scholarly journals Paleogene granite magmatism in the north of the Truong Son belt and implication for crustal evolution

2021 ◽  
Author(s):  
Huan Trinh Dinh ◽  
Tri Luu Cong ◽  
Anh Nguyen Tuan ◽  
Anh Tran Viet ◽  
Giang Phan Hoang ◽  
...  
Keyword(s):  
Geochemical Characteristics ◽  
Isotopic Ratios ◽  
Crustal Evolution ◽  
The North ◽  
Metamorphic Zone ◽  
Crustal Origin ◽  
Granite Magmatism

Abundant granitoids aged 24.59 Ma to 28.62 Ma were exposed along Phu Hoat high metamorphic zone, northern of the Truong Son belt, termed Na Khoun complex in Northern Laos (NL) and Ban Chieng complex in Western Vietnam (WV). Ten granitic samples were collected from these complexes show geochemical characteristics of high SiO2 and K2O contents, medium peraluminous that belong to S-type granites. Initial 87Sr/86Sr isotopic ratios and εNd(t) are broad values of 0.708507 to 0.74539 and -5.22 to -12.66, respectively, together with high 206Pb/204Pb (18.864-19.392), 207Pb/204Pb (15.736-15.841) and 208Pb/204Pb (39.224-40.080) which indicated crustal origin, we suggest that the NL-WV intrusion was associated with transpression form by the India-Asia collision events during Cenozoic.

Multistage late Neoarchaean crustal evolution of the North China Craton, eastern Hebei

2011 ◽  
Vol 189 (1-2) ◽  
pp. 43-65 ◽  
Author(s):  
Allen P. Nutman ◽  
Yusheng Wan ◽  
Lilin Du ◽  
Clark R.L. Friend ◽  
Chunyan Dong ◽  
...  
Keyword(s):  
North China Craton ◽  
North China ◽  
Crustal Evolution ◽  
The North

Continental crustal evolution and synchronous metallogeny through time in the North China Craton

2020 ◽  
Vol 194 ◽  
pp. 104169 ◽  
Author(s):  
Mingguo Zhai ◽  
Xiyan Zhu ◽  
Yanyan Zhou ◽  
Lei Zhao ◽  
Ligang Zhou
Keyword(s):  
North China Craton ◽  
North China ◽  
Crustal Evolution ◽  
The North

scholarly journals Geochemical and Sr–Nd isotopic constraints on the petrogenesis and geodynamic significance of the Jebilet magmatism (Variscan Belt, Morocco)

2013 ◽  
Vol 151 (4) ◽  
pp. 666-691 ◽  
Author(s):  
ABDERRAHIM ESSAIFI ◽  
SCOTT SAMSON ◽  
KATHRYN GOODENOUGH
Keyword(s):  
Partial Melting ◽  
Wall Rock ◽  
Ultramafic Rocks ◽  
Isotopic Ratios ◽  
Isotopic Signatures ◽  
Plate Convergence ◽  
Metasedimentary Rocks ◽  
Microgranular Enclaves ◽  
Crustal Origin ◽  
Shallow Crust

AbstractIn the Variscan fold belt of Morocco, the Jebilet massif is characterized by Palaeozoic metasedimentary rocks intruded by syntectonic magmatism that includes an ultramafic–granitoid bimodal association and peraluminous granodiorites emplacedc. 330 Ma, intruded by younger leucogranitesc. 300 Ma. The mafic–ultramafic rocks belong to a tholeiitic series, and display chemical and isotopic signatures consistent with mixing between mantle-derived and crust-derived magmas or assimilation and fractional crystallization. The granites within the bimodal association are mainly metaluminous to weakly peraluminous microgranites that show characteristics of A2-type granites. The peraluminous, calc-alkaline series consists mainly of cordierite-bearing granodiorites enclosing magmatic microgranular enclaves and pelitic xenoliths. Detailed element and isotope data suggest that the alkaline and the peraluminous granitoids were formed in the shallow crust (<30 km) by partial melting of tonalitic sources at high temperatures (up to 900°C) and by partial melting of metasedimentary protoliths at relatively low temperatures (c. 750°C), respectively. Mixing between the coeval mantle-derived and crust-derived magmas contributed to the large variation of initial εNdvalues and initial Sr isotopic ratios observed in the granitoids. Further contamination occurred by wall-rock assimilation during ascent of the granodioritic plutons to the upper crust. The ultramafic–granitoid association has been intruded by leucogranites that have high initial Sr isotopic ratios and low initial εNdvalues, indicating a purely crustal origin. The heating events that caused emplacement of the Jebilet magmatism are related to cessation of continental subduction and convective erosion/thinning of the lithospheric mantle during plate convergence.

