Dasycladalean algae and their depositional environments in the Sylhet Limestone Formation (lower-middle Eocene), Bengal Basin
Dasycladalean algae and their depositional environments in the Sylhet Limestone Formation (lower-middle Eocene), Bengal Basin
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DOI：
10.1007/s12594-010-0078-9
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发表时间：
2010-07
影响因子：
1.3
通讯作者：
S. Humane;Savita N. Chaurpagar;Samaya S. Humane;P. Kundal
中科院分区：
文献类型：
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作者：
S. Humane;Savita N. Chaurpagar;Samaya S. Humane;P. Kundal
首次在印度孟加拉盆地始新世中下统锡耶特灰岩组中发现了丰富多样的粗枝藻组合。本文通过对锡耶特灰岩组中毛枝藻科3科11种（Cymopolia inflataramosaSegonzac，C. mayaeneseJohnson和Kaska，C. paronaiRaineri，Cymopoliasp.），三孔菌科（Dissocladella lunataSegonzac，Dissocladellasp.，Jodotella sloveniaensisDeloffre和Radoicic）和髋臼科（Clypeina socanensisDeloffre和Radoicic，Clypeinasp.，Terquemellasp.，Neomerissp.）。下始新统锡耶特灰岩组以毛枝藻为主，含盐藻和黑藻，珊瑚藻较少。这表明它们在温暖的沃茨中5-6 m深处的开阔泻湖到陆架环境中生长茂盛。中始新世锡耶特石灰岩组中的粗枝藻类种属逐渐减少。与孢子石相关的珊瑚藻的优势表明，中始新世锡耶特石灰岩组的石灰岩沉积于温暖热带沃茨中约40-60 m深处的沿岸的至浅水高能开阔陆棚海洋环境。
A very rich and diversified dasycladalean algal assemblage has been discovered from the Sylhet Limestone Formation (lower-middle Eocene) of the Bengal Basin of India for the first time. The depositional environments of the Sylhet Limestone Formation have been discussed based on the presence of the 11 species of the dasycladalean algae belonging to the three families Dasycladaceae (Cymopolia inflataramosaSegonzac,C. mayaeneseJohnson and Kaska,C. paronaiRaineri,Cymopoliasp.), Triploporaceae (Dissocladella lunataSegonzac,Dissocladellasp.,Jodotella sloveniaensisDeloffre and Radoicic) and Acetabulariaceae (Clypeina socanensisDeloffre and Radoicic,Clypeinasp.,Terquemellasp.,Neomerissp.). The lower Eocene Sylhet Limestone Formation revealed predominance of dasycladalean algal assemblage with the halimedacean and udoteacean algae and rare occurrence of coralline algae. This suggests their luxuriant growth in the open lagoonal to shelf environment at the depth of 5–6 m in the warm waters. There is a gradual decrease in the dasycladalean species and genera in the middle Eocene Sylhet Limestone Formation. The predominance of coralline algae associated with theSporolithonindicates that the limestone of middle Eocene Sylhet Limestone Formation have been deposited at the littoral to shallow, high energy open shelf marine environments at a depth of about 40–60 m in warm tropical waters.