【研究目的】 粤西北连州地区在早石炭世发育了大套的碳酸盐岩，代表性地层连县组是研究该时期碳酸盐岩沉积的理想地层。原连县组的半岭村选层型剖面底界不清，露头破坏严重，已失去层型剖面的功能价值，亟须在连县组中寻找新的层型剖面，为该地区下石炭统的层序地层学研究和区域地质调查研究提供参考。【研究方法】 通过大比例尺剖面测制、岩石鉴定和古生物地层等手段，系统研究了连州市九陂镇龙潭石街头地层剖面的岩性组合、生物化石和沉积环境，获得了其层序地层学特征，并厘定其底界时代。【研究结果】 依据有孔虫的演化序列，以有孔虫化石Quasiendothyra kobeitusana，Q.konensis的消失和Bisphaera irregularis birina的首次出现，揭露了粤西北连州地区泥盆系与石炭系的界线从长垑组顶部层位粒屑灰岩中间通过，结合地层的叠复关系，连县组的发育时代可下延限于早石炭世杜内期。【结论】 该剖面是目前区内已知早石炭世早期碳酸盐岩连续沉积厚度最大的剖面，地层序列发育完整，顶、底界面清楚，是连县组中已发现的最为理想的辅助层型剖面。这为建立连县组的次层型（参考剖面）奠定了基础。上述成果，对于粤西北地区区域地层格架的构建，区域地层划分与对比研究的进行，以及区域地质背景的完善都具有较大意义。
This paper is the result of geological survey engineering.
[Objective] A large suite of carbonates developed in the Early Carboniferous in the Lianzhou area of northwest Guangdong, and the representative stratigraphic section of the Lianxian Formation is an ideal stratigraphic section for studying carbonate deposition in this period. The bottom boundary of the selected stratigraphic section of the Banling Village of the former Lianxian Formation is unclear and the outcrop is severely damaged, which has lost the functional value of the stratigraphic section. There is an urgent need to find a new stratigraphic section in the Lianxian Formation to provide a reference for the stratigraphic stratigraphy of the Lower Carboniferous and regional geological survey studies in the area.
[Methods] Tematically studied by means of large scale sectioning, rock identification and paleostratigraphy of the stratigraphic section in Longtan Shijietou village of Jiubei, Lianzhou city, Guangdong. The stratigraphic characteristics of the sequence were obtained and the age of the bottom boundary was determined.
[Results] Based on the evolutionary sequence of foraminifera, the disappearance of foraminiferal Quasiendothyra kobeitusana, Q. konensis and the first occurrence of Bisphaera irregularis birina reveal that the boundary between Devonian and Carboniferous in the Lianzhou area of northwestern Guangdong passed through the middle of the granular tuff at the top of the Changlai Formation. Combined with the stratigraphic, the developmental age of the Lianxian Formation can be the restricted to the Early Carboniferous Dunei stage.
[Conclusions] This section is the largest section with continuous deposition of Early Carboniferous early carbonate rocks known in the region, with complete stratigraphic sequence development and clear top and bottom interfaces, and is the most ideal secondary stratigraphic section found in the Lianxian Formation. This lays the foundation for the establishment of the substratigraphic type (reference section) of the Lianxian Formation. The above results are of great significance for the construction of the regional stratigraphic framework in northwestern Guangdong, the conduct of regional stratigraphic delineation and comparative studies, and the improvement of the regional geological background.
刘子宁,窦磊,张伟,朱文斌,莫滨,陈恩,贾磊. 粤西北连州地区下石炭统连县组新剖面的确定与特征[J]. 中国地质, 2023, 50(2): 533-542.
LIU Zining, DOU Lei, ZHANG Wei, ZHU Wenbin, MO Bin, CHEN En, JIA Lei. Identification and characteristics of a new section of the Lower Carboniferous Lianxian Formation in the Lianzhou area, northwest Guangdong[J]. Geology in China, 2023, 50(2): 533-542(in Chinese with English abstract).