Discovery of a sheeted dike complex in the northern Yangtze craton and its implications for craton evolution

Abstract

The Miaowan (庙湾) ophiolite is a highly dismembered ophiolitic complex cropping out near the northern margin of the Yangtze craton. The rocks of this complex consist of, from bottom to top, harzburgite tectonite locally containing podiform chromite, dunite, layered and isotropic gabbro, a sheeted dike complex (SDC), meta-pillow lavas with chert pods and layers, and tectonically intercalated marble. The SDC is a very important and significant part of the Miaowan ophiolitic sequence, and grades downward into gabbro and ultramafic rocks, and upward into meta-pillow lavas. Some dikes preserve one-way chilled margins, typical of extensional ophiolitic settings, whereas most preserve double chilled margins, in cases where the chilling direction can be determined. The SDC is mainly composed of meta-diabase (dolerite), meta-plagiogranite, and small amounts of meta-gabbro and ultramafic rocks. LA-ICP-MS zircon dating yields an upper intercept age of 1 026±79 Ma for one meta-plagiogranite, 1 043±23 Ma for a second meta-plagiogranite and 1 096±32 Ma for one meta-gabbro at the bottom of the SDC, suggesting formation of the SDC at circa 1 026–1 096 Ma, consistent with the recently determined formation age of the Miaowan ophiolite. Sparse geochemical data on the meta-diabase indicate that the protolith was a sub-alkaline, low-potassium tholeiite similar to mid-ocean ridge basalt (MORB). The chondrite-normalized rare earth element (REE) patterns of the meta-diabase are generally flat ((La/Yb)N=0.56–0.94), with a slight depletion in LREE, but no obvious Eu anomalies. Given that the meta-plagiogranites show evidence of formation in a suprasubduction zone environment, we suggest that the basalts were originally island arc tholeiites, perhaps formed in an extensional forearc setting. The geochemistry of the meta-diabase and plagiogranite from the sheeted dikes, together with regional relationships, all agree with the previous interpretations that the Miaowan ophiolite formed in a suprasubduction zone setting.

Keywords

ophiolite / sheeted dike complex / Yangtze craton / Rodinia

References

[1] Amri I., Benoit M., Ceuleneer G.. Tectonic Setting for the Genesis of Oceanic Plagiogranites: Evidence from a Paleospreading Structure in the Oman Ophiolite. Earth and Planetary Science Letters, 1996, 139(1–2): 177-194.

[2] Coleman R. G., Peterman Z. E.. Oceanic Plagiogranite. Journal of Geophysical Research, 1975, 80(8): 1099-1108.

[3] Coleman R. G., Donato M. M.. Barker F.. Oceanic Plagiogranite Revisited. Trondhjemites, Dacites and Related Rocks, 1979, Amsterdam: Elsevier 149 168

[4] Dilek, Y., Moores, E. M., Furnes, H., 1998. Structure of Modern Oceanic Crust and Ophiolites and Implications for Faulting and Magmatism at Oceanic Spreading Centers. In: Buck, R., Karson, J., Delaney, P., et al., eds., Faulting and Magmatism at Mid-Ocean Ridges. American Geophysical Union Monograph, 106: 219–266

[5] Dilek Y., Furnes H.. Ophiolite Genesis and Global Tectonics: Geochemical and Tectonic Fingerprinting of Ancient Oceanic Lithosphere. Geological Society of America Bulletin, 2011, 123(3–4): 387-411.

[6] Flagler P. A., Spray J. G.. Generation of Plagiogranite by Amphibolite Anatexis in Oceanic Shear Zones. Geology, 1991, 19(1): 70-73.

[7] France L., Koepke J., Ildefonse B., . Hydrous Partial Melting in the Sheeted Dike Complex at Fast Spreading Ridges: Experimental and Natural Observations. Contributions to Mineralogy and Petrology, 2010, 160: 683-704.

[8] Gao S., Ling W. L., Qiu Y. M., . Contrasting Geochemical and Sm-Nd Isotopic Compositions of Archean Metasediments from the Kongling High-Grade Terrain of the Yangtze Craton: Evidence for Cratonic Evolution and Redistribution of REE during Crustal Anatexis. Geochimica et Cosmochimica Acta, 1999, 63(13–14): 2071-2088.

[9] Gass, I. G., 1990. Ophiolites and Oceanic Lithosphere. In: Malpas, J., Moores, E. M., Panayiotou, A., et al., eds., Ophiolites, Oceanic Crustal Analogues. Proceedings of the Symposium “Troodos 1987”, Nicosia. 1–10

[10] Glassley W.. Geochemistry and Tectonics of the Grescent Volcanic Rocks, Olympic Peninsula, Washington. Geologic Science of American Bulletin, 1974, 85: 785-794.

[11] Janney P. E., Castillo P. R.. Basalts from the Central Pacific Basin: Evidence for the Origin of Cretaceous Igneous Complexes in Jurassic Western Pacific. Journal of Geophysical Research, 1996, 101: 2875-2893.

[12] Koepke J., Feig S. T., Snow J., . Petrogenesis of Oceanic Plagiogranites by Partial Melting of Gabbros: An Experimental Study. Contributions to Mineralogy and Petrology, 2004, 146(4): 414-432.

[13] Koepke J., Berndt J., Feig S. T., . The Formation of SiO₂-Rich Melts within the Deep Oceanic Crust by Hydrous Partial Melting of Gabbros. Contributions to Mineralogy and Petrology, 2007, 153: 67-84.

[14] Kusky T. M., Wang L., Dilek Y., . Application of the Modern Ophiolite Concept with Special Reference to Precambrian Ophiolites. Science China (Series D), 2011, 54: 315-341.

