Stratigraphic and micropaleontological constraints on the middle Eocene age of the mammal-bearing Kuldana Formation of Pakistan
Stratigraphic and micropaleontological constraints on the middle Eocene age of the mammal-bearing Kuldana Formation of Pakistan
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DOI：
10.1671/2409
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发表时间：
2003-09-12
影响因子：
1.4
通讯作者：
Gingerich, PD
中科院分区：
文献类型：
--
作者：
Gingerich, PD
巴基斯坦的库尔达纳组以其化石哺乳动物而闻名，包括原始的鲸类动物，如Pakicetus及其近亲。在不同的研究中，库尔达纳哺乳动物的年龄被认为是卢泰阶早期（中始新世早期）、伊普尔阶晚期（早始新世晚期），或者最近，跨越伊普尔阶的大部分时间到卢泰阶早期（早始新世早期到中始新世早期）。Kuldana组是一个相对较薄的20 - 120米厚的大陆红层的低海台舌，位于一个厚得多的有孔虫丰富的海相地层序列中。浮游有孔虫和浅层底栖有孔虫将Kuldana组的时代限制在早始新世晚期或中始新世早期，目前全球海平面地层学的解释倾向于后者。在发现库尔达纳哺乳动物的低海林间隔期很短，这意味着迄今为止回收的样本之间的差异可能代表当地生活环境、沉积地点和采样的差异，而不是年龄上的任何实质性差异。这加强了一个解释，首先提出的角度，同时代的Kalakot哺乳动物恢复在印度的Subathu组。
The Kuldana Formation of Pakistan is best known for its fossil mammals, including primitive cetaceans such as Pakicetus and its close relatives. Kuldana mammals have been regarded in different studies as early Lutetian in age (early middle Eocene), late Ypresian (late early Eocene), or, recently, to span much of Ypresian through early Lutetian time (early part of the early Eocene through the early middle Eocene). The Kuldana Formation is a relatively thin, 20-120 m thick low-sea-stand tongue of continental red beds lying within a much thicker sequence of foraminiferarich marine formations. Planktonic and shallow benthic forams constrain the age of the Kuldana Formation to the late early Eocene or the early middle Eocene, and current interpretation of global sea level stratigraphy favors the latter. The short duration of the low-sea-stand interval when Kuldana mammals are found means that differences between samples recovered to date probably represent differences in local living environments, sites of deposition, and sampling, rather than any substantial difference in age. This reinforces an interpretation first proposed from the perspective of coeval Kalakot mammals recovered from the Subathu Formation in India.