs, Ba, Sr, and Pb and exhibits strong positive Eu anomalies. However, there exist obvious differences in plagioclase compositions between these two tectonic sites. The source lithology of the Benham Rise basaltic rocks could be garnet pyroxenite, and yet that of the CBF could be spinel-lherzolite. The calculated mantle potential temperature beneath the Benham Rise is 1439°C–1473°C, which is significantly higher than that beneath the CBF (1345°C–1381°C), suggesting there existed thermal anomaly beneath the Rise during basaltic magmatism. This study also calculated the temperature and pressure of the clinopyroxenes and plagioclases, which have been used to indicate magmatic processes. Finally, we suggest that the Benham Rise basaltic rocks may be related to a mantle plume (e.g., the Oki-Daito mantle plume), and the CBF was once located in a back-arc spreading center behind an active subduction zone. The extinction of the Oki-Daito mantle plume activity might be at about 20.9 Ma, and cessation of the back-arc spreading of WPB was at about 29.1 Ma or younger.

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Section: Primary Melt Compositions and Mantle Potentialmentioning

confidence: 99%

In Situ Geochemical Compositions of the Minerals in Basaltic Rocks from the West Philippine Basin: Constraints on Source Lithology and Magmatic Processes

et al. 2020

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“…Primary melt compositions have been widely used to estimate the thermal state of mantle sources [25,[53][54][55][56][57][58]. The major element data of the late Cenozoic basalts from Thailand have been provided in Yan et al [26].…”

Section: Primary Melt Compositions and The Mantle Potential Temperaturementioning

confidence: 99%

“…%, supposing the olivine-melt distribution coefficient K D (Fe/Mg) Ol/liq = 0.31, Fe 2+ /(Fe 2+ + Fe 3+ ) = 0.9 in the melt (Roder and Emslie, 1970). Melting conditions and mantle potential temperatures (T p ; Table 1) were estimated based on primary melt compositions [18,25,[55][56][57][58][59][60][61].…”

Section: Primary Melt Compositions and The Mantle Potential Temperaturementioning

confidence: 99%

In Situ LA-ICP-MS Analysis of Minerals Hosted by Late Cenozoic Basaltic Rocks from Thailand

et al. 2019

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Shortly after the cessation of seafloor spreading, intraplate magmatism affected large areas in the South China Sea (SCS) region. The origin and geodynamic setting of the post-spreading volcanism is still in debate, for many previous studies have focused on petrogenesis and mantle source of the late Cenozoic basalts from the SCS region. In this study, we obtained in situ major element compositions (by using Electron microprobe analysis—EMPA) and trace element compositions (by using laser ablation inductively coupled plasma mass spectrometry— LA-ICP-MS) for minerals (clinopyroxenes (Cpx), plagioclases (Pl), and olivines (Ol)) hosted by late Cenozoic basaltic rocks from Thailand. The results showed that the olivines had forsterite contents between 60.12% and 84.74%. Clinopyroxene were diopside and augite, and they were enriched in light rare earth elements (LREEs) (LaN/YbN = 1.93–4.27) and depleted in large-ion lithophile elements (LILEs). Mineral compositions (mainly based on clinopyroxene) confirmed that these late Cenozoic basaltic rocks were of an intraplate affinity and were similar to contemporaneous basaltic fields in the SCS region (Southern Vietnam, Northern Hainan, and SCS seamounts). Plagioclases were predominantly labradorite, with a few andesine and bytownite, and they were enriched in LREEs and Ba, Sr, and Pb, and most of them exhibited strong positive Eu anomalies. The source lithology of Thailand basaltic rocks could be garnet pyroxenite. The mantle potential temperature beneath Thailand is in the range of 1448–1467 °C, which can be comparable to those beneath Southern Vietnam and Northern Hainan, indicating the Thailand basaltic rocks could be produced by the Hainan mantle plume. In addition, the crystallization temperature of clinopyroxenes (1145–1214 °C) and plagioclase (1067–1133 °C) and their composition characteristics indicate that the magmatic processes have a conspicuous characteristic of fast rate of magma upwelling. Thus, we proposed that the deep geodynamic setting of Thailand late Cenozoic basaltic rocks is similar to those of the whole SCS region, and Hainan mantle plume plays a significant role in the petrogenesis of these basaltic rocks.

