Clumped and oxygen isotope sclerochronology methods tested in the bivalve Lucina pensylvanica
Clumped and oxygen isotope sclerochronology methods tested in the bivalve Lucina pensylvanica
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DOI：
10.1016/j.chemgeo.2023.121346
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发表时间：
2023-01
期刊：
影响因子：
3.9
通讯作者：
Jade Z. Zhang;S. Petersen
中科院分区：
文献类型：
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作者：
Jade Z. Zhang;S. Petersen
保存在地质记录中的地球化学特征可用于重建过去的平均温度和季节性，但为了准确地应用过去的任何地球化学代用方法，必须对记录的代用指标与现代环境中的温度之间的关系进行严格的研究。在这里，我们评估多种同位素技术的能力，正确地记录平均年温度和季节性的bivalveLucina pencaperica。我们比较了基于亚年度分辨率δ 18 O、季节性目标和连续高分辨率（H.R.）研究人员将使用基于同位素（Δ47）的成团测温方法以及每种方法的多种数据处理方法，以确定哪种方法最符合已知的现代温度（最高和最低绝对温度以及年度温度范围），目的是确定用于化石贝壳的理想采样方案。国际劳工组织从7个站点收集的penneicashell，我们没有观察到平均温度或季节性偏差。年平均温度最好通过平均所有季节目标Δ47温度来匹配。季节性的最佳匹配是在取差值之前，对所有夏季和所有冬季的δ 18 Ocarb温度进行平均。在应用于连续高分辨率Δ47温度的两种数据处理方法中，“数据优化”显然更适合解决较小的季节温差。与此相反，“数据平滑法”产生的温度记录不受季节极值的先验分配的影响，并且同时具有检测δ 18 Ows的年际变化的能力。Δ 47方法必须平衡采样分辨率和生长速率。如果采样分辨率相对于生长速率足够高（101 pt./月或更长时间），我们建议使用连续高分辨率Δ47温度测量并进行数据平滑。如果由于生长速度缓慢或贝壳尺寸不足而无法实现这一分辨率，我们建议将基于亚年度δ 18 Ocarb的温度重建和基于季节性目标的Δ47温度重建配对，以获取温度的季节范围和绝对温度极值。
Geochemical signatures preserved within the geologic record can be used to reconstruct past mean temperature and seasonality, but in order to accurately apply any geochemical proxy method in the past, a rigorous study of how the recorded proxy is related to temperature in the modern setting must be conducted. Here, we assess the ability of multiple isotope techniques to correctly record mean annual temperature and seasonality in the bivalveLucina pensylvanica. We compare subannual-resolution δ18O-based, seasonally-targeted and continuous high-resolution (H.R.) clumped isotope (Δ47)-based thermometry methods, as well as multiple data treatment methods for each, to determine which approach best matches known modern temperatures (maximum and minimum absolute temperature and annual temperature range), with the goal of defining the ideal sampling scheme for use on fossil shells. InL. pensylvanicashells collected from 7 sites, we observe neither mean temperature nor seasonal biases. Mean annual temperature is best matched by averaging all seasonally-targeted Δ47-temperatures. Seasonality is best matched by averaging δ18Ocarb-based temperatures from all summers and all winters before taking the difference. Of two data treatment approaches applied to the continuous high-resolution Δ47-based temperatures, “data optimization” is apparently better at resolving smaller seasonal temperature differences. In contrast, “data smoothing” produces a temperature record unbiased by prior assignment of seasonal extremes and has the simultaneous ability to detect subannual variability in δ18Ow.However, accurate application of H.R. Δ47methods must balance sampling resolution and growth rate. If sampling resolution is high enough relative to the growth rate (∼1 pt./month or better), we recommend continuous high-resolution Δ47-thermometry with data smoothing. If this resolution cannot be achieved due to slow growth rates or insufficient shell size, we recommend pairing subannual δ18Ocarb-based and seasonally-targeted Δ47-based temperature reconstruction to acquire seasonal range in temperature and absolute temperature extremes.