Latest Zircon U-Pb Geochronology of the Huoshiling Formation Volcanic Rocks in the Southeastern Margin of the Songliao Basin

Objective The Huoshiling Formation is the earliest volcanic stratum in the Songliao Basin,composed mainly of intermediate-basic volcanic rocks,with rare fossils.The geological age of this formation has been controversial for long.

New Progress of Oil and Gas Research in the Tonghua Area, East of the Songliao Basin

The Tonghua region in the east of the Songliao Basin is a high-risk and blank area of petroleum exploration. The unrevealed key problems including the growth of source rocks, hydrocarbon generation potential and oil and gas source and the low exploration degree have constrained the further study of petroleum geological conditions and exploration deployment. Based on outcrop and core observations, geological section survey, trench exploration, high-precision gravity and magnetism and geological survey wells, this work discussed the basic geological conditions, main hydrocarbon source rocks, hydrocarbon generation potential and the oil and gas source.

Petrologic characteristics and genesis of dolostone from the Campanian of the SK-I Well Core in the Songliao Basin,China

The well SK-I in the Songliao Basin is the first scientific borehole targeting the continental Cretaceous strata in China. Oval concretions, thin laminae and beds of dolostone are found intercalated within mudstone and organic-rich black shale in the Nenjiang Formation of Campanian age. Low ordered ferruginous dolomite is composed of euhedral--subhedral rhombs with cloudy nucleus and light rims formed during the diagenesis, which are typical features of replacement. The heavy carbon isotopes （δ13CPDB -- 1.16-16.0） are results of both the fermentation of organic matter by microbes and degassing of carbon dioxide during the period of diagenesis, and the presence of light oxygen isotopes （δ18OPDB- 18.53--5.1） is a characteristic feature of fresh water influence which means the carbonate may have been altered by ground water or rainwater in the late diagenesis. Marine water incursions into the nor- mally lacustrine basin have been proved by both the salinity of Z value and the occurrence of foraminifera in the same strata where dolomite occurs. Pyrite framboids observed by SEM are usually enclosed in the dolomite crystals or in the mudstones, supporting the sulfate reducing bacteria （SRB）. The formation of both dolomite and pyrite are associated with marine water incursions, which not only supply magnesium ion for dolomite, but also result in limited carbonate precipitation in the basin. The presence of pyrite framboids indicates the development of an anoxic environment associated with salinity stratification in the lake. The dolomite in the Nenjiang Formation is the results of marine water incursions, diagenetic replacement of calcareous carbonate and sulfate reducing bacteria （SRB）.

Identification Marks of Cretaceous Shallow-Water Delta in the Songliao Basin,China

Shallow-water deltas are now a research focus of international sedimentology. Researchers have recently discovered that water depth is an important controlling factor for the development of shallow deltas, and that significant differences exist between shallow-water deltas and the traditional Gilbert deltas. The identification marks of shallow-water deltas are critical for better understanding sedimentary characteristics of these deltas. In continental basins, especially China＇s Mesozoic and Cenozoic continental basins, shallow-water deltas are widely developed. Thus, this work took the Songliao Basin as an example to analysis this kind of deltas.

Stratal Slice Recognition of Thin Shallow-Water Delta Sandbodies in the Songliao Basin

Objective China＇s petroleum exploration has entered a new stage of finding deeply buried thin sandbodies lbr the abundant oil resources they contain. Here thin sandbodies refer to those less than 10 m in thickness, or even less than 1-2 m. It is difficult to depict thin-layer sandbodies of different genetic types using conventional core, well logging and seismic data due to their limited vertical resolution in petroliferous basins. However, seismic sedimentology provides a new research method especially tbr thin sandbody interpretation, i.e., validating interpreted sedimentary sandbodies from 3D seismic data based on horizontal resolution, stratal slice and seismic geomorphology interpretation. At present, a series of studies on seismic sedimentology in North America marine basins and elsewhere have been completed successfully and are relevant to the exploration and development of oil and gas fields.