scholarly journals Petrogenesis and tectonic significance of the Mengjiaping beschtauite in the southern Taihang mountains

2021 ◽  
Vol 13 (1) ◽  
pp. 1711-1731
Author(s):  
Haofei Tian ◽  
Ganyu Li ◽  
Jinyong Choi ◽  
Wenlou Luan ◽  
Xingtao Cui ◽  
...  

Abstract The evolution process of the North China Craton has been discussed by many scholars; however, the frame for the timing of the Trans-North China Block has not been fully agreed upon. Related research has mostly focused on the northern and southern sections of the Trans-North China Block, and in-depth studies on intrusive rocks in the central region are lacking. In this study, we conduct a systematic study of the petrography, the whole-rock geochemistry, and the zircon U–Pb dating for the beschtauite intrusion, located in the Mengjiaping area of the Southern Taihang Mountains. Our results demonstrate that the dyke intrusion is mainly composed of beschtauite. Laser ablation inductively coupled plasma mass spectrometry zircon U–Pb dating shows that the beschtauite intrusion occurred at ∼1,880 ± 69 Ma. The beschtauite belongs to I-type granite, Arc tholeiite series, and Cale-alkaline series, with low total alkali, low potassium, and high aluminum. They are also enriched in large-ion lithophile elements, relatively depleted in high-field strength elements, and low total rare-earth elements. Based on the abovementioned data, it is suggested that the magmas for the beschtauite intrusion were metasomatized by oceanic slab subduction in the Late Paleoproterozoic. The formation time of the North China Craton basement should be set to after 1,880 Ma.

2018 ◽  
Vol 10 (1) ◽  
pp. 34-44 ◽  
Author(s):  
Xianghong Meng ◽  
Yu Zhang ◽  
Duoyun Wang ◽  
Xue Zhang

AbstractLaser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) U-Pb dating has been performed on detrital zircons from the Chunshuyao Formation sandstone of Yichuan Basin. The ages of 85 detrital zircon grains are divided into three groups: 252-290 Ma, 1740-2000 Ma, and 2400-2600 Ma. The lack of Early Paleozoic and Neoproterozoic U-Pb ages indicates that there is no input from the Qinling Orogen, because the Qinling Orogen is characterized by Paleozoic and Neoproterozoic material. In combination with previous research, we suggest that the source of the Chunshuyao Formation is most likely recycled from previous sedimentary rocks from the North China Craton. In the Late Triassic, the Funiu ancient land was uplifted which prevented source material from the Qinling Orogen. Owing to the Indosinian orogeny, the strata to the east of the North China Craton were uplifted and eroded. The Yichuan Basin received detrital material from the North China Craton.


2019 ◽  
Vol 156 (9) ◽  
pp. 1565-1586 ◽  
Author(s):  
Chaohui Liu ◽  
Guochun Zhao ◽  
Fulai Liu ◽  
Jia Cai

AbstractThe Bengbu area in the southeastern North China Craton (NCC) consists predominantly of Archean–Palaeoproterozoic (gneissic) granitoids with minor supracrustal rocks (the Fengyang and Wuhe groups). This study presents new zircon laser ablation – inductively coupled plasma – mass spectrometry U–Pb and Lu–Hf isotopic data and trace-element contents for these granitoids, which improve understanding the Archean–Palaeoproterozoic crustal evolution of the NCC. Magmatic zircon U–Pb data reveal that zircons in the (gneissic) granitoids were generated by multi-stage events at 2.93, 2.73, 2.53–2.52 and 2.18–2.13 Ga. Metamorphic zircon U–Pb data obtained from these rocks show two distinct metamorphic ages of 2.49–2.52 and 1.84 Ga, suggesting that the Bengbu area experienced a regional metamorphic event at the end of the Neoarchean Era and encountered reworking by a tectonothermal event associated with the formation of the Palaeoproterozoic Jiao-Liao-Ji Belt. Trace-element compositions of magmatic zircons reveal the highest Ti concentrations (8.08±3.38 ppm) and growth temperatures (718±44 °C) for the zircons aged 2.13–2.17 Ga and an increase in zircon U/Yb ratios from 2.93 Ga (0.34±0.12) through 2.73 Ga (0.96±0.42) to 2.53 Ga (1.05±0.46), but an evident decrease at 2.17–2.13 Ga (0.61±0.40 ppm). Similar Palaeoarchean xenocrystic and detrital zircons with negativeɛHf(t) values, late Mesoarchean magmatic zircons with juvenile Hf isotopic features, early Neoarchean magmatic zircons with model ages of 2.9–3.0 Ga, and two regional metamorphic events at 2.52–2.48 and 1.88–1.80 Ga in the Bengbu and Jiaobei areas indicate a Palaeoarchean–Mesoarchean micro-continent entrained in the Jiao-Liao-Ji Belt at the southeastern NCC.


Minerals ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 388
Author(s):  
Cheng Wang ◽  
Yongjun Shao ◽  
Kuanxin Huang ◽  
Haodi Zhou ◽  
Jianguo Zhang ◽  
...  

The Xiajinbao gold deposit is located at the northern margin of the North China Craton. Hydrothermal pyrites belonging to three stages were identified: Py1; Py2; and Py3. Geochemical study of these pyrites was conducted using electron probe microanalysis and laser ablation inductively coupled plasma mass spectrometry to investigate the distributions of minor and trace elements, constrain pyrite genesis, and to obtain an improved understanding of the ore-forming processes. Py1 and Py2 contain high concentrations of Au and are interpreted to have been deposited from fluids from a dominantly magmatic source. Py3 grains have the lowest Co/Ni ratios. All generations of pyrite were deposited by mixing of meteoric waters with magmatic-hydrothermal fluids. Boiling of early ore-forming fluids led to the precipitation of Py1 and gold. Decreasing fO2 in the ore-forming system resulted in the formation of Py2 and gold. Fluid mixing was the dominant controlling factor for the precipitation of Py3 together with small amounts of gold.


