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![Did Toba play a role in an observed “bottleneck” in
human mitochondrial genetic diversity?
Maybe. [Ambrose 1998]
No. [Petraglia et al., 2007]
see review by Williams et al., 2012
NOTE: H. floresiensis
lived during this time,
discovered in cave
within Toba ash fall zone](https://image.slidesharecdn.com/cobbhighres2015-150603124602-lva1-app6892/85/The-Toba-super-eruption-micro-scale-traces-of-a-global-scale-climate-event-4-320.jpg?cb=1433335824)
Uploaded byKim Cobb
The Toba super-eruption: micro-scale traces of a global-scale climate event?
The document discusses the Toba super-eruption, estimated to have occurred approximately 73,880 years ago, and its potential impact on global climate and human evolution. It examines various studies and models regarding the eruption's effects on regional hydroclimate and the responses recorded in geological samples, such as stalagmites. The research aims to understand the eruption's magnitude and its implications for climatic changes and human genetic diversity during that period.
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The Toba super-eruption: micro-scale traces of a global-scale climate event?
- 1. The Toba super-eruption: Micro-scaletraces of a global-scale climate event? Kim M. Cobb Stacy Carolin, Jessica Moerman, Ellery Ingall, Luke Chambers, Amelia Longo Georgia Inst. of Technology Nele Meckler, Jess F. Adkins Caltech Lydia Finney Argonne National Lab Victoria Smith Oxford Syria Lejau, Jenny Malang, Brian Clark, Alison Pritchard Gunung Mulu National Park Andrew Tuen University Sans Malaysia
- 2. The Toba super-eruption: 73.88 ±0.6 kybp (Storey et al., 2012) ~3,000km3 DRE VEI of 8 Mulu Miller and Wark, 2008
- 3. Miller and Wark,2008 Relative eruption magnitudes
- 4. Did Toba playa role in an observed “bottleneck” in human mitochondrial genetic diversity? Maybe. [Ambrose 1998] No. [Petraglia et al., 2007] see review by Williams et al., 2012 NOTE: H. floresiensis lived during this time, discovered in cave within Toba ash fall zone
- 5. Volcanoes impact globalclimate: Instrumental data 100x smaller than Toba 300x smaller than Toba Kelly et al., 1996 eruption
- 6. Volcanoes impact globalclimate: Paleoclimate data IPCC, 2013 data-model comparison provides critical constraints on climate sensitivity: temperature response to change in radiative forcing
- 7. Volcanoes impact globalclimate, but how much? Fact: models tend to cool more than paleoclimate data suggest problem with models? (e.g. Timmreck et al., 2010) or data? (Mann et al., 2012, 2013; Anchukaitis et al., 2012) IPCC, 2013
- 8. Robock et al.,2009 Modeling Toba’s effects in CCSM3 dire effects in first 10yrs dissipate in ~30yrs
- 9. BEFORE +1-4yr Robock et al.,2009 huge vegetation response across entire tropics in model need to look i) regionally ii) at hydroclimate iii) and model δ18OR for comparison to proxy records
- 10. Modeling Toba’s effectsin MPI-ESM Timmreck et al., 2012 smaller global response than CCSM3, but very large in some regions global T Toba
- 11. Borneo stalagmites asrecords of regional climate and environmental history U/Th dated many overlapping samples to test reproducibility oxygen isotopes reflect regional hydroclimate (Moerman et al., 2013, 2014)
- 12. stalagmite oxygen isotope records reproducible revealmany large millennial-scale excursions towards dry conditions (blue bars = Heinrich events) Carolin et al., Science 2013 MULU GREENLAND HULU MULU
- 13. largest anomaly associated with Tobasuper-eruption also captured as out-sized event in Hulu stalagmite oxygen isotopes dry conditions for ~1,000yrs GREENLAND HULU MULU
