In situ elemental and Sr-O isotopic studies on apatite from the Xu-Huai intrusion at the southern margin of the North China Craton: Implications for petrogenesis and metallogeny

2019 ◽  
Vol 510 ◽  
pp. 200-214 ◽  
Author(s):  
Sai-Jun Sun ◽  
Xiao-Yong Yang ◽  
Guang-Jie Wang ◽  
Wei-Dong Sun ◽  
Hong Zhang ◽  
...  
Keyword(s):  
North China Craton ◽  
North China ◽  
The North ◽  
Southern Margin ◽  
Isotopic Studies

Late Ordovician fore-arc ophiolitic mélange in the southern margin of the Bainaimiao arc: constraints from zircon U–Pb–Hf isotopes and geochemical analyses

2021 ◽  
pp. 1-21
Author(s):  
Yun-Xi Meng ◽  
Zhi-Cheng Zhang ◽  
Jian-Zhou Tang ◽  
Huai-Hui Zhang ◽  
Qi Wang ◽  
...  
Keyword(s):  
North China Craton ◽  
North China ◽  
Tectonic Setting ◽  
Late Ordovician ◽  
Geochemical Characteristics ◽  
Ultramafic Rocks ◽  
The North ◽  
Ophiolitic Mélange ◽  
Southern Margin

Abstract The Harihada–Chegendalai ophiolitic mélange, which is located between the Bainaimiao arc and the North China Craton, holds significant clues regarding the tectonic setting of the southern margin of the Central Asian Orogenic Belt. The ophiolitic mélange is mainly composed of gabbroic and serpentinized ultramafic rocks. Here, zircon U–Pb dating, in situ zircon Hf isotopic, whole-rock geochemical and in situ mineral chemical data from the ophiolitic mélange are reported. The zircons in the gabbroic rocks yielded concordia U–Pb ages of 450–448 Ma and exhibited slightly positive ϵHf(t) values (0.87–4.34). The geochemical characteristics of the gabbroic rocks indicate that they were generated from a mantle wedge metasomatized by subduction-derived melts from sediments with continental crust contamination, in a fore-arc tectonic setting. These rocks also experienced the accumulation of plagioclase. The geochemical characteristics of the ultramafic rocks and their Cr-spinels indicate that they may constitute part of residual mantle that has experienced a high degree of partial melting and has interacted with fluids/melts released from the subducted slab in the same fore-arc tectonic setting. The ophiolitic mélange may therefore have formed in this fore-arc tectonic setting, resulting from the northward subduction of the South Bainaimiao Ocean beneath the Bainaimiao arc during Late Ordovician time, prior to the collision between the Bainaimiao arc and the North China Craton during the Silurian to Carboniferous periods.

PRECISE AGES FOR LODE GOLD MINERALIZATION IN THE XIAOQINLING GOLD FIELD, SOUTHERN MARGIN OF THE NORTH CHINA CRATON: NEW CONSTRAINTS FROM IN SITU U-Pb DATING OF HYDROTHERMAL MONAZITE AND RUTILE

2020 ◽  
Author(s):  
Junchen Liu ◽  
Yitian Wang ◽  
Jingwen Mao ◽  
Wei Jian ◽  
Shikang Huang ◽  
...  
Keyword(s):  
North China Craton ◽  
North China ◽  
Gold Mineralization ◽  
Late Mesozoic ◽  
The North ◽  
Southern Margin ◽  
Lithospheric Extension ◽  
Gold Producer ◽  
Gold Bearing

Abstract The Xiaoqinling gold field, located along the southern margin of the North China craton, is the second largest gold producer in China, which comprises more than 1,200 auriferous quartz veins with a proven gold reserve of at least 800 tons. Previously, the absolute age of the gold metallogenesis in this area has not been well defined due to the lack of suitable dating minerals. This study presents new in situ laser ablation-inductively coupled plasma-mass spectrometry U-Pb ages of coexisting hydrothermal monazite and rutile for the Fancha gold deposit in this area, which yielded 206Pb/238U ages of 127.5 ± 0.7 Ma (n = 65, mean square of weighted deviates [MSWD] = 1.8) and 129.7 ± 4.3 Ma (n = 37, MSWD = 1.4), respectively. Both ages overlap within analytical uncertainty at the 2σ level of significance, suggesting that both gold-bearing veins were emplaced at ca. 128 Ma. Mineralogical observations indicate that the monazite and rutile precipitated simultaneously with gold from the hydrothermal fluid. Our new data, combined with recently published monazite age, define a more precise gold episode, demonstrating that the gold endowment of the Xiaoqinling area was formed during a relatively brief period at ca. 130 to 127 Ma. We suggest that auriferous fluids were generated as a result of interactions between the enriched mantle and the lower crust, which was driven by westward flat slab subduction of the Paleo-Pacific plate during the late Mesozoic. The peak of lithospheric thinning during the postsubduction may have led to the rapid release of gold from the fertilized mantle. Consequently, the large number of gold-bearing veins in the Xiaoqinling area may ultimately be related to the tectonic evolution and mantle fluid processes that occurred during Early Cretaceous lithospheric extension.

