Abstract
Lower crustal xenoliths brought up rapidly by basaltic magma onto the earth surface may provide direct information on the lower crust. The main purpose of this research is to gain an insight into the rheology of the lower crust through the detailed study of lower crustal xenoliths collected from the Hannuoba basalt, North China. The lower crustal xenoliths in this area consist mainly of two pyroxene granulite, garnet granulite, and light-colored granulite, with a few exception of felsic granulite. The equilibration temperature and pressure of these xenoliths are estimated by using geothermometers and geobarometers suitable for lower crustal xenoliths. The obtained results show that the equilibration temperature of these xenoliths is within the range of 785–900°C, and the equilibrium pressure is within the range of 0.8–1.2 GPa, corresponding to a depth range of 28–42 km. These results have been used to modify the previously constructed lower crust-upper mantle geotherm for the studied area. The differential stress during the deformation process of the lower crustal xenoliths is estimated by using recrystallized grain-size paleo-piezometer to be in the range of 14–20 MPa. Comparing the available steady state flow laws for lower crustal rocks, it is confirmed that the flow law proposed by Wilks et al. in 1990 is applicable to the lower crustal xenoliths studied in this paper. The strain rate of the lower crust estimated by using this flow law is within the range of 10−13–10−11 s−1, higher than the strain rate of the upper mantle estimated previously for the studied area (10−17–10−13 s−1); the equivalent viscosity is estimated to be within the range of 1017–1019Pa·s, lower than that of the upper mantle (1019–1021 Pa·s). The constructed rheological profiles of the lower crust indicate that the differential stress shows no significant linear relation with depth, while the strain rate increases with depth and equivalent viscosity decrease with depth. The results support the viewpoint of weak lower continental crust.
Similar content being viewed by others
References
Griffin W L, O’Reilly S Y. The composition of the lower crust and the nature of the continental Moho — Xenolith evidence. In: Nixon P H, ed. Mantle Xenolith. New York N Y: John Wiley & Sons Ltd, 1987. 413–430
Rudnick R L. Xenoliths—Samples of the lower continental crust. In: Fountain D M., Arculus R J, Kay R W, eds. Continental Lower Crust. Amsterdam, London, New York, Tokyo: Elsevier, 1992. 269–316
O’Reilly S Y, Griffin W L. 4-D lithosphere mapping: methodology and examples. Tectonophysics, 1996, 262(1): 3–18
Xie M Z, Feng J L, Zhang G L. Discovery of granulite xenoliths in Hannuoba basalts. J Hebei Geological College (in Chinese), 1993, 16(6): 587–593
Fan Q C, Liu R X. High temperature granulite xenoliths in Hannuoba basalts. Chin Sci Bull (in Chinese), 1996, 41(3): 235–238
Fan Q C, Liu R X, Li H M, et al. Zircon chronology and REE geochemistry of granulite xenolith at Hannuoba. Chin Sci Bull, 1998, 43(18): 1510–1515
Chen S H, Zhang G H, Zhou X H, et al. Petrological investigation on the granulite xenoliths from Hannuoba basalts, northern Sino-Korean craton. Acta Petrol Sin (in Chinese), 1998, 14(3): 366–380
Zhang G H, Zhou X H, Sun M, et al. Sr, Nd and Pb isotopic characteristics of granulite and pyroxenite xenoliths in Hannuoba basalts, Hebei Province, and their implications for geologic processes. Acta Petrol Sin (in Chinese), 1998, 14: 190–197
Shi L B, Lin C Y, Chen X D. A xenolith-derived geotherm for the lower crust and upper mantle beneath Hanuoba area, Hebei Province, China and its geologic implications. Seismol Geol (in Chinese), 2000, 22(1): 37–46
Chen S, O’Reilly S Y, Zhou X, et al. Thermal and petrological structures of the lithosphere beneath Hannuoba, Sino-Korean craton, China — Evidence from xenoliths. Lithos, 2001, 56(2): 267–301
Liu Y S, Gao S, Liu X M, et al. Thermodynamic evolution of lithosphere of the North China craton: Records from lower crust and upper mantle xenoliths from Hannuoba. Chin Sci Bull, 2004, 49(10):1055–1062
Wells P R A. Pyroxene thermometry in simple and complex systems. Contrib Mineral Petrol, 1977, 62(1): 129–139
Wood B J. Solubility of alumina in orthopyroxene coexisting with garnet. Contrib Mineral Petrol, 1974, 45(1): 1–15
Brey G P, Kohler T. Geothermobarometry in four-phase lherzolites II. New thermobarometer and practical assessment of existing thermobarometer. J Petrol, 1990, 31: 1353–1378
Witt G E, Seck H A. Solubility of Ca and Al in orthopyroxene from spinel peridotite: An improved version of an empirical geothermometer. Contrib Mineral Petrol, 1991, 106(4): 431–439
