Early earth geodynamics: cross examining the geological testimony

Kemp, Anthony I.S.

doi:10.1098/rsta.2018.0169

Cited by 15 publications

(4 citation statements)

References 88 publications

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“…Such a regime over this timeframe is based on evidence from numerical modeling, geochemical data for either reworking or recycling of lithosphere, and restricted paleomagnetic data, the latter limited to the Juvenile Earth phase. If lateral motion in a squishy‐lid regime is valid, it must also be able to account for the spatially focused greenstone and TTG magmatic records of cratons that temporally extends over 100s of millions of years (Figure 11; e.g., Hickman, 2012; Kemp, 2018). The geochemical and isotopic signature of this magmatism indicates ongoing mantle input as well as crustal melting and reworking (e.g., Figure 13; Mulder et al., 2021).…”

Section: Future Directions (A Way Forward)mentioning

confidence: 99%

Secular Evolution of Continents and the Earth System

Cawood

Chowdhury

Mulder

et al. 2022

Reviews of Geophysics

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Our planet is unique in the solar system in having a bimodal distribution of crustal types (continental and oceanic), the presence of liquid water at its surface, an oxygenated atmosphere, and a prolific and diverse biosphere. The evolving yet linked nature of these elements, across the range of spatial and temporal scales that operate on the planet, indicates complex and dynamic cycling between the solid (lithosphere, mantle, and core) and surficial (oceans, atmosphere, and biosphere) reservoirs. This linked evolution occurs in response to heat dissipation from the planet's interior, modulated by input of solar energy to the surficial reservoirs. During its very early history the Earth lacked these crustal and surficial features and, after initial accretion from the solar nebula, likely consisted of a magma ocean (e.g., Elkins-Tanton, 2012). Cooling, density settling, and crystallization resulted in rapid differentiation of the Earth, perhaps over a few tens of millions of years, and included formation of core, mantle, proto-crust, and atmosphere (Figure 1; Elkins-Tanton, 2008. Establishing the cascading succession of

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Section: Future Directions (A Way Forward)mentioning

confidence: 99%

Secular Evolution of Continents and the Earth System

Cawood

Chowdhury

Mulder

et al. 2022

Reviews of Geophysics

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“…3.50 Ga, the mafic and intermediate/felsic crustal reservoirs remained isotopically isolated from each other and from the mantle for at least 200 Ma. One possible implication is that mobile lid tectonics was not a global process during the Eo/Palaeoarchaean and that vertical tectonics remained predominant in the Pilbara area [87]. The tectonic settings of crustal evolution started to change only after 3.2 Ga, when signs of lateral movements that lead to the ceasing of the diapiric doming start to appear in the EPT [36,88].…”

Section: Palaeoarchaean Crustal Evolution In Pilbaramentioning

confidence: 99%

Evidence for Protracted Intracrustal Reworking of Palaeoarchaean Crust in the Pilbara Craton (Mount Edgar Dome, Western Australia)

et al. 2022

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~3.5-2.8 Ga granitoids from the Pilbara Craton in Western Australia are one of the most ancient and best-preserved records of early processes of continental crust generation. A number of recent studies have focused on the nature of the mantle source from which Pilbara granitoids derived, yet no consensus has been reached on whether the mantle was chondritic or depleted in the Eo/Palaeoarchaean. Here we present integrated whole-rock (major and trace elements) and zircon (U-Pb and Lu-Hf isotopes) data for 10 granitoids sampled across the Mount Edgar Dome, which recorded four main magmatic events between 3.47 and 3.23 Ga. Whole-rock major and trace element analyses suggest that the samples belong to two distinct petrogenetic groups. The first group is akin to the tonalite-trondhjemite-granodiorite (TTG) suite, representing highly fractionated magmas initially formed by partial melting of a basaltic crust. The second group, here classified as granites, is best interpreted by the remelting of a basaltic crust and the addition of more evolved material, and it is striking that TTG-like and granitic magmas occurred coevally in time and space. Overall, both groups were formed through intense intracrustal differentiation processes that lead to the loss of significant geochemical information about their original sources. High-precision Lu-Hf analyses in zircon allow to obtain such information and to trace back the isotopic composition of the Palaeoarchaean mantle. A clear change from superchondritic to subchondritic Hf isotope compositions is observed between 3.47 and 3.23 Ga. The superchondritic Hf isotope composition of the 3.47 Ga old granitoids substantiates derivation from a depleted mantle source that separated from the chondritic mantle prior to 3.8 Ga. The presence of ca. 3.5 Ga old inherited zircons in younger magmas suggests that crustal remelting processes were involved in their generation. We propose that all granitoids investigated in this study had their crustal sources originated from a single mantle–crust differentiation event that occurred at 3.50 Ga. This event resulted in the differentiation, from the same original mantle, of two distinct crustal reservoirs, i.e., a mafic reservoir with a 176Lu/177Hf ratio of 0.023, and a reservoir of intermediate/felsic composition ( 176Lu/ 177Hf=0.013). 3.32-3.31 Ga-old granitoids were produced by remelting of the mafic reservoir, whereas 3.43 and 3.23 Ga granitoids derived from the intermediate/felsic reservoir. Overall, our data suggest that protracted intracrustal remelting processes and differentiation have played a key role in the formation, evolution, and maturation of the building blocks of continents during the Palaeoarchaean.

