Abstract

The palynoflora and organic petrography of core samples from the Tyler Formation in the Williston Basin, North Dakota, USA were evaluated to determine their age and depositional environment. The palynofloras are assigned to seven plant groups used by previous authors who studied Carboniferous floras. Lycopsid trees, represented by Lycospora species and Crassispora kosankei are the most abundant and well-preserved miospores recorded. Palynomorphs representing small lycopsids, calamites, cordaites, and conifers, comprise a relatively minor part of the palynoflora. The petrographic component from seven coeval coal samples contain moderate to high mineral content and macerals which are dominated by vitrinite (woody components) and to a lesser extent inertinite and liptinite (lipid-rich plant material). Common vitrinite macerals include collotelinite and collodetrinite, and semifusinite and minor fusinite representing inertinite macerals. The palynofloras are of Early Pennsylvanian age, based on the presence of the age-significant fossils Schulzospora rara and Cirratriradites saturnii together with abundant Lycospora spp. The palynoflora and petrographic data suggest that the Tyler Formation in this location was deposited in a fluvially-dominated delta with some tidal influence. Wet, stagnant anoxic environments (coal swamps) were frequently flooded with clastic material from a fluvial source. Macerals, especially inertinite, imply periods of subaerial exposure, fire, or highly oxygenated waters, and liptinite (lipid-rich plant material), suggests periodic drowning of the coal swamp and formation of shallow lacustrine paleoenvironments.

摘要

对美国北达科他州威利斯顿盆地泰勒组岩心样品的古生物和有机岩相进行了评估，以确定它们的年龄和沉积环境。将古菌群分配给研究石炭纪植物群的先前作者使用的七个植物群。Lycopsid树为代表Lycospora物种和Crassispora kosankei是记录最丰富和保存最完好的微孔。代表小型番茄红素，方沸石，堇青石和针叶树的贪食虫只占食草植物的一小部分。来自七个中古时期煤样品的岩石学成分包含中等至高的矿物质含量和矿物成分，这些成分以镜质体（木质成分）为主，而较少的是惰质岩和锂质变质岩（富含脂质的植物材料）。常见的镜质软组织包括软钙石和软水铝石，以及代表惰质软组织的半褐铁矿和次要辉石岩。由于存在具有重要年龄的化石Schulzospora rara和Cirratriradites saturnii以及大量的Lycospora，因此古植物花粉草是宾夕法尼亚州早期的植物。spp。古生物和岩相学数据表明，该位置的泰勒组沉积在一个潮汐影响的河流主导的三角洲。潮湿，停滞的缺氧环境（沼泽）经常被河流来源的碎屑充斥。黄石类，特别是惰质，暗示着暴露在地下的空气，火或高含氧量的水以及脂蛋白（富含脂质的植物材料）的时期，暗示着煤沼泽的周期性淹没和浅湖相古环境的形成。