Paleoecology of Late Carboniferous Phylloid Algae in Southern Guizhou,SW China

Phylloid algae arc important rcef-builders in the late Carboniferous. This paper focuses on the paleoecology of phylloid algae in the Late Carboniferous on well-exposed reefs in Ziyun County, Guizhou Province. Phylloid algae growing closely packed arc attached via holdfast or similar structure to substrate. They were growing in environments such as shallow water, photic zone and below the wave base with medium energy currents. They have a variety of morphological forms, such as single cup-shaped, cabbage-shaped and clustering cup-shaped. The thalli arc of certain tenacity and intensity. In the areas dominated by phylloid algae, other marine orgam＇sms arc relatively scarce. Obviously, phylloid algae arc stronger competitors for living space than other co-occurring organisms.

Petrogenesis of Early and Late Carboniferous Volcanic Rocks in the Yining Block:Constraints from Sr-Nd Isotope

The Yining Block is located in the southwestern part of the Central Asian Orogenic Belt （CAOB）,which is characterized by widespread Carboniferous volcanic rocks.Recently,we carried out the National Nature Science Foundation of China （No.41273033） and Special Fund for Basic Scientific Research of Central Colleges （No.310827153407） project,and focused on two suits volcanic rocks from the Early Carboniferous Dahalajunshan Formation and the Late Carboniferous Yishijilike Formation.Field observations,zircon U-Pb dating,and Sr-Nd isotopic dating were conducted to evaluate the petrogenesis.

Middle and Late Carboniferous Tetracoral Assemblages and Biogeography of China

China is rich in Middle and Carboniferous fossil corals. The coral faunas in different regions have varying characteristics and can be divided into distinct assemblages. The coral fauna in South China is dominated by the order Caninida and contains numerous endemic elements; that in North China has a lot of Middle Carboniferous corals which are monotonous in species, with Late Carboniferous solitary corals being predominant. The coral fauna in Junggar mainly contains large bi-zoned solitary caninids, while that in southern Khingan is similar to that in South China due to the presence of abundant tri-zoned compound corals. In northern Tibet the coral fauna is also similar to that in South China, but in southern Tibet it is of a cold-water type. Therefore, the Middle and Late Carboniferous coral geography of China can be divided into the Tethys, Boreal and Gondwana Realms.

Paleomagnetic results from Late Carboniferous to Early Permian rocks in the northern Qiangtang terrane, Tibet, China, and their tectonic implications

Results of a systematic paleomagnetic study are reported based on Late Carboniferous to Early Permian sedimentary rocks on the north slope of the Tanggula Mountains, in the northern Qiangtang terrane （NQT）, Tibet, China. Data revealed that magnetic minerals in limestone samples from the Zarigen Formation （CP^z）are primarily composed of magnetite, while those in sandstone samples from the Nuoribagaribao Formation （Pnr） are dominated by hematite alone, or hematite and magnetite in combination. Progressive thermal, or alternating field, demagnetization allowed us to isolate a stable high temperature component （HTC） in 127 specimens from 16 sites which successfully passed the conglomerate test, consistent with primary remnance. The tilt-corrected mean direction for Late Carboniferous to Early Permian rocks in the northern Qiangtang terrane is D°=30.2°, Is=-40.9°, ks=269.0, a95=2.3°, N=16, which yields a corresponding paleomagnetic pole at 25.7°N, 241.5°E （alp/rim=2.8°/1.7°）, and a paleolatitude of 23.4°S. Our results, together with previously reported paleomagnetic data, indicate that： （1） the NQT in Tibet, China, was located at a low latitude in the southern hemisphere, and may have belonged to the northern margin of Gondwana during the Late Carboniferous to Early Permian; （2） the Paleo-Tethys Ocean was large during the Late Carboniferous to Early Permian, and （3） the NQT subsequently moved rapidly northwards, perhaps related to the fact that the Paleo-Tethys Ocean was rapidly contracting from the Late Permian to Late Triassic while the Bangong Lake-Nujiang Ocean, the northern branch of the Neo-Tethys Ocean, expanded rapidly during this time.

Re-Os Dating of the Suoerkuduke Cu (Mo) Deposit,Fuyun County,Xinjiang,and Its Geodynamic Implications

The Suoerkuduke Cu （Mo） deposit, in the same metallogenic belt with Xilekuduke Cu-Mo deposit, is located in the Armantai island arc belt on the northern margin of East Junggar, Northwest China. Rhenium and osmium isotopic analysis of seven molybdenite samples from the deposit was used to determine the age of mineralization. A seven-point isochron age of 317.7±7.6 Ma, which is consistent, within analytical error, with the average model age of 323.3±1.9 Ma indicates that this deposit was formed at transitional period between the Early and Late Carboniferous. This age is obviously later than that of the Lower Devonian Tuoranggekuduke Formation acting as the wall rock but contemporaneous with the early stage of plutonism （330-268 Ma） in East Junggar. Based on the characteristics of mineralization age and tectonic setting of many typical deposits on the northern margin of East Junggar, we proposed that the mineralization age of Suoerkuduke deposit is a key period of East Junggar for the tectonic regime transforming from compression to extension and also the time when granitoids and deposits widely spread in this area. Mineralization and formation of skarn in this deposit are closely related to felsic-intermediate magmatism. The distinct characteristic from typical skarn-type deposits is that the metallogenic parent intrusion is a huge batholith in the depth. The Cu （Mo） mineralization, moyitc, and granite porphyry are all derived products of the batholith.