Northern Junggar Basin Research Articles

Small mammal assemblages and habitat distribution in the northern Junggar Basin, Xinjiang, China: a pilot survey

Small mammal assemblages were surveyed in five areas of the northern Junggar basin, Xinjiang, China, using standard trapping methods and index transects. 23 species were recorded. The relationships between habitats and the distribution of the main species were described at local scale in Baihaba, Altai mountains. Three types of assemblages were identified linked to (i) forest (Myodes rufocanus, Microtus agrestis, Myodes rutilus, Apodemus peninsulae, Sorex isodon), (ii) transitional areas and farmland (mixed pool of species including Apodemus uralensis), (iii) grassland (Ellobius tancrei, Microtus obscurus, Cricetulus migratorius). Additional species such as Microtus oeconomus could be found along small streams. At broader scale species composition was estimated in Kokehada, Nahenhobuke and Fuhai areas and compared. Although ecological gradients from mountain grasslands to cold semi-desert partly explain differences in assemblage composition on a regional scale, similar habitats at the same altitude may however harbour different assemblages. For example, Spermophilus erythrogenys was the dominant species of the Kokehada grassland and Microtus obscurus and Ellobius tancrei were dominant in Baihaba grassland. In conclusion, the need for multi-scale standard descriptions of small mammal assemblage distribution in the northern Junggar basin of China is pointed out

The Tunggurian Stage of the Continental Miocene in China

Abstract: The Tunggurian Age was nominated in 1984, and the Second National Commission on Stratigraphy of China formally suggested establishing the corresponding chronostratigraphic unit, the Tunggurian Stage, based on the Tunggurian Age in 1999. The name of this stage comes from a lithostratigraphic unit, the Tunggur Formation, and the stratotype section is located at the Tunggur tableland, 15 km southeast of Saihan Gobi Township, Sonid Left Banner, Inner Mongolia. The Tunggurian Age is correlated to the Astaracian of the European land mammal ages, and they share the same definition of the lower boundary at the base of the paleomagnetic Chron C5Bn.1r with an age of 15.0 Ma. In the Tairum Nor section on the southeastern edge of the Tunggur tableland, this boundary is situated within the successive deposits of reddish‐brown massive mudstone of the lower part of the Tunggur Formation, with a distance of 7.6 m from the base of the grayish‐white sandstones in the middle part of the section. The Tunggurian is approximately correlated to the upper part of the marine Langhian and the marine Serravallian in the International Stratigraphical Chart. The Tunggurian Stage includes two Neogene mammal faunal units, i.e. NMU 6 (MN 6) and NMU 7 (MN 7/8). The Tairum Nor fauna from the Tairum Nor section corresponds to NMU 6, and the Tunggur fauna (senso stricto) from the localities on the northwestern edge of the Tunggur tableland, such as Platybelodon Quarry, Wolf Camp and Moergen, corresponds to NMU 7. Among the Middle Miocene mammalian faunas in China, the Laogou fauna from the Linxia Basin, Gansu, the Quantougou fauna from the Lanzhou Basin, Gansu, the Halamagai fauna from the northern Junggar Basin, Xinjiang, and the Dingjiaergou fauna from Tongxin, Ningxia correspond to NMU 6.

Magnetostratigraphic dating of mammalian fossils in Junggar Basin, northwest China

The first detailed chronology for the late Oligocene to early Miocene continental record in northern Junggar Basin is presented, based on rock magnetic experiments and magnetostratigraphic investigations of a 192 m thick mammal-bearing section in the Ulungur River area. Magnetites and hematites were identified as the main carriers for the characteristic remanent magnetization, and the resulting polarity sequence allows an unambiguous correlation to the geomagnetic polarity time scale (GPTS). Furthermore, the Tieersihabahe fauna layer occurs below the Paleocene/Neocene boundary, and the Suosuoquan fauna layer is just above the Neocene onset. Therefore, the age of the Tieersihabahe fauna and Suosuoquan fauna layers can be definitely estimated to be about 25.2 Ma and 22.5 Ma, respectively.

Chapter 21

A mid-Tertiary rock sequence at the Tieersihabahe locality from the Ulungur River area in the northern Junggar Basin, Xinjiang Province, China, is described. The study introduces three late Oligocene/Early Miocene faunas from the continuous section of the “Ulunguhe” and Suosuoquan formations within the sequence, and discusses the age determination, faunal correlation, and existing problems concerning the formations and faunas. The “Ulunguhe” fauna at the Tieersihabahe locality is late Oligocene in age, correlative to the Taben Buluk fauna. The 99005 fauna is probably Oligocene–Miocene transitional. The Suosuoquan fauna is regarded as early Miocene, so the Oligocene/Miocene boundary would be contained in the continuous section at the Tieersihabahe section.