Late Paleozoic reefs and their significance for tectonics and oil-gas exploration in the Hinggan-Inner Mongolia area

Abstract

Many reefs of the Late Paleozoic have been discovered recently in the Hinggan-Inner Mongolia area. These reefs clearly are geographically extensive, and possess distinctive features and well-developed reef-facies. They have been found to contain five reef-building communities and were constructed in four periods. Colonial coral-algal reefs at Aohan and Chifeng represent a warm shallow-sea in the Carboniferous. Different reefs in the Xiwu Banner were formed in three periods: early Late Carboniferous, late Late Carboniferous and Early Permian. These reefs were built in warm sea conditions. Their buildup types include colonial coral frameworks, algae-buildings and lime-mud mounds. Bryozoan reefs in the Zhalaite and Dongwu banners were built in the late Middle Permian and thrived in a cold shallow-sea. All reefs grew independently on two kinds of sedimentary platforms, carbonate and carbonate-clastic mixed platforms. Four reef-forming periods occurred later from south to north, along a collisional course between the North China Plate and the Siberian Plate. These reefs can be arranged into three 'reef-links' or reef zones that extend along plate margins. Among these, the Aohan-Chifeng reef-link indicates a northern margin of the North China Plate, the Zhalaite-Dongwu reef-link marks a southern margin of the Siberian Plate, and the Xiwu-Beishan reef-link reflects the former existence of some inter-plates. The strata of each reef-facies are thick and contain rich asphalt deposits. Overlapping and heteropic layers are very thick and contain dark oil/gas-rich horizons; TOC analyses verify that most of these are good hydrocarbon source rocks. This study shows that the study area is an excellent candidate for oil-gas exploration. reefs, Late Paleozoic, Hinggan-Inner Mongolia fold-zone, oil-gas exploration Citation:Tian S G, Zhang Y S, Wang J T, et al. Late Paleozoic reefs and their significance for tectonics and oil-gas exploration in the Hinggan-Inner Mongolia area.

New Early Permian Paleomagnetic and Geochronological Data From the Xilinhot–Songliao Block and Their Implications for the Relationship Between the Paleo‐Asian Ocean and the Paleo‐Tethys Ocean

“…The bryozoon and coral reefs is modified from Tian et al. (2011). (b) New division of the tectonic domains.…”

“…The bryozoon and coral reefs are modified from Tian et al. (2011). (b, c) Geological map and (d) stratigraphic sequence in the Xilinhot and Shuangsheng sections in the eastern Xilinhot‐Songliao Block (XSB; modified from BGMRIM, 1991).…”

Morphometrics and paleoecology ofCatenipora(Tabulata) from the Xiazhen Formation (Upper Ordovician), Zhuzhai, South China

“…Catenipora was previously reported to be the dominant reef-former in the Xiazhen Formation, with nearly 50% of the reef frameworks composed of in situ coralla (Bian et al, 1996; Li et al, 2004). In the present study, however, it was found that the majority of Catenipora coralla throughout the formation are significantly fragmented and not preserved in growth position (Table 9).…”

“…1.1, 1.2) (Chen et al, 1987; Rong and Chen, 1987; Wu, 2003; Zhang et al, 2007; Zhan and Jin, 2007; Rong et al, 2010). Numerous Upper Ordovician reef complexes were previously described from the shallow platform lagoon to marginal reef deposits of the Sanqushan Formation and its landward equivalent, the Xiazhen Formation (Yu et al, 1992; Bian et al, 1996; Webby, 2002; Li et al, 2004). The shallow platform carbonates of the Sanqushan and Xiazhen formations grade into contemporaneous fine-grained clastics of the Changwu Formation on the distal Zhe-Gan Platform toward the Zhe-Wan Basin (Chen et al, 1987; Li et al, 2004).…”

Environmental and tectonic significance of Late Permian reefs in the Linxi and adjacent areas in Inner Mongolia of China

“…Many bryozoan-built reefs have been reported in cold-water areas of the Carboniferous-Permian of North America, Germany, Siberia, and Inner Mongolia of China (Heckel, 1989;Tian et al, 2011). Bryozoan fossils are good markers for indicating facies, owing to their sensitivity to conditional factors.…”