- 14. The records of t throughthe oft-time co regional cli sediment c shows no s associated even while changes rec Similarly, L major clim Toba ash la (located ov stalagmites millennial- samples tha magnitude mirrored in d18 O record (Figure 1). proxy recor sharp, prolo 2cm layer o al., 2001). Ear sized erupt on Earth’s Timmreck 65 8077747168 65 8077747168 Age (kybp) ice$core$$ sulfate$peaks$ 40Ar/39Ar(( Toba(date( -10 -9.5 -9 -8.5 δ18O(‰) -8 -7 -6 δ18O(‰) 27.0 26.5 26.0 SST(°C) -40 -42 -44 δ18O(‰) -47 -48 -49 δ18O(‰) Borneo caves Hulu/ Sanbao South China Sea NGRIP EDML wet dry warm cold warm cold warm cold wet dry GS20 A closer look Carolin et al., 2013 Wang et al., 2001 Wang et al., 2008 Huang et al., 2001 NGRIP, 2004 EPICA, 2006 Svensson et al., 2012 ash layer in South China Sea corresponds to initiation of cooler reconstructed SST of dark subhedral biotite and rarer hornblende crystal. The gradational contacts of the tephra layer with host sediments in the top and bottom are a total of 20 cm in thickness. This suggests that the tephra had been reworked by bottom current and biotubation, which likely diffused the tephra within the host sediments. Two size fractions (63–150 and 150 mm) were separated and sampled for morphological and geochemical analyses. The morphology of the glass shards was studied by the Riguku Scanning Electron Microscopy (SEM) at the Department of Geology, National Taiwan Univer- sity. The major element compositions of the glass shards and mineral grains were determined using a JEOL JXA-8900R Electron Micro-Probe Analyzer (EPMA) at the Institute of Earth Sciences, Academia Sinica, Taiwan. Operating conditions were 15 kV, 10 nA and were focused ( 1 mm) for accelerated voltage, probe current and beam diameter. The data were processed using the ZAF correction routine. S.-R. Song et al. / Marine Geology 167 (2000) 303–312306 200µm
- 15. The records of t throughthe oft-time co regional cli sediment c shows no s associated even while changes rec Similarly, L major clim Toba ash la (located ov stalagmites millennial- samples tha magnitude mirrored in d18 O record (Figure 1). proxy recor sharp, prolo 2cm layer o al., 2001). Ear sized erupt on Earth’s Timmreck 65 8077747168 65 8077747168 Age (kybp) ice$core$$ sulfate$peaks$ 40Ar/39Ar(( Toba(date( -10 -9.5 -9 -8.5 δ18O(‰) -8 -7 -6 δ18O(‰) 27.0 26.5 26.0 SST(°C) -40 -42 -44 δ18O(‰) -47 -48 -49 δ18O(‰) Borneo caves Hulu/ Sanbao South China Sea NGRIP EDML wet dry warm cold warm cold warm cold wet dry GS20 Carolin et al., 2013 Wang et al., 2001 Wang et al., 2008 Huang et al., 2001 NGRIP, 2004 EPICA, 2006 Svensson et al., 2012 multiple sulfate peaks in Antarctic ice core tied to sulfate peaks in Greenland relationship to Toba eruption(s)? A closer look
- 16. Research questions: 1) Howmany times did Toba erupt ~74,000yrs ago? And with what relative sizes? 2) What were the regional hydroclimate impacts of the eruption(s)? 3) Did Toba-related climate effects in the Western Pacific have an effect on global climate? Did Toba shape the timing or depth of GS20?
- 17. Approach: Find Toba’s volcanicmarkers in the Borneo stalagmites. Compare to oxygen isotope-based climate record in same stalagmites. AB
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- 20. Preliminary SIMS Sulfurprofile 10μm beam = ~2.2yrs 20μm sampling res = 4yrs data from Stacy Carolin initiation of regional drying ~550yrs Toba eruptions? younger older
- 21. Next steps: Geochemically fingerprint i)Toba ash samples ii) Mulu clay samples Compare to synchrotron/SIMS scans across i) Toba horizon ii) known hiatuses Elements of interest (Fe, Si, S, Br, K, Al) *see review by Frisia et al., 2012 Lane et al., 2013 Mermut and Cano, 2001