Whilst the topographic relief of the Tibetan Plateau’s northeast margin reflects recent Himalayan Orogenesis, its position and geometry reflect much older structures that developed during the Indosinian Orogeny c.200...Whilst the topographic relief of the Tibetan Plateau’s northeast margin reflects recent Himalayan Orogenesis, its position and geometry reflect much older structures that developed during the Indosinian Orogeny c.200Ma. The Indosinian Orogeny was responsible for closure and shortening of the Songpan Garzê Basin, a Palaeo\|Tethyan relict, during accretion of the Cimmerian Continental Chain to the southern margin of Laurasia. Sandwiched between Laurasia and the Cimmerian fragments of the Qangtang (North Tibet) and Yangtze (South China) blocks, this basin evolved into the Songpan Garzê Fold Belt—a major accretionary prism which now forms the northeast portion of the Tibetan Plateau.展开更多
The Ordovician conodont faunal provinces were previously divided into the Midcontinent and Atlantic Faunal Regions situated respectively in low and high latitudes, where warm- and cold-water type conodont faunas flour...The Ordovician conodont faunal provinces were previously divided into the Midcontinent and Atlantic Faunal Regions situated respectively in low and high latitudes, where warm- and cold-water type conodont faunas flourished respectively. According to the international correlation this paper proposes the third Ordovician conodont faunal region—Qinling Faunal Region, in which cold-water conodont faunas were well developed in the Early to middle Middle Ordovician and warm-water conodont faunas were well developed in the late Middle and Late Ordovician, indicating that the Qinling Region was situated in high latitudes earlier and in low latitudes later. The origin was only due to plate movement. In the Qinling Region the time interval of the change of the conodont fauna from the cold- to warm-water type was 4 Ma (from 474 to 470 Ma), during which the fauna geographically spanned 40° of latitudes, with a movement velocity of nearly 1.12 m/a, indicating that the high-latitude plates were divorced and reduced in the late Middle Ordovician, while the low-latitude plates were converged and accreted. According to the features of the conodont faunas, the Qinling Faunal Region can be divided into the North Tarim, Wudang, Scandic and Pingliang provinces.展开更多
文摘Whilst the topographic relief of the Tibetan Plateau’s northeast margin reflects recent Himalayan Orogenesis, its position and geometry reflect much older structures that developed during the Indosinian Orogeny c.200Ma. The Indosinian Orogeny was responsible for closure and shortening of the Songpan Garzê Basin, a Palaeo\|Tethyan relict, during accretion of the Cimmerian Continental Chain to the southern margin of Laurasia. Sandwiched between Laurasia and the Cimmerian fragments of the Qangtang (North Tibet) and Yangtze (South China) blocks, this basin evolved into the Songpan Garzê Fold Belt—a major accretionary prism which now forms the northeast portion of the Tibetan Plateau.
文摘The Ordovician conodont faunal provinces were previously divided into the Midcontinent and Atlantic Faunal Regions situated respectively in low and high latitudes, where warm- and cold-water type conodont faunas flourished respectively. According to the international correlation this paper proposes the third Ordovician conodont faunal region—Qinling Faunal Region, in which cold-water conodont faunas were well developed in the Early to middle Middle Ordovician and warm-water conodont faunas were well developed in the late Middle and Late Ordovician, indicating that the Qinling Region was situated in high latitudes earlier and in low latitudes later. The origin was only due to plate movement. In the Qinling Region the time interval of the change of the conodont fauna from the cold- to warm-water type was 4 Ma (from 474 to 470 Ma), during which the fauna geographically spanned 40° of latitudes, with a movement velocity of nearly 1.12 m/a, indicating that the high-latitude plates were divorced and reduced in the late Middle Ordovician, while the low-latitude plates were converged and accreted. According to the features of the conodont faunas, the Qinling Faunal Region can be divided into the North Tarim, Wudang, Scandic and Pingliang provinces.
