Early Silurian sea-level changes
Early Silurian sea-level changes
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DOI：
10.1017/s0016756898008917
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发表时间：
1998-07
影响因子：
2.3
通讯作者：
D. Loydell
中科院分区：
文献类型：
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作者：
D. Loydell
全球海平面在志留纪早期显著波动，可能是由于冈瓦那南美部分冰盖的消长所致。志留纪的最高海平面是由泰利钦的上克拉珀斯-下格里斯托尼斯生物带和螺旋线-下拉普沃斯生物带记录的。其他高位出现在埃罗伊纪早期、Convolutus带(阿罗纪中期)、Guerichi带和晚图鲁瓦图斯带(Telychian早期)和Sheinwodian早期。低海平面的特点是Argenteus和sedgwickii带(Aeronian)、Utilis亚带(Guerichi晚期-早期涡轮亚带，Telychian早期)、Telychian晚期(开始于拉普沃伊中带)，以及在Sheinwodian晚期和最早的Hmer ian经历了一段显然仅有小幅海平面波动的时期后，Hmer ian中晚期，特别是早期Nassa带。下志留统的相(和动物群)变化不支持杰普森和S等人的P和S模式，但与本文提出的海平面变化一致。泰利钦中期海相红层似乎是在海平面小幅下降期间沉积的，而不是像以前所说的那样是在海侵事件期间沉积的。由于目前在早志留世深水(笔石学)和浅水(陆壳)层序对比中可能存在的精度不足，阻碍了本文提出的海平面曲线与过去建立的海平面曲线的比较。提高这种关联的精确度应该是未来研究的优先事项。
Global sea-level fluctuated markedly during the early Silurian, probably as a result of the waxing and waning of ice-sheets in the South American portion of Gondwana. The highest sea-levels of the Silurian are recorded by the Telychian upper crispus–lower griestoniensis and spiralis–lower lapworthi biozones. Other highstands occurred in the early Aeronian, during the convolutus Zone (mid Aeronian), guerichi Zone and late turriculatus Zone (early Telychian), and early Sheinwoodian. Low sea-levels characterized much of the argenteus and sedgwickii zones (Aeronian), the utilis Subzone (late guerichi–early turriculatus zones, early Telychian), the late Telychian (commencing in the mid lapworthi Zone) and, after a period of apparently only small amplitude sea-level fluctuations in the late Sheinwoodian and earliest Homerian, the mid–late Homerian, in particular the early nassa Zone. Facies (and faunal) changes in the Lower Silurian do not support the P and S model of Jeppsson and others, but are consistent with the sea-level changes proposed herein. Mid Telychian marine red beds appear to have been deposited during a minor sea-level fall immediately after a period of very high sea-levels, rather than during a transgressive episode as previously suggested. Comparison of the sea-level curve presented herein with those constructed in the past is hampered by the lack of precision currently possible in the correlation of early Silurian deep water (graptolitic) and shallow water (shelly) sequences. Improving the precision of this correlation should be a priority for future research.