Geochemistry of Proterozoic granulites from northern Prince Charles Mountains, East Antarctica

1992 ◽  
Vol 4 (1) ◽  
pp. 59-69 ◽  
Author(s):  
N.C. Munksgaard ◽  
D.E. Thost ◽  
B.J. Hensen

The late Proterozoic basement of the Porthos Range northern Prince Charles Mountains, east Antarctica, is dominated by a suite of felsic to mafic granulites derived from igneous and, less importantly, sedimentary protoliths. Compositionally, they are broadly similar to granulites occurring along the Mac. Robertson Land coast and southern Prince Charles Mountains. Ultramafic to mafic orthopyroxene' + clinopyroxene granulites with relict igneous layering occur as lenses within the felsic to mafic granulites, and show compositional evidence of a cumulate origin. The felsic to mafic granulites are intruded by several large charnockite bodies that have similarities to the Mawson Charnockite, and may have formed via a two-stage partial melting process. The charnockite and host granulites are chemically very similar, and both may have been derived from a common middle to lower crustal source region. Undepleted K/Rb ratios suggest retention of original chemistry, with variations being due to fractionation processes. Normalized trace element patterns resembling modern-day arc settings suggest that the Porthos Range granulites were possibly generated in a subduction zone environment.

The pattern of incompatible elements (K, Rb, Ba, r.e.e., H f etc.) is the same for most samples from the lunar highlands. It is suspected that this pattern of incompatible elements is typical for the whole lunar crust. This seems to be a reasonable assumption as one can show from heat flow data that a large part of the Moon’s total U (and consequently other incompatible elements) has to be concentrated in a thin crustal layer, which certainly contributes to the sampled highland rock types. It is supposed that a partial melting process of the major part of the Moon has extracted the trace elements from the interior into the crust. The patterns of incompatible elements of mare basalts are those expected if a second partial melting process were applied to the trace-element-depleted interior. Some consequences of this model are discussed. A relatively constant Sr and Eu distribution through the whole Moon is inferred, implying a positive Eu-anomaly in the lunar interior.


2020 ◽  
Vol 5 (2) ◽  
pp. 218-220
Author(s):  
Amir Peyman Soleymani ◽  
Masoud Panjepour ◽  
Mahmood Meratian

Cementite extraordinary mechanical properties have drawn the attention of researchers in recent years. But, the limited methods for the production of this material, led to the production of iron with more than 2.1%wt carbon content beside free carbon by simultaneous thermal-mechanical activation of hematite and graphite mixture at 800°C for 6 hours in the present research. Then, a structure with more than 80%wt cementite was obtained through partial melting process at 1180°C for 25 minutes.


2019 ◽  
Vol 56 (12) ◽  
pp. 1409-1436 ◽  
Author(s):  
Xue-Ming Yang ◽  
Derek Drayson ◽  
Ali Polat

Detailed field observations indicate that Neoarchean S-type granites were emplaced along and (or) proximal to some terrane (tectonic) boundary zones in the western Superior Province, southeastern Manitoba. These S-type granites are characterized by the presence of at least one diagnostic indicator mineral, such as sillimanite, cordierite, muscovite, garnet, and tourmaline. They are medium- to high-K calc-alkaline, moderately to strongly peraluminous (ANKC >1.1), and contain >1% CIPW normative corundum. Compared with more voluminous, older I-type granitoids in tonalite–trondhjemite–granodiorite suites in the region, the S-type granites occur as relatively small intrusions and have high (SiO2 >72 wt.%) contents with a small silica range (SiO2 = 72.2–81.2 wt.%), but a large range of Zr/Hf (17.1–43.8) and Nb/Ta (0.3–16.0) ratios. These geochemical characteristics suggest that the S-type granites were derived from partial melting of heterogeneous sedimentary rocks deposited as synorogenic flysch that underwent burial and crustal thickening during terrane collision. Although the S-type granites display geochemical variations in individual and between different plutons, their low Sr (<400 ppm) and Yb (<2 ppm) contents and low Sr/Y (<40) and La/Yb (<20) ratios are consistent with a partial melting process that left a granulite-facies residue consisting of plagioclase, pyroxene, and ± garnet. The S-type granites display low zircon saturation temperatures (mostly <800 °C) and low emplacement pressures (<300 MPa), similar to strongly peraluminous leucogranites formed in the Himalayas. Therefore, we propose that the Neoarchean S-type granites in the western Superior Province, whose source rocks were deposited between colliding tectonic blocks between 2720 and 2680 Ma, may serve as a geological marker of some Archean terrane boundary zones.


1991 ◽  
Vol 27 (2) ◽  
pp. 1254-1257 ◽  
Author(s):  
J. Kase ◽  
T. Morimoto ◽  
K. Togano ◽  
H. Kumakura ◽  
D.R. Dietderich ◽  
...  

Author(s):  
Takashi S. Kodama ◽  
Yoshiyuki Tanaka ◽  
Miyo Morita ◽  
Takashi Yura ◽  
Yoshimasa Kyogoku ◽  
...  

2015 ◽  
Vol 44 (3) ◽  
pp. 563-566
Author(s):  
Zhang Shengnan ◽  
Li Chengshan ◽  
Hao Qingbin ◽  
Lu Tianni

Geosciences ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 319 ◽  
Author(s):  
Tomas Næraa ◽  
Thomas F. Kokfelt ◽  
Anders Scherstén ◽  
Andreas Petersson

Ferroan granitoid intrusions are rare in the Archaean rock record, but have played a large role in the evolution of the Proterozoic crust, particular in relation to anorthosite-mangerite-charnockite-granite suites. Here we discuss the petrogenesis of the ca. 2785–2805 Ma ferroan Ilivertalik Intrusive Complex, which has many geochemical similarities to Proterozoic iron rich granitoids. We present major and trace element whole rock chemistry and combined in-situ zircon U-Pb, Hf and O isotope data. The intrusive complex divides into: (i) minor tabular units of mainly diorite-tonalite compositions, which are typically situated along contacts to the host basement and (ii) interior larger, bodies of mainly granite-granodiorite composition. Geochemically these two unites display continuous to semi-continuous trends in Haker-diagrams. Whole rock REE enrichment display increases from Yb to La, from 10–25 to 80–100 times chondrite, respectively. The diorite-tonalite samples are generally more enriched in REE compared to the granite-granodiorite samples. The complex has hafnium isotope compositions from around +1.5 to −2.5 epsilon units and δ18O compositions in the range of 6.3 to 6.6‰. The complex is interpreted to be derived from partial melting in a crustal source region during anomalously high crustal temperatures.


2012 ◽  
Vol 513 ◽  
pp. 610-614 ◽  
Author(s):  
W.T. Wang ◽  
Y. Zhao ◽  
M.H. Pu ◽  
X.F. Yang ◽  
H. Zhang ◽  
...  

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