Minerals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 99
Author(s):  
Longxue Li ◽  
Qingye Hou ◽  
Dingling Huang ◽  
Xinyu Wang

The late Palaeozoic was an important period of tectonic evolution for the northern margin of the North China Craton (NCC). The source(s) and tectonic setting of early Permian granitoid rocks emplaced along the northern margin of the NCC are still unclear. These granitoids formed between ~295.4–276.1 Ma (uncertainties ranging from ±1.5 to ±7.8 Ma) according to zircon laser ablation inductively coupled mass spectrometry (LA-ICP-MS) and sensitive high-resolution ion microprobe (SHRIMP) U-Pb data. The Dadongou (DDG) pluton is an A1-type granite and the Dananfangzi (DNFZ) pluton is an A2-type granite. The Erdaowa (EDW), Lisicun (LSC), Wuhai (WH) and Gehuasitai (GHST) plutons are I-type granites. The Yuanbaoshan (YBS) dykes are diorite and syenodiorite. All the granitoids are enriched in large ion lithophile elements and light rare earth elements, depleted in high field strength elements and have negative εNd(t) and εHf(t) values. The A1-type granite was formed by the melting of the mafic crust. The A2-type granite was derived from partial melting of tonalite gneiss from the NCC crust and mantle materials. The EDW, LSC, WH and GHST granites mainly originated from partially melted granulite, with some mantle input. The YBS dykes are formed by the magma mixing of hot mantle melt and the relatively cold crustal magma. The northern margin of the NCC experienced anorogenic and collision tectonic stages, and the structural setting started to transform to post-collision at the later period of early Permian.


Author(s):  
Sarah C. Swan ◽  
John D.M. Gordon ◽  
Beatriz Morales-Nin ◽  
Tracy Shimmield ◽  
Terrie Sawyer ◽  
...  

Otoliths were obtained from Nezumia aequalis, a small macrourid that is widely distributed throughout the Atlantic and Mediterranean—two very different physical environments. Microchemical analysis of the otoliths was carried out using solution-based inductively coupled plasma mass spectrometry of whole otoliths. Significant differences between fish populations were found for concentrations of the elements Li and Sr. Only 54% of the samples were correctly classified by area using discriminant analysis. Otolith samples from the Reykjanes Ridge were most easily distinguished. The results are discussed in relation to trace element concentrations in the waters of the north-eastern Atlantic Ocean and the Mediterranean Sea.


2021 ◽  
pp. 1-27
Author(s):  
Aranya Sen ◽  
Koushik Sen ◽  
Amitava Chatterjee ◽  
Shubham Choudhary ◽  
Alosree Dey

Abstract The Himalaya is characterized by the presence of both pre-Himalayan Palaeozoic and syn-Himalayan Cenozoic granitic bodies, which can help unravel the pre- to syn-collisional geodynamics of this orogen. In the Bhagirathi Valley of Western Himalaya, such granites and the Tethyan Himalayan Sequence (THS) hosting them are bound to the south by the top-to-the-N extensional Jhala Normal Fault (JNF) and low-grade metapelite of the THS to its north. The THS is intruded by a set of leucocratic dykes concordant to the JNF. Zircon U–Pb laser ablation multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS) geochronology of the THS and one leucocratic dyke reveals that the two rocks have a strikingly similar age distribution, with a common and most prominent age peak at ~1000 Ma. To the north of the THS lies Bhaironghati Granite, a Palaeozoic two-mica granite, which shows a crystallization age of 512.28 ± 1.58 Ma. Our geochemical analysis indicates that it is a product of pre-Himalayan Palaeozoic magmatism owing to extensional tectonics in a back-arc or rift setting following the assembly of Gondwana (500–530 Ma). The Cenozoic Gangotri Leucogranite lies to the north of Bhaironghati Granite, and U–Pb dating of zircon from this leucogranite gives a crystallization age of 21.73 ± 0.11 Ma. Our geochemical studies suggest that the Gangotri Leucogranite is a product of muscovite-dehydration melting of the lower crust owing to flexural bending in relation to steepening of the subducted Indian plate. The leucocratic dykes are highly refracted parts of the Gangotri Leucogranite that migrated and emplaced along extensional fault zones related to the JNF and scavenged zircon from the host THS during crystallization.


2018 ◽  
Vol 16 (4) ◽  
pp. 622-634 ◽  
Author(s):  
Kaveh Pazand ◽  
Davoud Khosravi ◽  
Mohammad Reza Ghaderi ◽  
Mohammad Reza Rezvanianzadeh

Abstract Geochemical and hydrogeochemical studies were conducted to assess the origin and geochemical mechanisms driving lead enrichment in groundwaters of semi-arid regions in Central Iran. In this study, 149 water samples were analyzed using inductively coupled plasma mass spectrometry (ICP-MS). Concentrations of Pb and As in about 68% and 27% of the samples, respectively, exceeded WHO guidelines. Analyzing the results of ICP-MS of parental rocks and aquifer sediments shows that unweathered volcanic rocks were the primary source for lead mobilizing to groundwaters.


2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Yan Wang ◽  
Yi-Zeng Yang ◽  
Wolfgang Siebel ◽  
He Zhang ◽  
Yuan-Shuo Zhang ◽  
...  

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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