Extraction of fractionated interstitial melt from a crystal mush system generating the Late Jurassic high-silica granites from the Qitianling composite pluton, South China: Implications for greisen-type tin mineralization

Two Distinct Fractional Crystallization Mechanisms of A-Type Granites in the Nanling Range, South China: A Case Study of the Jiuyishan Complex Massif and Xianghualing Intrusive Stocks

“…However, this result is unrealistic in nature. In a crystal mush system, the less-evolved granites are inferred to represent a residual crystal mush comprising the cumulate crystals and a proportion of highly fractionated interstitial melts, whereas the high-silica granites represent the extracted, highly fractionated interstitial liquid from a crystal mush [15]. We therefore suggest that the composition of the extracted liquid is the same as that of the most evolved Pangxiemu granite sample, and the composition of the residual crystal mush approximates the average composition of the Shaziling, Xishan and Jinjiling granites.…”

“…According to this model, approximately 60%−80% fractionation is needed to form the Pangxiemu granites (Figure 14a,b). To better constrain the magma fractionation of the Jiuyishan complex massif, Rayleigh fractionation crystallization modeling was carried out and Ba, Sr and Rb were se- To better constrain the magma fractionation of the Jiuyishan complex massif, Rayleigh fractionation crystallization modeling was carried out and Ba, Sr and Rb were se- and a proportion of highly fractionated interstitial melts, whereas the high-silica granites represent the extracted, highly fractionated interstitial liquid from a crystal mush [15]. We therefore suggest that the composition of the extracted liquid is the same as that of the most evolved Pangxiemu granite sample, and the composition of the residual crystal mush approximates the average composition of the Shaziling, Xishan and Jinjiling granites.…”

“…However, such mechanisms are based on mafic magmas, and felsic magmas may not be suitable for these mechanisms [68]. However, some studies also argue that F and other volatiles can remarkably reduce magma viscosity, with clear evidence showing that abundant flow structures were found in field observations of granite systems and that flowage differentiation and gravitational settling can also occur as fractional crystallization mechanisms of felsic magmas [17,18,80] Recently, a crystal mush system has been proposed to explain the existence of granitic rocks with spatially and temporally related, high-silica rhyolites: large silicic magma chambers are widely perceived as upper crustal mush at a high crystallinity, and these magma chambers are commonly placed into two closely spatio-temporally related crystalpoor and crystal-rich units, respectively [15,58]. The crystal mush system can also be used to interpret the formation of complex massifs.…”

“…The most developed occurrence is a complex massif, while the majority of complex massifs are composed of several large-scale A-type granitic batholiths (>100 km 2 ). Within the complex massif, each single pluton can be spatially and temporally related or lithologically and geochemically linked [14][15][16]. The other occurrence is intrusive stock.…”

Geochemical Characteristics, Zircon U-Pb Ages and Lu-Hf Isotopes of Pan-African Pegmatites from the Larsemann Hills, Prydz Bay, East Antarctica and Their Tectonic Implications

“…The results indicate that the five samples are classified as I-and S-type granites (Figure 10a) and fractionated I-, S-, and M-type granites (Figure 10b) [71], aligning with volcanic arc granites (VAG) and syn-collisional granites (syn-COLG) (Figure 11a). They are linearly projected near the boundary between volcanic arc granite (VAG) and syn-collisional granite (syn-COLG) (Figure 11b) [72].…”