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“…Mobilitas ion juga dapat dihitung dengan menggunakan pengukurn yang sebenarnya antara jarak (206)(207)(208)(209)(210)(211)(212)(213)(214)(215) yang ditempuh setiap ion dengan waktu yang diperlukannya untuk menempuh jarak. =…”

Section: Konduktivitasunclassified

Studi Termodinamika Transpor Ionik Natrium Klorida Dalam Air dan Campuran Tertentu

Hidayati¹,

Zainul²

2019

Preprint

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Abstrak. Natrium klorida dikenal dengan garam dapur. Senyawa ini memiliki rumus NaCl dan larut dalam air. Natrium klorida merupakan senyawa yang berwujud padat bentuk kristal dan berwarna putih. Natrium klorida merupakan senyawa ionik karena adanya ikatan antara logam natrium dengan non logam klorin. Natrium klorida, didalam air dapat terion menjadi ion ion penyusunnya. Penulisan review ini bertujuan untuk menganalisis interaksi molekul pada NaCl yang dilarutkan dalam air. Metode yang digunakan dalam menganalisis interaksi molekul adalah dengan permodelan menggunakan aplikasi ChemDraw 3D. Sedangkan untuk parameter mobilitas ion, konduktivitas, viskositas, dan konduktivitas molar digunakan perhitungan dan data dari salah satu jurnal yang telah di review. Penggunaan ChemDraw 3D dan ChemDraw 2D sebagai langkah untuk menganalisis atom atom penyusun NaCl beserta molekul dan pergerakan molekulnya. Hasil yang didapatkan yaitu struktur natrium klorida dengan analisis molekular 2D dan 3D. Analisis jari-jari natrium klorida pada Chemdraw 3D didapatkan sebesar 2,530A, dan jari jari atom natrium dan klor masing-masingnya sebesar 1.287A dan 1.688A. Setelah dilakukan optimasi MMFF94, didapatkan energi sterik sebesar 0.00073874 kcal/mol dan energi molekul bergerak dalam 30 interaksi atomnya adalah 101,4 kcal/mol. Natrium klorida mempunyai beberapa sifat termokimia dalam fasa padat pada tekanan 1 atm dan suhu 25°C ΔGf° -411.2, kj/mol, ΔHf° -384.1S° 72.1 dan C 50.5. Mobilitas ion natrium sebesar 5,19 m 2 s -1 V -1 dan mobilitas ion klorin bernilai 7,91 m 2 s -1 V -1 .

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Early earth geodynamics: cross examining the geological testimony

Abstract: One contribution of 14 to a discussion meeting issue 'Earth dynamics and the development of plate tectonics'.

Cited by 15 publications

References 88 publications

Secular Evolution of Continents and the Earth System

Secular Evolution of Continents and the Earth System

Evidence for Protracted Intracrustal Reworking of Palaeoarchaean Crust in the Pilbara Craton (Mount Edgar Dome, Western Australia)

Studi Termodinamika Transpor Ionik Natrium Klorida Dalam Air dan Campuran Tertentu

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