TRACING BURIAL HISTORY AND SEDIMENT RECYCLING IN A SHALLOW ESTUARINE SETTING (COPANO BAY, TEXAS) USING POSTMORTEM AGES OF THE BIVALVE MULINIA LATERALIS
TRACING BURIAL HISTORY AND SEDIMENT RECYCLING IN A SHALLOW ESTUARINE SETTING (COPANO BAY, TEXAS) USING POSTMORTEM AGES OF THE BIVALVE MULINIA LATERALIS
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利用双壳类 Mulinia Lateralis 的死后年龄追踪浅河口环境（德克萨斯州科帕诺湾）的埋藏历史和沉积物回收
DOI：
10.2110/palo.2014.063
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发表时间：
2015
影响因子：
3.6
通讯作者：
D. Kaufman
中科院分区：
文献类型：
--
作者：
T. Olszewski;D. Kaufman
摘要德克萨斯州科帕诺湾沉积柱顶部0-10 cm处的Mulinia lateralis贝壳的年龄谱显示出三个不同的种群：年轻人口的分布高度偏态，范围从0到1岁，中年人口的分布更加对称，范围从1到10岁，峰值为104岁，年龄在100岁到10000岁之间的非常古老的人群。年轻的人口被解释为记录的快速损失的贝壳从taphonomically活跃区或附近的沉积物表面。中年人口被解释为记录了一个隔离人口的贝壳，有时间积累下面的埋藏活动区。虽然表面年龄谱不同的沉积环境和在不同的位置，这些人口都存在于所有采样相在海湾内的多个位置，表明表面年龄谱的总体控制影响整个海湾。非常古老的表面人口只存在于海湾边缘的网站，并解释为代表贝壳挖出侵蚀全新世沉积物。在阿兰萨斯河河口附近的海湾边缘地区采集的一个86厘米长的岩心包含了从1年到14,000年的贝壳，但没有按照地层顺序保存下来。缺乏地层顺序和存在明显的中断，在死后的年龄分布表明，67%的壳在核心回收旧存款，导致在2-3个数量级的增加量的时间平均在沉积物柱相对于表面样品。
ABSTRACT Age spectra of Mulinia lateralis shells from the top 0–10 cm of the sediment column in Copano Bay, Texas, show three distinct populations: a young population with a highly skewed distribution ranging from 0 to 1 years, a middle-aged population that is more symmetrical ranging from 1 to 10 years with a peak ∼ 4 years, and a small, very old population ranging from 100 to > 10000 years. The young population is interpreted to record the rapid loss of shells from the taphonomically active zone at or near the sediment surface. The middle-aged population is interpreted to record a sequestered population of shells that has had time to accumulate below the taphonomically active zone. Although surface age spectra differ among depositional environments and at different locations, both of these populations are present in all sampled facies at multiple locations within the bay, indicating that the overarching controls on surface age spectra affect the entire bay. The very old surface population is present only in bay-margin sites and is interpreted to represent shells exhumed from eroding Holocene deposits. An 86-cm-long core taken at a bay-margin site near the mouth of the Aransas River contains shells spanning < 1 to 14,000 years but not preserved in stratigraphic order. The lack of stratigraphic order and the presence of distinct breaks in the postmortem age distribution suggest that 67% of shells in the core were recycled from older deposits, resulting in a 2–3 order of magnitude increase in the amount of time averaging in the sediment column relative to surface samples.