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Timing and cause of the disappearance of some elongated taxa in the Indian Ocean: Study from NGHP Hole 17A
Journal of Earth System Science ( IF 1.3 ) Pub Date : 2020-06-03 , DOI: 10.1007/s12040-020-01399-9
Sanjib Biswas , Ajoy K Bhaumik

Disappearance of many elongated benthic foraminifera across the Mid-Pleistocene Transition (MPT) is popularly known as ‘Stilostomella extinction’. This event is reported from several sites across the world and it is believed that most of the elongated benthic families disappeared within 0.76–0.5 Ma. It is assumed that the presence of cold bottom water triggered their disappearance. The present study is pursued on sediment cores collected from National Gas Hydrate Program Hole 17A, Andaman Sea, Indian Ocean to examine the precise timing and cause of the disappearance of elongated taxa as well as their ecological preference. Our study reveals that elongated species prefer warm and low to intermediate food condition. This study documents the disappearance of 5 major species and 13 minor species from 0.6 to 0.2 Ma which is younger than the earlier estimates. We assume that change in 41–100 kyr climatic cycle along the MPT was responsible for a major decline in their number. However, amplified glacial–interglacial cycles along Mid-Brunhes (0.5–0.2 Ma) finally played a major role in their disappearance. Both of these consecutive events extended intensified cooling and dropped the deep-ocean temperature by which the shallow infaunal elongated species disappeared and deep-infaunal species survived.



中文翻译:

印度洋某些拉长的类群消失的时间和原因:NGHP Hole 17A的研究

在整个中更新世过渡期(MPT)中,许多拉长的底栖有孔虫消失了,通常被称为' Stilostomella灭绝”。世界各地的多个地方都报道了这一事件,据信大多数拉长的底栖生物家族在0.76-0.5 Ma范围内消失了。假定冷的底部水的存在触发了它们的消失。本研究是对从印度洋安达曼海国家天然气水合物计划洞17A收集的沉积物岩心进行的,以研究延长的类群消失的确切时间和原因,以及它们的生态偏好。我们的研究表明,拉长的物种更喜欢温暖和低至中等的食物条件。这项研究记录了从0.6到0.2 Ma的5种主要物种和13种次要物种的消失,这比早先的估计还年轻。我们假设沿着MPT的41-100 kyr气候周期的变化是造成其数量大幅下降的原因。然而,沿中布鲁斯(0.5-0.2 Ma)的扩大的冰间期循环最终在其消失中发挥了重要作用。这两个连续的事件都扩大了冷却,并降低了深海温度,从而使浅层的臭名昭著的物种消失,深层的臭名昭著的物种得以生存。

更新日期:2020-06-03
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