Elemental and Sr-Nd-Hf isotopic constraints on the origin of Late Jurassic adakitic granodiorite in central Fujian province, southeast China

Abstract

This paper presents the first detailed SHRIMP or LA-ICP-MS zircon U-Pb dating, major and trace element geochemical and Sr-Nd-Hf isotopic data of an adakitic pluton (Tangquan pluton) and an I-type granitic pluton (Xiadao pluton) in central Fujian. SHRIMP and LA-ICP-MS zircon U-Pb dating indicates that the Tangquan and Xiadao plutons were emplaced in the Late Jurassic (~160 Ma) and Early Cretaceous (~143 Ma), respectively. The Tangquan pluton is mainly composed of high-K calc-alkaline granodiorite. The rocks show adakitic affinities, characterized by high Sr and low Y and Yb contents, with high Sr/Y ratios, and by high Mg#. They have initial 87 Sr/ 86 Sr of 0.7084-0.7087, ε Nd (T) of −8.8 to −9.0 and ε Hf (T) (in-situ zircon) of −11.2. Detailed elemental and isotopic data suggest that the Tangquan adakitic granodiorite was formed by partial melting of Paleoproterozoic metamorphic basement at a depth of~40 km (P~12.5 kbar) plus additional input from coeval basaltic magma. The Xiadao pluton consists of monzogranite, syenogranite and alkali-feldspar granite. These granites are high-K calc-alkaline and belong to I-type. They have relatively low Sr and high Y and Yb contents and show similar Mg# to pure crustal melts. The Xiadao granites have slightly higher initial 87 Sr/ 86 Sr (0.7095-0.7102) and lower ε Nd (T) (−9.0 to −9.4) and ε Hf (T) (−14.4; in-situ zircon) than the Tangquan granitoids. Detailed elemental and isotopic data suggest that the Xiadao I-type granites were formed by partial melting of Paleoproterozoic metamorphic basement at a depth of~30 km (P~10 kbar).

Geochronology, Geochemistry, and Geodynamic Relationship of the Mafic Dykes and Granites in the Qianlishan Complex, South China

“…Although the granite porphyry exhibits high La/Yb and Dy/Yb, the Yb content of granite porphyry (3.9-8.5 ppm) do not exhibit significant differences in the main phase granite (6.12-13.1 ppm). Therefore, we prefer that the high La/Yb and Dy/Yb of granite porphyry mainly inherit from the source [80]. Thus, we conclude that the source of the mantle-derived components of the granite porphyry is the Qianlishan mafic dykes, which display similar Zr/Nb and Zr/Hf ratios to the granite porphyry (Figure 12) and conform to the chronology results above.…”

“…Therefore, the main-phase granites may be the products of parental melting of ancient basement with highly negative εHf(t) values mixed with mantle-derived components with εHf(t) values around zero. However, compared to the Qianlishan mafic dykes, the main-phase granite samples display high HREE (Yb = 6.12-13.1 ppm) and Y (34.2-102 ppm) contents and flat HREE patterns, precluding a residual phase within the crustal source [80]. Moreover, these samples have significant negative anomalies of Eu and Sr, enrichment in LILE, and the trace element patterns requiring partial melting of source rocks within the stability field of plagioclase [73].…”

Climate‐Dependent Sediment Composition and Transport of Mountainous Rivers in Tectonically Stable, Subtropical East Asia

“…Mixing curves are divided into 10% increments. Data of the parent‐rocks are from Zhao et al (), Chen and Jahn (), Yu et al (), Wang et al (, , ), and Li et al (). (c) Comparison of Nd isotope ratios of the catchment parent‐rocks and the analyzed riverbed sediments.…”

“…The downstream basin is dominated by Jurassic‐Cretaceous igneous rocks and volcano‐sedimentary strata (Figure ; Chen & Jahn, ; Li et al, ). The Precambrian and Paleozoic rocks have higher 87 Sr/ 86 Sr and lower 143 Nd/ 144 Nd ratios than the Mesozoic rocks (Chen & Jahn, ; Li et al, ; Yu et al, ; Wang et al, , , ; Zhao et al, ). Annual precipitation in the river basin ranges from approximately 1,500 to 2,000 mm and displays high spatiotemporal heterogeneity (Figures c and d).…”

“…Mixing curves are divided into 10% increments. Data of the parent-rocks are from Zhao et al (1995), Chen and Jahn (1998), Yu et al (2012), Wang et al (2013Wang et al ( , 2014Wang et al ( , 2015, and Li et al (2014) (Gaillardet, Dupré & Allègre, 1999 Figures 3a and S2).…”