[15] Li W. X., Li X. H.. Adakite Granites within the NE Jiangxi Ophiolites, South China: Geochemical and Nd Isotopic Evidence. Precambrian Research, 2003, 112: 29-44.

[16] Li W. X., Li X. H.. Rock Types and Tectonic Significance of the Granitoids Rocks within Ophiolites. Advance in Earth Sciences, 2003, 18: 392-397.

[17] Li Z. X., Zhang L., Powell C. M.. South China in Rodinia: Part of the Missing Link between Australia-East Antarctica and Laurentia?. Geology, 1995, 23(5): 407-410.

[18] Liu X. M., Gao S., Diwu C. R., . Precambrian Growth of Yangtze Craton as Revealed by Detrital Zircon Studies. American Journal of Science, 2008, 308(4): 421-468.

[19] Liu Y. S., Hu Z. C., Gao S., . In Situ Analysis of Major and Trace Elements of Anhydrous Minerals by LA-ICP-MS without Applying an Internal Standard. Chemical Geology, 2008, 257(1–2): 34-43.

[20] Liu Y. S., Gao S., Hu Z. C., . Continental and Oceanic Crust Recycling-Induced Melt-Peridotite Interactions in the Trans-North China Orogen: U-Pb Dating, Hf Isotopes and Trace Elements in Zircons of Mantle Xenoliths. Journal of Petrology, 2010, 51(1–2): 537-571.

[21] Liu Y. S., Hu Z. C., Zong K. Q., . Reappraisement and Refinement of Zircon U-Pb Isotope and Trace Element Analyses by LA-ICP-MS. Chinese Science Bulletin, 2010, 55: 1535-1546.

[22] Lu Y. F.. Geokit: A Geochemical Software Package Constructed by VAB. Geochemistry, 2004, 33(5): 459-464.

[23] Ludwig, K. R., 2003. User’s Manual for Isoplot/EX Version 3.00: A Geochronological Toolkit for Microsoft Excel. Berkeley Geochronology Center Special Publication 4, California. 1–70

[24] Ma D. Q., Li Z. C., Xiao Z. F.. The Constitute, Geochronology and Geologic Evolution of the Kongling Complex, Western Hubei. Acta Geoscientica Sinica, 1997, 18(3): 233-241.

[25] O’Connor J. T.. A Classification for Quartz-Rich Igneous Rocks Based on Feldspar Ratios. U. S. Geological Survey Professional Paper, 1965, 525B: 79-84.

[26] Pearce T. H., Gorman B. E., Birkett T. C.. The TiO₂-K₂O-P₂O₅ Diagram: A Method of Discrimination between Oceanic and Non-Oceanic Basalts. Earth and Planetary Science Letters, 1975, 24(3): 419-426.

[27] Pearce J. A.. Thorpe R. S.. Trace Element Characteristics of Lavas from Destractive Plate Boundaries. Andesites, 1982, New York: Wiley 528 548

[28] Pearce J. A.. Hawkesworth C. J., Norry M. J.. The Role of Subcontinental Lithosphere in Paragenesis at Destructive Plate Margins. Continental Basalts and Mantle Xenoliths (Shiva Geology Series), 1983, Boston: Birkhäuser Boston 230 249

[29] Pearce J. A., Harris N. B. W., Tindle A. G.. Trace Element Discrimination Diagrams for the Tectonic Interpretation of Granitic Rocks. Journal of Petrology, 1984, 25(4): 956-983.

[30] Peng S. B., Li C. N., Kusky T. M., . The Discovery and Its Tectonic Significance of the Proterozoic Miaowan Ophiolites in the Southern Huangling Anticline Area, Western Hubei Province, China. Geological Bulletin of China, 2010, 29(1): 8-20.

[31] Peng S. B., Kusky T. M., Jiang X. F., . Geology, Geochemistry and Geochronology of the Miaowan Ophiolite, Yangtze Craton: Implications for South China’s Amalgamation History with the Rodinian Supercontinent. Gondwana Research, 2012, 21(2–3): 577-594.

[32] Robinson P. T., Malpas J., Dilek Y., . The Significance of Sheeted Dike Complexes in Ophiolites. GSA Today, 2008, 18(11): 4-10.

[33] Rollinson H. R.. Using Geochemical Data: Evaluation, Presentation, Interpretation, 1993, New York: John Wiley & Sons 155

[34] Rollinson H.. New Models for the Genesis of Plagiogranites in the Oman Ophiolite. Lithos, 2009, 112(3–4): 603-614.

[35] Sun, S. S., McDonough, W. F., 1989. Chemical and Isotopic Systematics of Oceanic Basalts: Implications for Mantle Composition and Processes. In: Saunders, A. D., Norry, M. J., eds., Magmatism of the Ocean Basins. Geological Science of London Special Publication, 42: 313–345

[36] Wang J. P., Kusky T. M., Polat A., . Sea-Floor Metamorphism Recorded in Epidosites from the ca. 1.0 Ga Miaowan Ophiolite, Huangling Anticline, China. Journal of Earth Science, 2012, 23(5): 696-704.

[37] Wang X. F., Chen X. H., Zhang R. J., . Precious Geological Relic Sits Protection and Archean-Mesozoic Multiple Stratigraphic Division and Sea Level Change along Yangtze River, Three Gorges Area, 2002, Beijing: Geological Public House

[38] Winchester J. A., Floyd P. A.. Geochemical Discrimination of Different Magma Series and Their Differentiation Products Using Immobile Elements. Chemical Geology, 1977, 20: 325-343.