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首页> 外文会议>International Conference on Geologic Problem Solving with Microfossils >TEST-SHAPE VARIABILITY OF AMPHISTEGINA D'ORBIGNY, 1826 AS APALEOBATHYMETRIC PROXY: APPLICATION TO TWO MIOCENE EXAMPLES
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TEST-SHAPE VARIABILITY OF AMPHISTEGINA D'ORBIGNY, 1826 AS APALEOBATHYMETRIC PROXY: APPLICATION TO TWO MIOCENE EXAMPLES

机译：Amphistegina d'Orbigny的测试形状变异，1826年作为apaleobathyhetric代理：应用于两个中生例子

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Solar energy (light) is essential for organisms that host algal symbionts. Hence, growth of these organisms is restricted to the photic zone. Among the larger benthic foraminifers, large rotaliids show changes in their test shapes when depth increases, becoming thinner and flatter in deeper environments. This morphological variability is shown clearly in the genus Amphistegina. In oligotrophic waters from the Indo-Pacific region, test shape can be mathematically expressed by the function Z_o= 2.592 T /D~(-2.293), where Z_o represents depth and T/D is the thickness-to-diameter ratio. Amphistegina test-shape distribution is strongly correlated with light extinction with depth. Light penetration depends on water transparency, which diminishes as biological productivity increases. Thus, Z_o must be corrected for mesotrophic environments where light penetration is more limited. In mesotrophic conditions, Amphistegina test shape can be expressed mathematically as Z_m = 1.037 T/ D~(-2.293) whereas in oligotrophic–mesotrophic transitional situations the equation is Z_(om) = 2.046 T / D~(-2.293). Z_o Z_m and Z_(om) can be used as quantitative bathymetric indicators. In the Latium–Abruzzi and Menorca carbonate platforms, paleodepths inferred from Z_m and Z_(om), respectively, are highly consistent with those obtained from the distribution of the red-algae associations. Thus, paleobathymetric models for both carbonate platforms have been constructed using Amphistegina T/D values as main indicators, supported by information from red algae and other biota. According to the inferred paleobathymetry, in the Latium–Abruzzi platform the inner ramp went from shoreline down to 10 m depth, the middle ramp from 10 m down to 35 m depth, and finally, the outer ramp corresponds to depths greater than 35 m. The Menorca platform paleobathymetric reconstruction indicates an inner ramp from 0 m down to 20 m depth, a middle ramp from 20 m down to 40 m, a ramp slope from 40 m down to 80 m, and, finally, an outer ramp no deeper than 100 m. Bathymetric ranges in the Menorca platform, deeper than those from the Latium–Abruzzi ramp, are consistent with greater light penetration.The Amphistegina T / D index can also be used as a sediment-transport indicator. In the Menorca platform, sediment transport from the inner ramp down to the middle ramp, and even down to the lower ramp slope, are indicated by thick, ex situ Amphistegina specimens in relatively deep environments. The distribution of red algae and the co-occurrence of shallow organisms such as epiphytic foraminifers and fragments of hermatypic corals (Porites) confirm downslope transport and the role of the inner-ramp factory as an important sediment source.
机译：太阳能（Light）对于宿主共生的生物是必不可少的。因此，这些生物的生长仅限于光区。在较大的底栖传染媒es中，大型旋转大石上显示了当深度增加时它们的测试形状的变化，在更深的环境中变得更薄并更平坦。在Amphistegina属中清楚地显示了这种形态变异性。在来自靛蓝区的寡替氏型水域中，测试形状可以由Z_O = 2.592 T /d ~(-293）的数学方式，其中Z_O表示深度，T / D是厚度到直径的比率。 Amphistegina测试形状分布与深度的光灭火强烈相关。光渗透取决于水透明度，随着生物生产率的增加而减少。因此，必须校正Z_O，用于渗透渗透率更有限。在培素养殖条件下，Amphistegina测试形状可以在数学上以Z_M = 1.037 T / D〜（-2.293）表示，而在寡噬细胞 - 培养的过渡情况下，等式是Z_（OM）= 2.046 T / D〜（-2.293）。 Z_O Z_M和Z_（OM）可用作定量碱基指示器。在亚空原和核酸碳酸盐平台中，分别从Z_M和Z_（OM）推断的古部门与从红藻类关联的分布中获得的那些高度一致。因此，使用Amphistegina T / D值作为主要指标构建了碳酸盐平台的古地质型模型，由红藻类和其他Biota的信息支持。根据推断的古地妥少，在亚空金古道斯平台上，内舷坡道从海岸线到10米深度，中间斜坡从10米到35米深度，最后，外舷坡道对应于35米的深度。 Menorca平台古地质重建表示从0米到20米深度的内斜坡，中间斜坡从20米到40米，斜坡从40米下降到80米，最后，外斜坡不比100米。梅罗达平台中的碱基范围比来自Abruzzi坡道的更深，与更大的光渗透相一致。Amphistegina T / D指数也可以用作沉积物输送指示器。在Menorca平台中，从内斜坡到中间斜坡的沉积物运输，甚至达到下斜坡斜坡，在相对深沉的环境中表示厚的前型amphistegina标本。红藻和浅生物的分布和浅生物的共发，如骨骺对氨基胺（Porate）的碎片（Porite）确认了倒流运输和内斜坡工厂作为重要沉积物来源的作用。

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