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“…It suggests that a crystallization temperature of 1399AE20°C for the Iceland volcanic rocks corresponds to a mantle potential temperature of *1500°C. Similarly, Al-in-olivine crystallization temperature of 1440°C for Emeishan LIP (Xu and Liu 2016) corresponds to a mantle potential temperature [1500°C (Shellnutt and Pham 2018). Therefore, the estimated maximum crystallization temperature 1484°C for the studied ultramafic rocks can be extrapolated to a mantle potential Different tectonic fields for cumulate and non-cumulate mafic-ultramafic rocks are taken from Beard (1986).…”

Section: Evidence From Crystallization and Mantle Potential Temperaturesmentioning

confidence: 99%

Paleoproterozoic ($$\sim$$1.88–1.89 Ga) ultramafic–mafic sills, Cuddapah basin, India—revisited: Implications for interaction between mantle plume and metasomatized subcontinental lithospheric mantle

2019

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A number of mafic-ultramafic sills, which are supposed to be part of the widespread *1.88-1.89 Ga Hampi-Bastanar Large Igneous Province of the Indian shield, are reported to intrude into sedimentary/ meta-sedimentary rocks of the Proterozoic Cuddapah basin. Mineral chemistry of chrome-spinel, olivine and pyroxene from the cumulate ultramafic rocks of the Pulivendla sills, emplaced at the base of Tadpatri Formation of the Cuddpaha basin, is presented for better understanding on their nature and genesis. The intermediate Cr#, low Mg#, high Fe 3+ # and Ti (apfu) coupled with relatively low Al (apfu) content of studied spinel indicate their Alaskan-type nature. Moreover, the Ca-rich clinopyroxene together with classic variations of Al 2 O 3 , TiO 2 and SiO 2 follow the trend of arc type of intrusions. The calculated Al 2 O 3 content of parental melt of the studied rocks also suggests arc-type characteristics. Whole-rock geochemistry show fractionated chondrite-normalized REE patterns, higher Ba/Nb and low Nb/La that suggest contribution from an enriched mantle source, whereas higher Th/Yb and negative Ta-Nb-Ti anomaly on the primitive mantle-normalized multi-element spidergrams emphasize the involvement of a subducted component in the lithospheric mantle source. Although, the mineral chemistry and geochemistry is akin to Alaskan-type intrusion, lack of concentric zoning of lithologies (olivine-rich ultramafic rocks in centre surrounded by mafic rocks), rarity of primary hornblende and abundance of orthopyroxene contradict it to be an Alaskan-type intrusion. It is suggested that the mantle source region of the Pulivendla ultramafic-mafic rocks was modified by a fluid-induced metasomatism during an ancient subduction event. Further, Al-in-olivine thermometry suggests crystallization temperature between 1410°and 1484°C, which is 260°C higher than the average temperature of MORB. Similarly, the estimated mantle potential temperature is also significantly higher ([1600°C) than the different secular cooling models of the earth at *1.88-1.89 Ga and consistent with the thermal regime of a mantle plume. The existence of mantle plume during 1.88-1.90 Ga, which has played an important role in the genesis of mafic-ultramafic sills of the Cuddapah basin, is also well supported by a radiating mafic dyke swarm, domal uplift and magmatic underplating.

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Mantle Potential Temperature Estimates and Primary Melt Compositions of the Low-Ti Emeishan Flood Basalt

Cited by 27 publications

References 104 publications

In Situ Geochemical Compositions of the Minerals in Basaltic Rocks from the West Philippine Basin: Constraints on Source Lithology and Magmatic Processes

In Situ Geochemical Compositions of the Minerals in Basaltic Rocks from the West Philippine Basin: Constraints on Source Lithology and Magmatic Processes

In Situ LA-ICP-MS Analysis of Minerals Hosted by Late Cenozoic Basaltic Rocks from Thailand

Paleoproterozoic ($$\sim$$1.88–1.89 Ga) ultramafic–mafic sills, Cuddapah basin, India—revisited: Implications for interaction between mantle plume and metasomatized subcontinental lithospheric mantle

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