Zhang Y.-F.,LIAONING Technical University |
Liu J.-D.,LIAONING Technical University |
Xiao R.-G.,China University of Geosciences |
Wang S.-Z.,Liaoning Geological Survey for Chemical Industry |
And 2 more authors.
Diqiu Kexue - Zhongguo Dizhi Daxue Xuebao/Earth Science - Journal of China University of Geosciences | Year: 2010
SHRIMP zircon U-Pb dating results are firstly reported for the hyalotourmalites in Houxianyu borate deposit in order to determine its formation time. The zircons commonly have core-rim structures. Most cores show oscillatory zoning in CL and plane polarized light images, suggesting a magmatic detrital origin. The zircon without distinct structural change may represent a metamorphic origin. Magmatic detrital zircons and metamorphic zircons from three samples yield ages of 2 171-2 175 Ma and 1 894-1 906 Ma, respectively. Combined with geology and lithology, the protolith of hyalotourmalite is concluded to be the product of exhalation of submarine hot water caused by the magmatic activity with the magma derived from the depleted mantle source with crustal contamination in the cratonic rift environment, which occurred in the middle Palaeoproterozoic (2 171-2 175 Ma) and underwent the late metamorphism during a period of 1 894-1 906 Ma.
Liu J.,Liaoning Geological Survey for Chemical Industry |
Liu J.,LIAONING Technical University |
Xiao R.,China University of Geosciences |
Zhang Y.,Liaoning Geological Survey for Chemical Industry |
And 6 more authors.
Acta Geologica Sinica | Year: 2012
This paper focused on the zircon sensitive high resolution ion micro-probeU-Pb geochronology of the tourmalinites from boron-bearing series of borate deposits in Eastern Liaoning. The zircons commonly have core-rim structures, most cores show oscillatory zoning in cathodoluminescence and plane polarized light images, suggesting a magmatic detrital origin. Ages of the magmatic detrital zircons from the hyalotourmalite samples (NI3) and (NI4) are 2175 ± 5 Ma and 2171 ± 9 Ma, respectively. Moreover, metamorphic zircon from the sample (NI3) shows an age of 1906 ± 4 Ma. Zircon core and rim from the hyalotourmalite sample (N02) record ages of 2171 ± 6 Ma and 1889 ± 62 Ma, which are explained as indicating the formation and metamorphic ages. Combined with the geological and geochemical studies, it can be concluded that the tourmalinites are formed during sedimentary exhalative mineralizations in the mid-Paleoproterozoic (∼,2170 Ma) and underwent the métamorphism in the late-Paleoproterozoic (∼1900 Ma). The tourmalinites are the products of submarine acid volcanism in the extension rifting phase of the Liaoji Paleoproterozoic Rift, the rockforming materials of which are derived from the mantle sources with recycling crustal contamination. The emergence of tourmalinites not only indicates the mid-Paleoproterozoic tectonic-magmatic processes, but also provides impetus, heat and material sources for the mineralization of borate deposits in Eastern Liaoning.