华南泥盆纪层孔虫生长形态及其环境意义  

Growth Forms of Devonian Stromatoporoids and Their Environmental Significance in South China

作　　者：吴义布[1,2] 龚一鸣[1] 

机构地区：[1]中国地质大学生物地质与环境地质国家重点实验室,武汉430074 [2]甘肃省地质调查院,兰州730000

出　　处：《地质学报》2013年第6期887-904,共18页Acta Geologica Sinica

基　　金：国家重点基础研究计划"973"项目(编号2011CB808800);国家自然科学基金项目(编号41072252)共同资助的成果

摘　　要：通过对四川甘溪、贵州独山、广西六景和桂林神湾等泥盆纪剖面中层孔虫"生长形态"的系统研究,识别出层孔虫内部存在2大类7小类年生长条带:密度条带(疏密型、递变型、混杂型、突变型和"生长脊"型)和结构条带(结构差异型、单一结构层式),并发现层孔虫年生长条带广泛发育,在中泥盆世30属203种中均有记录。在层孔虫内部识别出了6类生长间断:含沉积物型、综合型、深色型、突变型、边部型和结构差异型。据此,系统总结了华南泥盆纪层孔虫生长形态及其相带分布规律,发现华南泥盆纪层孔虫主要分布在局限台地、开阔台地和台缘礁等7个相带中,各相带层孔虫生长形态差异明显。同时,发现和总结了与礁单元稳定构建密切相关的5个生长形态参数:总体形态、V/B(高与底宽之比)、基面、生长速率和生长间断。研究表明:层孔虫生长过程多由连续生长和间断二者共同组成,受到周期性环境因素(如冷、暖)和随机环境因素(如沉积速率变化)的共同影响,并以后者为主;提出并验证了层孔虫生长形态是高分辨率沉积环境变化的示踪指标,如利用年生长条带计算沉积速率;同时提出层孔虫生长形态是精细分析珊瑚-层孔虫礁的重要手段,如利用层孔虫生长速率推算礁生长速率等。In this paper , growth forms and related parameters of stromatoporoids from four Devonian sections （ Ganxi of Sichuan , Dushan of Guizhou , Shenwan and Liujing of Guangxi ） were measured and collected in South China. Three aspects of progresses have been made as follows ： ① Two kinds of density and texture bands in an annual growth band were recognized in vertical thin sections of stromatoporoids from the studied sections.They can be subdivided into seven subgroups ： dark-light type ,＂ gradual change ＂ type ,＂ abrupt change ＂ type ,＂ gradual-abrupt change ＂ type ,＂ growth ridge ＂ type ,＂ different structure ＂ type and ＂ single structure ＂ type.And annual growth bands in stromatoporoids were widely developed in different taxa including 30genera and 203species in the Middle Devonian in China , and in spatiotemporal distributions.② Six types of growth interruptions were recognized in thin slices of stromatoporoids , including ＂ sediment inclution ＂ interrruption , commix interruption , dark growth interruption , abrupt interruption , marginal interruption.Different stromatoporoid growth forms distributed in 7 facies in South China , and 5useful growth parameters to study reef units were summarized ： holistic shape , V / B , initial surface , growth rate and growth interruption.Growth forms of stromatoporoids were controlled by both periodic and episodic environmental parameters , with the former being more important.Our studies showed that the stromatoporoid was a good carrier to reconstruct palaeoenvironments and reef unit growth histories.

关 键 词：泥盆纪 层孔虫 生长形态 礁相 古环境 华南 

分 类 号：P52[天文地球—古生物学与地层学]