Geochemistry and Petrogenesis of the ca. 2.5 Ga High-K Granitoids in the Southern North China Craton
Lei Li , Wenjian Zhai
Journal of Earth Science ›› 2019, Vol. 30 ›› Issue (3) : 647 -665.
Geochemistry and Petrogenesis of the ca. 2.5 Ga High-K Granitoids in the Southern North China Craton
Archean high-K granitoids, generally formed after tonalite-trondhjemite-granodiorite (TTGs), are important for understanding crustal reworking of ancient cratons. The Linshan Archean high-K granitoids from the southern Trans-North China Orogen (TNCO) provide a window into the continental crustal evolution of the North China Craton (NCC). They mainly consist of monzogranite and granodiorite which were formed during 2 542–2 503 Ma. The high-K granitoids have high SiO2 (65.86 wt.%–78.08 wt.%), K2O (3.29 wt.%–7.62 wt.%) and low P2O5 (0.01 wt.%–0.27 wt.%). They display right inclined REE patterns with negative Eu anomalies (Eu/Eu*=0.20–0.81). Their spider diagram is characterized by enrichment of Rb, K, Th, U and depletion of Nb, Ta, Zr, Ti. The rocks have positive and variable zircon e Hf(t) (+2.5 to +6.6) and whole-rock e Nd(t) (+0.7 to +4.5) with two-stage model ages (T DM2 Hf=2.87–2.64 Ga; T DM2 Nd=2.77–2.50 Ga) similar to those of the Archean TTG-type rocks, amphibolites and diorites in the area. These evidences suggest that the high-K granitoids were produced by partial melting of juvenile crustal rocks. The Linshan high-K granitoids show relatively high whole-rock zircon saturation temperatures (694–889 ºC) and low Sr/Y ratios (0.27–21.1), indicating low pressure partial melting. Combined with other geological evidences, the Linshan high-K granitoids are suggested to have been produced by partial melting of the continental crust in a post-collision extensional environment after an arc-continent collision. Thus, the NCC did not amalgamate together until ca. 2.5 Ga. Compiled zircon U-Pb ages and Hf isotopes reveal that the ca. 2.5 Ga magmatism represents reworking of the continental crust.
granitoids / petrogenesis / Neoarchean / North China Craton
| [1] |
Anhaeusser, C. R., 2014. Archaean Greenstone Belts and Associated Granitic Rocks—A Review. Journal of African Earth Sciences, 100. 684–732. https://doi.org/10.1016/j.jafrearsci.2014.07.019 |
| [2] |
|
| [3] |
|
| [4] |
|
| [5] |
|
| [6] |
|
| [7] |
|
| [8] |
|
| [9] |
|
| [10] |
|
| [11] |
|
| [12] |
|
| [13] |
|
| [14] |
|
| [15] |
|
| [16] |
|
| [17] |
|
| [18] |
|
| [19] |
|
| [20] |
|
| [21] |
|
| [22] |
|
| [23] |
|
| [24] |
|
| [25] |
|
| [26] |
|
| [27] |
|
| [28] |
|
| [29] |
|
| [30] |
|
| [31] |
|
| [32] |
|
| [33] |
|
| [34] |
|
| [35] |
|
| [36] |
|
| [37] |
|
| [38] |
|
| [39] |
|
| [40] |
|
| [41] |
|
| [42] |
|
| [43] |
|
| [44] |
|
| [45] |
|
| [46] |
|
| [47] |
|
| [48] |
|
| [49] |
|
| [50] |
|
| [51] |
|
| [52] |
|
| [53] |
|
| [54] |
|
| [55] |
|
| [56] |
|
| [57] |
|
| [58] |
|
| [59] |
|
| [60] |
|
| [61] |
|
| [62] |
|
| [63] |
|
| [64] |
|
| [65] |
|
| [66] |
|
| [67] |
|
| [68] |
Trap, P., Faure, M., Lin, W., et al., 2012. Paleoproterozoic Tectonic Evolution of the Trans-North China Orogen: Toward a Comprehensive Model. Precambrian Research, 222/223: 191–211. https://doi.org/10.1016/j.precamres.2011.09.008 |
| [69] |
|
| [70] |
|
| [71] |
|
| [72] |
|
| [73] |
|
| [74] |
|
| [75] |
|
| [76] |
|
| [77] |
|
| [78] |
|
| [79] |
|
| [80] |
|
| [81] |
|
| [82] |
|
| [83] |
|
| [84] |
|
| [85] |
|
| [86] |
|
| [87] |
|
| [88] |
|
| [89] |
|
| [90] |
|
| [91] |
|
| [92] |
|
| [93] |
|
| [94] |
|
| [95] |
|
| [96] |
|
| [97] |
|
| [98] |
|
| [99] |
|
| [100] |
|
| [101] |
|
| [102] |
|
| [103] |
|
| [104] |
|
| [105] |
|
| [106] |
|
| [107] |
|
| [108] |
|
| [109] |
|
/
| 〈 |
|
〉 |