Caledonian magmatism record within Hebridean Terrane? Loch Roag dyke (Lewis Island, northern Scotland) non-peridotitic xenoliths and megacrysts as messengers from deep lithosphere.

2020 ◽  
Author(s):  
Daniel Buczko ◽  
Magdalena Matusiak-Małek ◽  
Brian J. G. Upton ◽  
Theodoros Ntaflos ◽  
Sonja Aulbach ◽  
...  
Keyword(s):  
North Atlantic ◽  
Parental Magma ◽  
Geological Structure ◽  
Trace Element Composition ◽  
Isotopic Ratios ◽  
The North ◽  
Source Regions ◽  
Mantle Sources ◽  
History Of ◽  
North Atlantic Craton

&lt;p&gt;The northernmost part of Scotland &amp;#8211; the Hebridean Terrane &amp;#8211; is formed of Archean rocks originally being part of the Laurentian North Atlantic Craton. The geological history of the terrane is well recognised, however details of its internal structure remain unknown. The Eocene (Faithfull et al. 2012, JGS) Loch Roag monchiquite (Lewis Island) sampled deep-seated lithologies, providing insight on evolution and geological structure of the deeper lithosphere of the Hebridean terrane. The monchiquite comprises abundant xenoliths of ultramafic, mafic and felsic rocks. The peridotitic xenoliths represent pieces of Archean mantle underlying marginal parts of the North Atlantic Craton, whereas the origin of non-peridotitic lithologies is uncertain.&lt;/p&gt;&lt;p&gt;The studied suite of samples comprises two groups: 1) &amp;#8220;xenoliths&amp;#8221; of diorites (plagioclase, clinopyroxene, orthopyroxene, apatite, opaques) and biotite clinopyroxenites (+apatite), 2) &amp;#8220;megacrysts&amp;#8221; of clinopyroxene and K-feldspar, both with inclusions of clinopyroxene, biotite and apatite. Megacrysts of alkali-rich feldspar associated with corundum and HFSE-bearing minerals, and composite xenoliths formed of pyroxenite and K-feldspar-rich lithology have also been described from this locality (Menzies et al., 1986, Geol. Soc. Australia Spec. Pub.; Upton et al., 2009, Mineral. Mag.).&lt;/p&gt;&lt;p&gt;We interpret the &amp;#8220;xenoliths&amp;#8221; as products of crystallization of fractionated mafic melt(s). The primary character of Sr isotopic ratios in plagioclase (&lt;sup&gt;87&lt;/sup&gt;Sr/&lt;sup&gt;86&lt;/sup&gt;Sr &lt;0.702) suggests that parental melt of those lithologies originated from melting of depleted lithospheric mantle sources. The &amp;#8220;megacrysts&amp;#8221; represent fragments of disintegrated alkaline pegmatite(s) formed from melt of plausible mantle origin, possibly enriched (&lt;sup&gt;87&lt;/sup&gt;Sr/&lt;sup&gt;86&lt;/sup&gt;Sr in feldspar &gt;0.704).&lt;/p&gt;&lt;p&gt;Trace element composition, similar Sr isotopic ratios of minerals and textural features of &amp;#8220;xenoliths&amp;#8221; and &amp;#8220;megacrysts&amp;#8221; groups suggest their close genetic relationship. This geochemical resemblance may reflect crystallisation from primarily similar melt(s) and source regions affected by similar metasomatism. Petrographic features observed in rocks described by Upton et al., (2009) imply that the parental magma of megacrysts might have intruded the rocks forming the xenoliths group. Moreover, the Rb-Sr ages of xenoliths (Der-Chuen et al., 1993, GCA) indicate crystallisation during (or shortly after) Caledonian orogeny. Preliminary age relationship between groups will be determined by on-going Rb-Sr dating of megacrysts.&lt;/p&gt;&lt;p&gt;Xenoliths similar to diorites from Loch Roag were reported by Badenszki et al. (2019, JoP) from the Midland Valley terrane (&amp;#8220;metadiorites&amp;#8221; of protolith ages ca. 415 Ma). They were interpreted as products of alkaline syn-/post-collisional Caledonian magmatism. Our study shows that non-peridotitic xenoliths from Loch Roag dyke might represent a record of similar (or the same) magmatism in the northernmost, &amp;#8220;Laurentian&amp;#8221; part of Scotland. This study presents the first report of such Caledonian magmatism record within the Hebridean Terrane.&lt;/p&gt;&lt;p&gt;Founded by Polish National Science Centre grant no. UMO-2016/23/B/ST10/01905, part of the data was obtained thanks to the Polish-Austrian project no. WTZ PL 08/2018.&lt;/p&gt;

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