A Dendrochronological Investigation of Influences on Tree Growth in the Permian and Triassic, Antarctica

• Main Author: Dahlseid, Aidan
• Format: Text
• Language: English
• Published: 2021
• Subjects: Shackleton; Shackleton Glacier; Transantarctic Mountains; Antarc*; Antarctica
• Online Access: http://archives.gac.edu/cdm/ref/collection/irstudents/id/4188

Dendrochronology is applied to Permian and Triassic fossil wood from the central Transantarctic Mountains, Antarctica. This time interval, marked by greenhouse warming and culminating in the end-Permian mass extinction, may provide an analogue for present-day climate change. The fossil material studied is from paleo-polar forests, unique ecosystems that have no modern counterpart. Ring widths were measured in samples of Permian, latest Permian, and Triassic age from three locations near the Shackleton Glacier (86°S, ~170°E). For each location, samples were cross-matched to each other using dendrochronology software. To remove age-related growth trends, a ring width index (RWI) was calculated for all cross-matched samples. Successful cross-matches for six of the Permian samples result in a chronology of 42 years, while successful cross-matches for six of the latest Permian samples result in a chronology of 112 years. Average RWI curves for each chronology were analyzed and compared to previous data from Gulbranson et al. (2020), revealing that statistical distributions of RWIs and periodicities are remarkably similar between two study sites that are ~1000 km apart. Notably, periodicities increased from the Permian to the Triassic even when dominant tree taxa remained the same, and periodicities remained similar over a change in dominant tree taxa from the latest Permian to the Triassic, suggesting these trends were primarily due to changes in climate rather than ecology. In addition, the lack of an 11-year periodicity suggests the 11-year solar cycle was not a prominent factor influencing tree growth in the south polar latitudes during this time. A Dendrochronological Investigation of Influences on Tree Growth in the Permian and Triassic, Antarctica By Aidan Dahlseid A report submitted in partial fulfillment of the requirements of the degree of Bachelor of Arts (Geology) at Gustavus Adolphus College 2021 Gustavus Student Repository - Thesis 2 A Dendrochronological Investigation of Influences on Tree Growth in ...