Tropical marine climate during the late Paleozoic ice age using trace element analyses of brachiopods

Matthew G. Powell*, Bernd R. Schöne, Dorrit E. Jacob

*Corresponding author for this work

Research output: Contribution to journalArticle

21 Citations (Scopus)

Abstract

The late Paleozoic ice age can be considered an important analogue to the modern ice age, but comparisons between the two time intervals have been hampered by the difficulty of resolving climatic changes that occur over short (e.g., seasonal) time scales in the Paleozoic record. As a first step toward overcoming these limitations, this study employed Mg/Ca trace element ratios sampled across the growth bands of six specimens of the brachiopod Composita to assess differences in tropical marine mean temperature and seasonality in Viséan and Moscovian time. These time intervals bracket the onset of the late Paleozoic ice age, which occurred in mid-Serpukhovian time, and thus provide a snapshot of climate changes from a greenhouse to an icehouse world. Shells were screened for diagenetic alteration by cathode luminescence and by comparing the values of Mn, Sr, Na, and B to those reported for modern brachiopods. In addition, a 87Sr/86Sr value, measured for one specimen, agreed with a published strontium isotope curve for the late Paleozoic Era. Both the mean and range of Mg/Ca values were larger in Viséan than Moscovian time, suggesting colder and less seasonal temperatures during the late Paleozoic ice age. The decline in seasonality was due to a greater proportional reduction of maximum values (which presumably represent summer temperatures) than minimum values. These relative differences between the pre-ice age and ice age tropical climate provide a first step toward understanding the broad patterns of seasonal-scale changes in temperature during a critical time in Earth's history.

Original languageEnglish
Pages (from-to)143-149
Number of pages7
JournalPalaeogeography, Palaeoclimatology, Palaeoecology
Volume280
Issue number1-2
DOIs
Publication statusPublished - 1 Sep 2009
Externally publishedYes

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