Xu Y G. Geothemometers suitable for mantle xenoliths. Acta Petrol Sin (in Chinese), 1993, 9(2): 167–179
Nickel K G, Green D H. Empirical geothermobarometry for garnet peridotites and implications for the nature of the lithosphere, kimberlites and diamond. Earth Planet Sci Lett, 1985, 73(2): 158–170
Rushmer T. Experimental high-pressure granulites: some applications to natural mafic xenoliths and Archean granulite terranes. Geology, 1993, 21: 411–414
Wood B J, Bano S. Garnet-orthopyroxene and orthopyroxeneclino-pyroxene relationships in simple and complex systems. Contrib Mineral Petrol, 1973, 42(1): 109–124
McCarthy T C, Patino Douce A E. Empirical calibration of the silica-Ca-tschermak’s-anorthite (SCAn) geobarometer. J Metamor Geol, 1998, 16: 675–686
Huang X L, Xu Y G, Wang R C, et al. The Nushangranulite xenoliths from Anhui Province, China: Mineralogical characteristics, the lower crustal geothrm and their implications for genesis. Acta Petrol Sin (in Chinese), 2002, 18(3): 383–391
Xu Y G, Lin C Y, Shi L B. The geotherm of the lithosphere beneath Qilin, SE China: A reappraisal and implication for P-T estimation of Fe-rich pyroxenites. Lithos, 1999, 47: 181–193
Rutter E H, Brodie K H. Rheology of the lower crust. In: Fountain D M, Arculus R J, Kay R W, eds. Continental Lower Crust. Amsterdam, London, New York, Tokyo: Elsevier. 201–267
Twiss R J. Theory and applicability of a recrystallized grain size paleopiezometer. Pure Appl Geophys, 1977, 115: 227–244
Mercier J C C. Olivine and pyroxene. In: Wenk H R, ed. Preferred orientation of metals and Rocks: An Introduction to Modern Texture analysis. New York: Academic Press Inc, 1985. 407–430
Post A, Tullis J. A recrystallized grain size piezometer for experimentally deformed feldspar aggregates. Tectonophysics, 1999, 303:159–173
Wilks K, Carter N L. Rheology of some continental lower crustal rocks. Tectonophysics, 1990, 182: 57–77
Carter N L, Tsenn M C. Flow properties of continental lithosphere, Tectonophysics, 1987, 136: 27–63
Ave Lallement H G, Mercier J-C C, Carter N L, et al. Rheology of the upper mantle: inferences from peridotite xenoliths. Tectonophysics, 1980, 70: 85–113
Cabanes N, Brique L. Hydration of an active shear zone: interaction between deformation, metasomatism and magmatasm. Earth Planet Sci Lett, 1987, 81: 233–244
Zhou Y S, He C R. Rheological parameters of crustal rocks and crustal rheology of North China. Seismol Geol (in Chinese), 2003, 25(1):109–122
Ross J V, Wilks K R. Effect of a third phase on the mechanical and microstructural evolution of a granulite. Tectonophys, 1995, 241:303–316
Ross J V, Wilks K R. Microstructure development in an experimentally sheared orthopyroxene granulite. Tectonophys, 1996, 256:83–100
Mackwell S J, Zinmermen M E, Kohlstedt D L. High temperature deformation of dry diabase with application to tectonics on Venus. J Geophys Res, 1998, 103: 975–984
Caristan Y. The transition from high temperature creep to fracture in Maryland diabase. J Geophys Res, 1982, 7: 6781–6790
He C R, Zhou Y S, Sang Z N. An experimental study of semi-brittle and plastic rheology of Panzhihua gabbro Sci China Ser D-Earth Sci, 2003, 46(7): 730–742
Lin C Y, Shi L B, He Y N. Rheological features of the upper mantle beneath North China. In: Liu R X ed. Collected Papers on the Features and Dynamics of the Lithosphere in Eastern China (in Chinese). Beijing: Seismological Press, 1990, 93–101
Lin C Y, Huang X L, Xu Y G, et al. Thermal structure and rheology of the upper mantle beneath Leizhou Peninsula, Guangdong Province, China. J Tropical Oceanogr (in Chinese), 2003, 22(2): 49–62
Meissner R, Mooney W. Weakness of the lower continental crust: a condition for delamination, uplift and escape. Tectonophysics, 296(1):47–60
Kirby S H, Kronenberg A K. Rheology of the lithosphere: selected topic. Rev Geophys, 1987, 25: 1219–1244
Kay R W, Mahlburg Kay S. Delamination and delamination magmatism. Tectonophysics, 1993, 219: 177–189
Gao Shan, Zhang Ben-ren, Jin Zhen-ming, et al. How mafic is the continental lower crust? Earth Planet Sci Lett, 1998, 161(1):101–117
Author information
Authors and Affiliations
Corresponding author
Additional information
Supported by Seismic Sciences Joint Foundation (Grant No. 103038)
Rights and permissions
About this article
Cite this article
Chen, X., Lin, C. & Shi, L. Rheology of the lower crust beneath the northern part of North China: Inferences from lower crustal xenoliths from Hannuoba basalts, Hebei Province, China. SCI CHINA SER D 50, 1128–1141 (2007). https://doi.org/10.1007/s11430-007-0047-3
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/s11430-007-0047-3