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To determine the Late Palaeozoic evolution of the Lhasa terrane, we report the results of field mapping, petrological and fossil investigations, and U–Pb dating of detrital zircon grains (n = 474) from lower-greenschist-facies clastic rocks of the Lagar Formation in the Baruo area, Tibet. Our results indicate that the Lagar Formation was deposited during the Late Carboniferous to Early Permian in a shallow-marine environment on the northern margin of Gondwana. Glacial marine diamictites are common within the Lagar Formation and record glaciation of Gondwana during the Late Palaeozoic. Moreover, the detrital materials of the Lagar formation originated mostly from the collision orogenic belt. The ages of detrital zircon grains from the Lagar Formation make up five main groups with ages of 410–540 Ma, 550–650 Ma, 800–1100 Ma, 1600–1800 Ma, and 2300–2500 Ma, which display three characteristic age peaks at ~1150, 2390 and 2648 Ma. We tentatively suggest that the Lhasa terrane was a shallow-marine basin under the influence of the Gondwanan glaciation during the Late Carboniferous–Early Permian.

The time-synchronization has no ground time criterion in the model of autonomous time-synchronization, time precision keep on the navigation satellite itself. When can make GEO satellite as time norm, and use satellite-satellite chain to give other satellite. This paper design the navigation constellation of the new satellite-navigation-system, and configure the satellite clocks, simulate all kinds of constellation time-synchronization precision, educe the satellite clock configure scheme in the new navigation system. Due to the introduction of high-precision optical clocks, the overall time of the entire navigation constellations drift is smaller, the accuracy is much higher than the link between self-ordinary; and because the presence of high-precision clock, the time synchronization algorithm’s requirements are lower, general EKF can meet the requirements.