Late Paleogene lacustrine strata of the Suonahu Formation, mainly consisted of brownish red, brown and gray marl, mudstone, siltstone intercalated with gypsum and limestone, formed and outcrops widely in central Qiangtang, Hohxil and southern Kunlun Blocks, northern Tibetan Plateau. Isotopic ages of volcanic rocks overlying and beneath Late Paleogene lacustrine strata indicate that the Suonahu Formation in Shuanghu and its adjacent areas, central Qiangtang Block formed in 41.1±0.8~32.5±0.3 Ma. Similar lacustrine deposits of the Suonahu Formation gradually change to the Yaxicuo Group in eastern Hohxil Block. Samples were collected in the Upper Suonahu Formation along a wide trench in Shuanghu. Detrital zircons were selected in brown marl, brown clay and gray clay samples, and LA-MC-ICP-MS U-Pb isotoic dating were finished for detrital zircons from the three samples, while more samples were analyzed for determination of carbon and oxygen isotopes of marl, clay and limestone from the Suonahu Formation in Shuanghu trench. These data, together with field geology, reveal well the origin of detrital zircons, paleostream and paleoelevation in northern Tibetan Plateau. Most detrital zircons of the Suonahu Formation in Shuanghu trench are magmatic zircons, and four statistical peaks of U-Pb ages of these detrital zircons occur in 280~200Ma, 780~830Ma, 1920~1790Ma, 2600~2360Ma for all the samples. The extensive distribution of lacustrine deposits of Suonahu Formation indicate that paleolakes in southern East Kunlun, Hohxil and Shuanghu areas were linked by water passages in Late EoceneEarly Oligocene, so detrital zircons of Suonahu Formation in Shuanghu might come from source rocks in the East Kunlun, Hohxil and Qiangtang blocks. By comparing to regional data of geology and chronology, it is inferred that detrital zircons with peak ages in 280~200Ma come from the Late PermianTriassic magmatic rocks in Central Qiangtang Uplift, and detrital zircons with peak ages in ~800Ma, ~1800Ma and ~2500Ma came from the Middle NeoProterozoic, Late PaleoProterozoic and Ending ArcheanInitial Proterozoic magmatic rocks, respectively, in East Kunun orogenic belt. Early Precambrian detrital zircons from Suonahu Formation in Shuanghu trench scatter linearly in the UPb isotopic diagram with intercept ages in 1883±51~1837±12 Ma and 2483±24~2520±37 Ma, corresponding to 2 periods of Early Precambrian magmatic intrusion in East Kunlun Mts. It is further inferred that Late Paleogene paleofloods formed in East Kunlun Mts., captured the Precambrian magmatic zircons, moved southward across Hohxil and northern Qiangtang, and downloaded the detrital zircons in lacustrine deposits of the Suonahu Formation in Shuanghu paleo-lake. Carbon and oxygen isotopes of lacustrine deposits of the Suonahu Formation indicate that paleo-elevation of the Shuanghu area was 3427~3510 m in late Eocene (35~34Ma), which is similar to paleo-elevation inferred paleo-crust thickness by the Airy balance modeling.