摘要
本文系统地讨论了黑龙江双鸭山、集贤两煤田的中生代含煤地层序列,综合各门类化石研究结果,认为海相的绥滨组和东荣组属晚侏罗世卡洛夫晚期至伏尔加期,非海相的城子河组和穆棱组属早白垩世尼坎期。文内提供11条详细的钻探剖面的生物地层资料。
The upper Jurassic and Lower Cretaceous coal-bearing measures were developed in the south area of the Heilongjiang (Amur) River, but are now buried in depths of several hundred meters underground. The present materials are mainly obtained from the bores in two mining coalfields, namely Shuangyashan and Jixian, in eastern Heilongjiang, Northeast China. The stratigraphical sequence was preliminarily reported by Huang (1989) and is now recognized as (1) Suibin Formation; (2) Dongrong Formation; (3) Chengzihe Formation and (4) Muling Formation in ascending order, which are separately described as follows:
1. Suibin Formation
As the lowest horizon of the Mesozoic strata in this area, the formation is grouped by grey sandstones, with a maximum thickness of about 263m, unconformably overlying the Palaeozoic substrata. This formation is restricted to the area between the Heilongjiang and Songhuajiang Rivers in geographical distribution, and might have been formed in the early stage of the regional transgression. Only a few marine fossil bivalves were found from its upper and middle parts, which are identified as Filosina subovalis J. Chert et Gu, Palaeonucula makitoensis Hayami, Nuculana aff. roederi (Loriol) and Lopha? sp. Based on faunal aspects this formation is regarded as belonging to Late Jurassic in age but it is difficult to make a further determination at stage level. However, in our consideration, this formation is not older than Late Callovian because the deposits are correspondingly limited and continuously overlain by the upper Oxfordian-lower Kimmeridgian Dongrong Formation.
2. Dongrong Formation
This formation has a wider distribution than the Suibin Formation, extending from the Heilongjiang River southwards to the Dongrong county, with a maximum thickness of about 395m. It may be divided into two parts, with the lower part consisting of dark grey and black sihstones intercalated with some tuffbeds, and the upper part grouped by grey and dark-green fine-grained sandstones intercalated with tufts. Its base conformably overlies the Suibin Formation. Abundant marine fossils have been found, including bivalves, ammonites, dinoflagellates, etc., indicating a re gional transgression. Within the faunas four buchiid bivalve zones and two dinoflagellate assemblages have been recognized as shown in the following table:
This biostratigraphical sequence may be helpful for correlating the Upper Jurassic of eastern Heilongjiang with the boreal standards.
3. Chengzihe Formation
The name of this formation is derived from the nomenclature for the coal series in the Jixi Basin, which is located south of the present area. However, both may not be equivalent to each other, because the latter contains Kimmeridgian buchiids in its lower part but the former bears Lower Neocomian or Berriasian bivalves (Tetoria cf. yokoyamai and Protocyprina naumanni) in its lower part. This formation widely distributed in the two coalfields is represented by clastic coal-bearing meatures with a thickness of 350—1290m and is grouped by sandstones, siltsones, mudstones and turfs. In this formation there exist about 60 coal beds, including 18 industrial ones. A regional sedimentary discontinuity is present between the Chengzihe Formation and the underlying Dongrong Formation. Usually, sedimentary cycles are clearly shown in this formation, and based on the development of sedimentary cycles the formation can be further divided into the first, second, third and fourth members in ascending order; all of them yield rich macroplants and spore-pollen, while the first two members contain some molluscs. Since analyses of the floras (including macrofloras and microfloras), from this formation show that the evolutionary rate was not high from its lower to upper parts, they are referred to the single assemblage (for details see Cao Zheng-yao and Li Wen-ben's articles in this volume). However, the age of the macroplant assemblage is considered as belonging to Lower Neocomian by Cao, while that of the microplant to Hauterivian-Barremian by Li. The bivale (Tetoria cf. yokoyamai - Protocyprina naumanni assemblage) from the lower part of Member 2 is a brackish water fauna, which was reported from the Kuwagima fauna in the Inner zone and the Ryoseki fauna in the Outer zone of Japan, and was dated Berriasian or Lower Neocomian by Japanese geologists in combination with ammonite evidence.
4. Muling Formation
This formation was also named from that of the Jixi basin, with a distribution over the present coalfields, and consisting of 480—1 000m thick dark grey and dark green siltstones and black mudstones intercated with turfs and coal seams. It is in conformable connexion with the Chengzihe Formation. In lithological character, it differs from the latter in having fewer coal beds, in which the plants and spore-pollen indicate a Neocomian age.
出处
《古生物学报》
CAS
CSCD
北大核心
1992年第2期129-162,257,共34页
Acta Palaeontologica Sinica
关键词
中生代含煤层
古生物学
黑龙江
eastern Heilongjiang, Mesozoic coal-bearing measures, Upper Jurassic—Lower Cretaceous.