Refertilization of lithospheric mantle beneath the North China Craton in Mesozoic: Evidence from in situ Sr isotopes of Fuxin peridotite

Lithos ◽  
2020 ◽  
Vol 364-365 ◽  
pp. 105478 ◽  
Author(s):  
Dongya Zou ◽  
Hongfu Zhang ◽  
Xiaoqi Zhang ◽  
Huiting Zhang ◽  
Benxun Su
Keyword(s):  
North China Craton ◽  
Lithospheric Mantle ◽  
North China ◽  
Sr Isotopes ◽  
The North

scholarly journals Geochemistry and tectonic significance of late Paleoproterozoic A-type granites along the southern margin of the North China Craton

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Yan Wang ◽  
Yi-Zeng Yang ◽  
Wolfgang Siebel ◽  
He Zhang ◽  
Yuan-Shuo Zhang ◽  
...  
Keyword(s):  
North China Craton ◽  
North China ◽  
Published Data ◽  
Pb Isotope ◽  
Granite Sample ◽  
The North ◽  
Southern Margin ◽  
Basement Rocks ◽  
Type Granite ◽  
Melting Product

AbstractThe Longwangzhuang pluton is a typical example of Paleoproterozoic A-type granite intrusions at the southern margin of the North China Craton. This pluton is composed of arfvedsonite granite and minor aegirine–augite granites. Samples from both granite types display similar zircon U-Pb ages with 207U-206Pb ages of 1612 ± 19 Ma [mean square weighted deviation (MSWD) = 0.66] and 1609 ± 24 Ma (MSWD = 0.5), respectively. The granites exhibit similar high silica (SiO2 = 71.1–73.4 wt.%), high alkaline (Na2O + K2O = 8.10–9.26 wt.%, K2O/Na2O > 1), and low Al2O3 (11.8–12.8 wt. %) contents and metaluminous to weakly peraluminous bulk chemistry. The chemical variations of the Longwangzhuang pluton suggest the effects of mineral fractionation. In addition, all samples show typical characteristics of A-type granites, such as high 10000Ga/Al ratios (4.10–7.28), high FeOtot/(FeOtot + MgO) ratios (0.88–0.99), and high Zr (484–1082 ppm), Ce (201–560 ppm), and Y (78–156 ppm) contents. The εNd(t) values and the (206Pb/204Pb)t, (207Pb/204Pb)t, and (208Pb/204Pb)t ratios of the arfvedsonite granite samples vary from −4.6 to –5.3, 15.021 to 17.349, 15.241 to 15.472, and 33.206 to 36.905, respectively, and those for the aegirine–augite granite sample amount at −0.2, 14.421, 15.175, and 33.706. The distinct and variable Nd and Pb isotope values indicate the presence of heterogeneous protoliths. Based on its geochemistry, its low initial Pb isotope ratios, and its enrichment in Nd isotopes, we infer that the Longwangzhuang A-type granite is the partial melting product of basement rocks such as the Taihua Group gneisses accompanied by some involvement of juvenile material from the mantle. Together with published data from other Paleoproterozoic A-type granite plutons exposed at the southern margin of the craton, our findings suggest that these granites had a similar origin. Furthermore, geochemically, they can be divided into two groups: A2-type, which formed earlier (~1.8–1.6 Ga), and A1-type, which formed later (~1.6–1.5 Ga). Combining this information with the variations in whole-rock Nd and zircon Hf isotopic composition at ca. 1.6 Ga, we propose that tectonic transformation from post-orogenic to anorogenic magmatism occurred at the southern margin of the North China Craton at that time.

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