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13 results on '"Mo, X. -X"'

5. Tracing the provenance of inherited zircons from peraluminous granites in the Lhasa Terrane and its paleogeographic implications

Author

Zhu, D. C., Zhao, Z. D., Niu, Y. L., Wang, Q., Dilek, Y., Guan, Q., Yongsheng Liu, and Mo, X. X.

Subjects
Peraluminous granites, Paleogeography, U-Pb ages of inherited zircons, Lhasa Terrane, Lhasa-Australian connection
Abstract

Peraluminous granites with abundant zircon inheritance are derived from partial melting of Al-rich rocks (e.g. metapelite). Thus the U-Pb age data of inherited zircons from peraluminous granites provide insights into provenance of clastic sediments in their source region, as do the detrital zircons from sedimentary rocks (and their metamorphosed equivalents). This paper reports the whole-rock geochemical and zircon U-Pb geochronological data (95 analyses) of the Early Jurassic peraluminous granites in the central Lhasa subterrane. These data, in combination with the existing data of inherited zircons (104 analyses) from the Permian and Late Triassic peraluminous granites currently available in the central Lhasa subterrane, are used to characterize the inherited zircon signature of the Lhasa Terrane. These granites belong to strongly peraluminous S-type granites, which contain abundant inherited zircons that define two main age populations of 1250~1100Ma (peak at 1181±14Ma) and 550~450Ma (peak at 494±7Ma), comparable to the ca. 1170Ma age population defined by detrital zircons from Paleozoic sedimentary rocks and the emplacement timing of Cambrian volcanic rocks in the Lhasa Terrane, respectively. The ca. 1170Ma age population defined by inherited and detrital zircons in the Lhasa Terrane differs significantly from the age distributions (peak at ca. 960Ma) defined by detrital zircons from Neoproterozoic-Paleozoic sedimentary rocks in the western Qiangtang, Amdo, and Tethyan Hiamalaya in southern Tibet. We propose that the ca. 1181Ma inherited zircons from peraluminous granites in the central Lhasa subterrane were most likely derived from the Albany-Fraser orogenic belt in southwestern Australia and Wilkes Province in East Antarctica, as do the coeval detrital zircons from Paleozoic sedimentary rocks in the Lhasa Terrane, and that the ca. 494Ma inherited zircons might have been sourced from both the Western Australia and Lhasa Terrane itself. This paper provides evidence of U-Pb dating on inherited zircons from peraluminous granites for the paleogeographic connection between the Lhasa Terrane and northern Australia. Our studies on the geology of the Lhasa Terrane indicate that a combined in-situ U-Pb dating on inherited zircons from peraluminous granites and detrital zircons from Paleozoic sedimentary rocks can provide important constraints on paleogeography and tectonomagmatic evolution of other microcontinents along the northern margin of Gondwana.

Published
2011

8. Tracing the Indian Ocean mantle domain through time: isotopic results from old west Indian, east Tethyan, and south Pacific seafloor

Author

Mahoney, J. J., Frei, R., Tejada, M. L. G., Mo, X. X., Leat, P. T., NaGler, T. F., Mahoney, J. J., Frei, R., Tejada, M. L. G., Mo, X. X., Leat, P. T., and NaGler, T. F.

Abstract

The isotopic difference between modern Indian Ocean and Pacific or North Atlantic Ocean ridge mantle (e.g. variably lower 206Pb/204Pb for a given εNd and 208Pb/204Pb) could reflect processes that occurred within a few tens of millions of years preceding the initial breakup of Gondwana. Alternatively, the Indian Ocean isotopic signature could be a much more ancient upper-mantle feature inherited from the asthenosphere of the eastern Tethyan Ocean, which formerly occupied much of the present Indian Ocean region. Age-corrected Nd, Pb, and Sr isotopic data for 46–150 Ma seafloor lavas from sites in the western Indian Ocean and ocean-ridge-type Tethyan ophiolites (Masirah, Yarlung–Zangpo) reveal the presence of both Indian-Ocean-type compositions and essentially Pacific–North Atlantic-type signatures. In comparison, Jurassic South Pacific ridge basalts from Alexander Island, Antarctica, possess normal Pacific–North Atlantic-type isotopic ratios. Despite the very sparse sampling of old seafloor, the age-corrected εNd(t) values of the old Indian Ocean basalts cover a greater range than seen for the much more thoroughly sampled present-day spreading axes and islands within the Indian Ocean (e.g. 18 εNd units for basalts in the 60–80 Ma range vs 15 εNd units for 0–10 Ma ones). The implications of these results are that the upper mantle in the Indian Ocean region is becoming increasingly well mixed through time, and that the Indian Ocean mantle domain may not greatly pre-date the age of earliest spreading in the Indian Ocean.

Published
1998

11. Post-collisional ultrapotassic rocks in Lhasa block, Tibetan plateau: Spatial and temporal distribution and its' implications

Author

Zhao, Z. D., Mo, X. X., Nomade, S., Paul Renne, Zhou, S., Dong, G. C., Wang, L. L., Zhu, D. C., Liao, Z. L., Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Paléocéanographie (PALEOCEAN), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)

Subjects
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

13. Tracing the Indian Ocean Mantle Domain Through Time: Isotopic Results from Old West Indian, East Tethyan, and South Pacific Seafloor

Author

Mahoney, J. J., Frei, R., Tejada, M. L. G., Mo, X. X., Leat, P. T., NäGler, T. F., Mahoney, J. J., Frei, R., Tejada, M. L. G., Mo, X. X., Leat, P. T., and NäGler, T. F.

Abstract

The isotopic difference between modern Indian Ocean and Pacific or North Atlantic Ocean ridge mantle (e.g. variably lower 206Pb/204Pb for a given εNd and 208Pb/204Pb) could reflect processes that occurred within a few tens of millions of years preceding the initial breakup of Gondwana. Alternatively, the Indian Ocean isotopic signature could be a much more ancient upper-mantle feature inherited from the asthenosphere of the eastern Tethyan Ocean, which formerly occupied much of the present Indian Ocean region. Age-corrected Nd, Pb, and Sr isotopic data for 46-150 Ma seafloor lavas from sites in the western Indian Ocean and ocean-ridge-type Tethyan ophiolites (Masirah, Yarlung-Zangpo) reveal the presence of both Indian-Ocean-type compositions and essentially Pacific-North Atlantic-type signatures. In comparison, Jurassic South Pacific ridge basalts from Alexander Island, Antarctica, possess normal Pacific-North Atlantic-type isotopic ratios. Despite the very sparse sampling of old seafloor, the age-corrected εNd(t) values of the old Indian Ocean basalts cover a greater range than seen for the much more thoroughly sampled present-day spreading axes and islands within the Indian Ocean (e.g. 18 εNd units for basalts in the 60-80 Ma range vs 15 εNd units for 0-10 Ma ones). The implications of these results are that the upper mantle in the Indian Ocean region is becoming increasingly well mixed through time, and that the Indian Ocean mantle domain may not greatly pre-date the age of earliest spreading in the Indian Ocean

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