Holocene volcanism trends from south-central Alaska tephra records: exploring linkages to climate
Abstract
There is complex interconnectivity between magma, the lithosphere, and climate, whereby volcanism both influencesand can be influenced byclimate. One mechanism for the climate-volcanism link may be the loading and unloading of glaciers, which suppresses or enhances dyke propagation. Using cores collected from lakes and bogs near Anchorage and the Cook Inlet area, south-central Alaska, we explore the frequency of Holocene tephra falls. We compiled these records to put the regional volcanic history in the broader context of northern hemisphere volcanic sulphate loading of the stratosphere and Cordilleran ice sheet fluctuations. We cataloged over 500 tephra bed observations and found that tephra-fall frequency in our dataset does not change significantly on multi-millennial time scales. However, at multi-centennial time scales, we find noticeable heterogeneity occurs and that some sites exhibit correlated tephra histories. These shorter-term variations, including excursions to higher and lower frequency, appear loosely associated with modelled and reconstructed deglacial and Holocene ice loading changes. However, comprehensive modelling of glacial isostatic adjustment is required to test the hypothesized geophysical climate-volcanism linkage more fully. Northern hemisphere Holocene volcanic forcing is undoubtedly contributed to by volcanoes in Iceland, Japan, the Cascades, and Kamchatka, amongst other regions. However, through correlation with Greenland ice core sulphate concentration and new bipolar sulphur injection data of Sigl et al., HoVol, we find a substantial component of variance in northern hemisphere stratospheric sulphur loading over time can be explained by changes in volcanism recorded in Alaska. In particular, the relatively high concentration/frequency of sulphate aerosols in Greenland ice between ~9 and 7 ka is correlated with the highest tephra fall frequency in our compilation. This work provides a basis for better understanding the influence of crustal strain, glacial loading, and the interconnections between climate and volcanic activity.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2021
- Bibcode:
- 2021AGUFM.V52A..03B