THE EARLY BARREMIAN WARM PULSE AND THE LATE BARREMIAN COOLING: A HIGH-RESOLUTION GEOCHEMICAL RECORD OF THE BOREAL REALM
THE EARLY BARREMIAN WARM PULSE AND THE LATE BARREMIAN COOLING: A HIGH-RESOLUTION GEOCHEMICAL RECORD OF THE BOREAL REALM
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DOI：
10.2110/palo.2010.p09-029r
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发表时间：
2010-01-01
期刊：
影响因子：
1.6
通讯作者：
Mutterlose, Joerg
中科院分区：
文献类型：
--
作者：
Malkoc, Matthias;Mutterlose, Joerg
本文分析了北部巴雷米尔平原（英格兰东北部和德国西北部）289块钙辉石的微量元素和同位素组成。氧同位素特征表明，所有7个剖面的古温度变化相似。可以认识到气候演化的三个不同阶段。早巴雷米亚寒期（Praeoxyteuthis pugio belenite Zone）是巴雷米亚晚期（Aulacoteuthis spp. belenite Zone）的一个显著增温事件。这个温暖的脉冲有一个相对较短的峰值（类似于500摄氏度），伴随着广泛的缺氧底水条件，并记录了整个瓦兰吉尼亚-巴雷米亚北部地区的最高温度。晚巴雷米亚（Oxyteuthis brunsvicensis、O germanica和O. depressa）蛭石岩带的8180值相对正，反映了一个冷却阶段。Mg/Ca趋势支持了对氧数据的古温度解释。巴雷米统碳同位素曲线由早期的1‰增加到晚期的30‰。这一趋势可能反映了巴雷米亚海洋碳收支的全球信号，并与北纬地区南部富toc沉积物的广泛沉积和特提斯地区乌尔古尼亚碳酸盐岩台地的进积有关。然而，有证据表明，古生物因素在稳定碳同位素的结合中所起的作用可能比迄今为止认为的要重要得多。在从一个30厘米厚的地层中采集的单特异钙辉石种群中，δ C-13信号显示出千分之1.5的变化。与温度或食物变化相关的代谢活动的个体发生变化可以解释分异率的变化，从而导致个体发生控制的生物分异。
A total of 289 belemnite guards was analyzed front the Boreal Barrermian (northeastern England and northwestern Germany) for their trace elements and isotopic composition. The oxygen-isotope signature shows similar paleotemperature variations for all seven sections investigated. Three different phases of climatic evolution can be recognized. An earliest Barremian cool phase (Praeoxyteuthis pugio belemnite Zone) is followed by a distinctive warming event in the late early Barremian (Aulacoteuthis spp. belemnite Zone). This Aulacoteuthis warm pulse has a relatively short-term peak (similar to 500 kyr), which accompanies widespread anoxic bottom-water conditions and records the highest temperature throughout the Valanginian-Barremian in the Boreal Realm. The late Barremian (Oxyteuthis brunsvicensis, O germanica, and O. depressa belemnite Zones) is characterized by relatively positive 8180 values reflecting a cooling phase. This paleotemperature interpretation of the oxygen data is supported by the Mg/Ca trends. The carbon isotope curve of the Barremian shows an increase from 1 parts per thousand in the early to 30 parts per thousand in the late Barremian. This trend may reflect the global signal of the carbon budget of Barremian oceans and be related to the widespread deposition of TOC-rich sediments in the southern part of the Boreal Realm and the progradation of the Urgonian carbonate platforms in the Tethys. There is evidence, however, that paleobiological factors may have played a much more important role in the incorporation of stable carbon isotopes than hitherto thought. In a monospecific belemnite population collected from one 30-cm-thick interval, the delta C-13 signal shows a variation of 1.5 parts per thousand. Ontogenetic changes in the metabolic activity linked to temperature or food changes may explain changes in the fractionation rate, resulting in an ontogenetically controlled biofractionation.