Tethyan magnetostratigraphy from Pizzo Mondello (Sicily) and correlation to the Late Triassic Newark astrochronological polarity time scale
Tethyan magnetostratigraphy from Pizzo Mondello (Sicily) and correlation to the Late Triassic Newark astrochronological polarity time scale
复制标题
DOI：
10.1130/b25326.1
复制
发表时间：
2004-09
影响因子：
4.9
通讯作者：
G. Muttoni;D. Kent;P. Olsen;P. Stefano;W. Lowrie;S. Bernasconi;F. Hernández
中科院分区：
文献类型：
--
作者：
G. Muttoni;D. Kent;P. Olsen;P. Stefano;W. Lowrie;S. Bernasconi;F. Hernández
本文介绍了西西里蒙代洛峰上三叠统海相灰岩剖面的磁性地层学和稳定同位素地层学，并对已发表的生物地层学资料进行了回顾，这些资料可用于确定该剖面牙形石Carnian-Norian和NorianRhaetian界线的位置。Mondello峰为海洋生物地层学和化学地层学数据与大陆纽瓦克天文年代学极性时间尺度（APTS）的磁性地层对比提供了良好的潜力，以发展一个完整的晚三叠世时间尺度。相对稳定的δ 18 O平均值（以0‰为中心）是Mondello峰Cherty灰岩几乎没有遭受成岩作用叠加的有力证据。牙形石Carnian-Norian界线位于δ 13 C正移点上方12.5m处。应用统计学方法对蒙德洛峰到纽瓦克的磁性地层对比进行了评价。两个相关选项具有最高的相关系数。在选项#1中，蒙德洛峰的底部与纽瓦克APTS的中间部分相关，而在选项#2中，蒙德洛峰的底部开始朝向纽瓦克APTS的早期部分。我们更倾向于选项2，其中基于牙形刺的Carnian-Norian边界及其密切相关的正δ 13 C偏移对应于约100 °的纽瓦克磁带E7。228 - 227 Ma（采用纽瓦克天体年代学），意味着一个持续时间约为2000万年的漫长诺里安，和约600万年的雷氏体。持续时间事实上，这些年龄与晚三叠世时标校准可用的少数高质量放射性测年并不矛盾。基于其良好的暴露性，可达性，地层厚度和连续性，以及多种年代地层对比的可能性，我们建议将蒙德洛峰作为全球地层剖面和诺利安基底点。
We present the magnetostratigraphy and stable isotope stratigraphy from an expanded (~430-m-thick) Upper Triassic marine limestone section at Pizzo Mondello, Sicily, and review published biostratigraphic information that can be used to defi ne the location of the conodont Carnian-Norian and NorianRhaetian boundaries in this section. Pizzo Mondello offers good potential for magnetostratigraphic correlation of marine biostratigraphic and chemostratigraphic data with the continental Newark astrochronological polarity time scale (APTS) for development of an integrated Late Triassic time scale. The relatively stable average values of δ 18 O centered on 0‰ are a strong indication that the Cherty Limestone at Pizzo Mondello suffered very little diagenetic overprinting. The conodont Carnian-Norian boundary is located 12.5 m above a positive shift of δ 13 C. A statistical approach was applied to evaluate various Pizzo Mondello to Newark magnetostratigraphic correlations. Two correlation options have the highest correlation coeffi cients. In option #1, the base of Pizzo Mondello correlates with the middle part of the Newark APTS, whereas in option #2, the base of Pizzo Mondello starts toward the early part of the Newark APTS. We prefer option #2 in which the Carnian-Norian boundary based on conodonts, as well as its closely associated positive δ 13 C shift, correspond to Newark magnetozone E7 at ca. 228‐227 Ma (adopting Newark astrochronology), implying a long Norian with a duration of ~20 m.y., and a Rhaetian of ~6 m.y. duration. These ages are in fact not inconsistent with the few high-quality radiometric dates that are available for Late Triassic time scale calibration. Based on its good exposure, accessibility, stratigraphic thickness and continuity, and multiple chronostratigraphic correlation possibilities, we propose Pizzo Mondello as global stratigraphic section and point for the base of the Norian.