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Biogeodynamics of Cretaceous marine carbonate production
Earth-Science Reviews ( IF 10.8 ) Pub Date : 2023-02-10 , DOI: 10.1016/j.earscirev.2023.104341
Thomas Steuber , Hannes Löser , Joerg Mutterlose , Mariano Parente

We have compiled stratigraphic ranges of genera of calcareous nannofossils, calcispheres, planktonic foraminifers, larger benthic foraminifers, corals and rudists bivalves, and species of dasycladalean green algae. These taxa comprise the main planktonic and benthic carbonate producers of the Cretaceous, a period of exceptionally high sea level and palaeotemperatures that was characterized by unique assemblages of benthic carbonate producers and the significant rise in pelagic carbonate sedimentation. The autecology, physiological control on calcification, and carbonate-production potential of these groups is summarized. The observed diversity patterns are compared with proxy data of Cretaceous climate and seawater chemistry to elucidate the effect of environmental change on carbonate production and sedimentation.

Two characteristic patterns are recognized. Diversity of calcareous nannofossils, calcispheres, planktonic foraminifers and corals trace the evolution of Cretaceous sea-level, while the diversity of dasycladalean algae, larger benthic foraminifers, corals and rudist bivalves show significant reductions at the level of oceanic anoxic events (OAEs). Benthic carbonate producers except for corals thus appear to have been more vulnerable to environmental change, and these general patterns appear to be unrelated to the autecology of the taxa investigated. The expansion of suitable habitats during episodes of high sea level and high temperatures appears to have been a more important control of diversity in calcareous nannofossils, planktonic foraminifers, and corals than changes in seawater chemistry. Aragonitic or aragonite-dominated benthic carbonate producers are most affected during extinction events related to OAEs, and there is a general trend of decreasing aragonite dominance throughout the Cretaceous. This is compensated by the extensive formation of calcitic hemipelagic chalk since the Cenomanian. The trend of decreasing aragonite dominance is independent of the level of biological control on calcification in the different taxa affected. The demise of aragonitic or aragonite-dominated carbonate producers at OAE1a (early Aptian) and OAE2 (Cenomanian–Turonian boundary interval) may be related to short episodes of reduced seawater carbonate-saturation caused by short-lived injections of CO2 from large igneous provinces that initiated OAEs. For OAE1a, this scenario also explains the retreat of carbonate platforms to low latitudes in the early Aptian, as sea-surface water typically has a higher carbonate saturation in warm, lower than in cooler, higher latitude waters. The gradual decrease of aragonite throughout the Cretaceous matches model simulations of seawater carbonate-saturation. An increase in the relative number of azooxanthellate coral genera following OAE1a and OAE2 suggests a disruption of photosymbiosis in the course of these global events due to high temperatures. However, the relative numbers of azooxanthellate genera continued to increase during the Late Cretaceous, when global temperatures declined. Due to the short residence time of major nutrients in seawater, these may have affected carbonate-producing ecosystems regionally. The recent patterns of benthic carbonate production being highest in oligotrophic environments cannot confidently be extrapolated to the Cretaceous.

Our database records ranges of genera at the substage level. Higher-resolution stratigraphical studies of neritic carbonate sequences are required to understand what aspect of environmental change in the sequence of events that unfolded in the context of OAEs caused the demise of benthic carbonate producers.



中文翻译:

白垩纪海相碳酸盐岩生产的生物地球动力学

我们编制了钙质超微化石、钙球、浮游有孔虫、较大的底栖有孔虫、珊瑚和红腹双壳类以及菊科绿藻属的地层范围。这些分类群包括白垩纪的主要浮游生物和底栖碳酸盐生产者,白垩纪是一段异常高的海平面和古温度,其特点是底栖碳酸盐生产者的独特组合和远洋碳酸盐沉积的显着增加。总结了这些组的生命生态学、钙化的生理控制和碳酸盐生产潜力。将观察到的多样性模式与白垩纪气候和海水化学的代理数据进行比较,以阐明环境变化对碳酸盐生产和沉积的影响。

识别出两种特征模式。钙质超微化石、钙球、浮游有孔虫和珊瑚的多样性追踪了白垩纪海平面的演变,而 dasycladalean 藻类、较大的底栖有孔虫、珊瑚和赤壳类双壳类动物的多样性在海洋缺氧事件 (OAE) 水平上显着减少。因此,除了珊瑚之外的底栖碳酸盐生产者似乎更容易受到环境变化的影响,而且这些一般模式似乎与所调查的分类群的进化生态学无关。与海水化学变化相比,高海平面和高温期间适宜栖息地的扩张似乎是对钙质超微化石、浮游有孔虫和珊瑚多样性的更重要控制。在与 OAE 相关的灭绝事件期间,文石或以文石为主的底栖碳酸盐生产商受到的影响最大,并且在整个白垩纪期间,文石优势呈下降趋势。自 Cenomanian 以来,大量形成的方解石半远洋白垩弥补了这一点。文石优势下降的趋势与受影响的不同类群中钙化的生物控制水平无关。OAE1a(早期 Aptian)和 OAE2(Cenomanian-Turonian 边界区间)文石或以文石为主的碳酸盐生产者的消亡可能与短期注入 CO2 引起的海水碳酸盐饱和度降低的短期事件有关 在整个白垩纪,文石的优势呈下降趋势。自 Cenomanian 以来,大量形成的方解石半远洋白垩弥补了这一点。文石优势下降的趋势与受影响的不同类群中钙化的生物控制水平无关。OAE1a(早期 Aptian)和 OAE2(Cenomanian-Turonian 边界区间)文石或以文石为主的碳酸盐生产者的消亡可能与短期注入 CO2 引起的海水碳酸盐饱和度降低的短期事件有关 在整个白垩纪,文石的优势呈下降趋势。自 Cenomanian 以来,大量形成的方解石半远洋白垩弥补了这一点。文石优势下降的趋势与受影响的不同类群中钙化的生物控制水平无关。OAE1a(早期 Aptian)和 OAE2(Cenomanian-Turonian 边界区间)文石或以文石为主的碳酸盐生产者的消亡可能与短期注入 CO2 引起的海水碳酸盐饱和度降低的短期事件有关2个来自发起 OAE 的大型火成岩省份。对于 OAE1a,这种情况也解释了碳酸盐岩台地在早期 Aptian 退缩到低纬度地区,因为海表水通常在温暖的水域中具有较高的碳酸盐饱和度,低于在较冷的高纬度水域中的碳酸盐饱和度。整个白垩纪文石的逐渐减少与海水碳酸盐饱和度的模型模拟相符。OAE1a 和 OAE2 之后偶氮黄藻珊瑚属的相对数量增加表明,由于高温,在这些全球事件的过程中光共生被破坏。然而,在白垩纪晚期,当全球气温下降时,偶氮黄藻属的相对数量继续增加。由于主要营养物质在海水中停留时间短,这些可能影响了区域性的碳酸盐生产生态系统。最近的底栖碳酸盐生产模式在贫营养环境中最高,不能自信地外推到白垩纪。

我们的数据库记录亚阶段级别的属范围。需要对浅海碳酸盐岩层序进行更高分辨率的地层学研究,以了解在 OAE 背景下展开的事件序列中环境变化的哪个方面导致了底栖碳酸盐岩生产商的消亡。

更新日期:2023-02-10
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