Introduction to special section: Mapping mixed clastic and carbonate depositional systems in lacustrine basinsAuthors:
Mixed siliciclastic-carbonate sediments (MSCSs) are quite common in modern and ancient basins. They reﬂect the combined effects of facies dynamics, climate, changes in relative sea or lake level, and varying sediment supply rates, which is why their understanding is important in both paleoecologic and paleoenvironmental studies. The classiﬁcation, controlling factors, and genetic environments of MSCSs were ﬁrst studied and discussed in the 1980s. In the following decades, emphasis of many studies was on understanding the genetic mechanisms of MSCSs; many genetic models were put forward with many challenging issues. There have been significant new developments in recent years in understanding the mixed clastic and carbonate depositional systems in lacustrine basins, especially concerning the diagenesis characteristics, sedimentary structures, origin and distribution, and the relationship between MSCSs and hydrocarbon resources. This special section brings together diverse yet related works to address the functioning of MSCSs characteristics in different lacustrine basins. The overall objective of this section is to showcase and synthesize petroleum geology and to explore the complex behaviors and mechanisms of MSCSs systems in different basins, including the Bohai Bay Basin, Subei Basin, and Pearl River Mouth Basin. This special section includes four system-focused papers. Mixed clastic and carbonate depositional system examples cover a wide range of spatial and temporal scales and provide a series of new understandings in hydrocarbon exploration. As a result, the MSCSs characteristics and mechanisms of mixed clastic and carbonate depositional systems in lacustrine basins are showcased.
Wei Li et al. describe the original characteristics of mixed clastic and carbonate sediments of the Paleogene Funing Formation in the Subei Basin, eastern China. Both the interstratified siliciclastic-carbonate sediments and diverse mixed sedimentary rocks can be clearly identified.
Zhang et al. explore the lithological potential of mixed siliciclastic-carbonate rocks and try to provide a new perspective for hydrocarbon exploration in the Pearl River Mouth Basin. The study is focused on lithologic traps in future exploration due to the lack of new structural traps.
Sen Li et al. investigate different scales of cyclical sedimentation and dolomitization associated with mixed siliciclastic-carbonate sediments in Eocene strata of Huanghekou sag, Bohai Bay Basin. Reservoir physical properties are closely related to this cyclicity, and grain-supported framework of carbonate-dominated lithofacies allows preservation of intergranular pores.
Xu et al. describe four kinds of relationships between sediment-source supply and mixed deposition of siliciclastic and carbonate in Paleogene, Bohai Sea area, China. The different relationships lead to distinct characteristics of mixed siliciclastic-carbonate sediments.