China
Africa
Explore chapters and articles related to this topic
Repository of stones used in Delhi and Agra UNESCO Sites
Published in Gurmeet Kaur, Sakoon Singh, Anuvinder Ahuja, Noor Dasmesh Singh, Natural Stone and World Heritage, 2020
Gurmeet Kaur, Sakoon Singh, Anuvinder Ahuja, Noor Dasmesh Singh
The BGC comprises Tonalite-Trondhjemite-Granodiorite (TTG), migmatitic gneisses, amphibolites, schists, quartzites, calc-silicate rocks, granulites, granites and pegmatites. The BGC is also referred to as the Mewar Gneiss and the Bhilwara Supergroup (Wiedenbeck et al., 1996; Roy and Kröner, 1996). The BGC is overlain by the Paleoproterozoic Aravalli, Meso-Neoproterozoic Delhi and Vindhyan Supergroups (Rasmussen et al., 2002; Ray et al., 2002; Gregory et al., 2006; Mckenzie et al., 2013 and references cited therein). The Aravalli Supergroup primarily consists of metavolcanics, with low to medium grade metasediments comprising quartzites, phyllites, schists, stromatolitic dolostone, phosphorite and greywacke (Heron, 1953; Roy and Paliwal, 1981; Gupta et al., 1981, 1997; Sinha-Roy et al., 1998; Roy and Kataria, 1999). The Aravalli Supergroup rocks are intruded by mafic and ultramafic rocks, besides the post-Aravalli and post-Delhi granites and pegmatites (Sharma, 1953; Srivastava, 1988). The Delhi Supergroup extends for a distance of ~700 km from Delhi and south Haryana to Idar in north Gujarat, as a narrow, linear belt that governs the NNE-SSW orographic trend of AMB. The Delhi Supergroup is divided into the older North Delhi Fold Belt (NDFB) and a younger South Delhi Fold Belt (SDFB) (Fig. 3.6; Sinha-Roy, 1984; Deb et al., 2001; Saha and Mazumder, 2012; Mckenzie et al., 2013 and references cited therein).
Mafic dykes of the southeastern Gawler Craton: ca 1564 Ma magmatism with an enriched mantle source
Published in Australian Journal of Earth Sciences, 2022
A. J. Reid, C. E. Wade, E. A. Jagodzinski
The Daly Head Metadolerite represents tholeiitic gabbros formed in an intraplate, continental to back arc setting (Figure 12a). Enriched lithospheric trace elements such as high Ba, Pb and La are common in continental flood basalts, which reflect a contribution from the continental lithosphere (Baker et al., 2000). Low to moderate combined Nb/La–La/Yb ratios suggest the source region for Daly Head Metadolerite is a mixed asthenospheric–lithospheric mantle source (Figure 12b). The trend in the data on Figure 12b suggests a mixing array with tonalite–trondhjemite–granodiorite (TTG) or GLOSS in the lithospheric mantle source. The overall SiO2 content of the Daly Head Metadolerite is relatively low, negative anomalies of Nb and Ta are modest and negative Ti anomalies are insignificant, suggesting the degree of crustal assimilation must be proportionally small, and therefore the geochemical enrichment could have been present within the mantle source prior to melt extraction.
Geotourism and geoparks for sustainable rural development and poverty alleviation: Huanggang Dabieshan UNESCO Global Geopark, China
Published in Australian Journal of Earth Sciences, 2022
The predominantly granitic intrusive rocks of the DBGG are Neoarchean TTG rock series (Ar3TTG) and Mesozoic shoshonitic or high-K calc-alkaline intrusive rocks. The TTG rock series, which are made up of epeirogenic granite intrusive rocks composed of trondhjemite, tonalite and granodiorite, crop out in the Luotian dome (Figure 2e) and have been dated at 2664 ± 13 Ma (Ge et al., 2001). The TTG series with spatially and temporally related supracrustal rocks is the dominant constituent of Archean cratons and are regarded as the key archives of Earth’s evolution, in particular the composition of continental crust and processes and mechanisms of crust formation (Eriksson & Condie, 2014; Martin et al., 2005; Shan et al., 2016). The DBGG includes crustal growth and reworking events at ca 2.6 Ga (Ge et al., 2001).
Genetic and ore-forming ages of the Fe–P–(Ti) oxide deposits associated with mafic–ultramafic–carbonatite complexes in the Kuluketage block, NW China
Published in Australian Journal of Earth Sciences, 2019
W. Chen, X. B. Lü, X. F. Cao, Q. Yuan, X. D. Wang
Precambrian magmatic activities were pulsating, and a mass of magmatic rocks are distributed in the Kuluketage block (Cao et al.,2010; Ge et al.,2014a; Ge, Zhu, Wilde, & He, 2014b; Zhang et al., 2012a). Archean rocks are well exposed to the north of the Kuluketage block. The oldest rocks are known as the Tuoge Complex (or ‘Tuogelakbrak Complex’), which yielded a zircon multigrain U–Pb TIMS age of 2582 ± 11 Ma and a Pb–Pb zircon evaporation age of 2488 ± 10 Ma (Lu, 1992). The latest SHRIMP and LA-ICP-MS geochronology studies show that the 2.65–2.53 Ga tonalite–trondhjemite–granodiorite (TTG) rocks and K-rich granites are widely distributed (Hu & Wei, 2006; Long et al., 2011a; Shu, Deng, Zhu, Ma, & Xiao, 2011; Zhang et al., 2012a). Paleoproterozoic metamorphic rocks are also widespread in the Kuluketage block, and they are known as the Xingditage Group. This group is mainly distributed in the western Kuluketage block, and consists of older metamorphic mafic, felsic intrusions and high-grade metamorphic supracrustal rocks. Mesoproterozoic to early Neoproterozoic granitoids and diabasic dykes are widespread in this area (Feng et al., 1995; Lu et al., 2008a, 2008b). Middle Neoproterozoic to Phanerozoic rocks consist of mafic dyke swarms, bimodal intrusions, bimodal volcanic rocks, and granitoids (Cao, Lv, & Gao, 2012; Chen, Cao, Lü, Zhu, & He, 2017b; Ge et al., 2012; Han et al., 2018; Long et al., 2011b; Xu, Kou, Song, Wei, & Wang, 2008; Xu et al., 2009; Xu, Zou, Chen, He, & Wang, 2013a; Zhang et al., 2007a; Zhang, Li, Li, & Ye, 2009a; Zhu et al., 2008). A diverse set of Neoproterozoic magmatic rocks have been documented in the Kuluketage block, including: (1) ca 1000–860 Ma metamorphic rocks; (2) ca 810 Ma mafic–ultramafic–carbonatite complexes; (3) ca 810 Ma and 760–730 Ma bimodal intrusive complexes; (4) ca 830–735 Ma voluminous granitoids; (5) ca 810 Ma, 760–735 Ma and 650–630 Ma mafic dykes; and (6) ca 735 Ma volcanic rocks (Cao et al.,2011; Lv, 2017; Zhang, Zou, Wang, Li, & Ye, 2012b; Zhu et al., 2011a).