DeepCHALLA: Two Glacial Cycles of Climate and Ecosystem Dynamics from Equatorial East Africa

Verschuren, Dirk; Olago, Daniel; Rucina, Stephen M.; Odhengo, Peter O.

doi:10.5194/sd-15-72-2013

Cited by 16 publications

(14 citation statements)

References 16 publications

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“…In the southeastern foothills of Mt. Kilimanjaro, close to where this history has played out, lies Lake Chala, a relatively large and deep crater lake with a long and continuous sediment archive (Moernaut et al, 2010; Verschuren et al, 2013). The sediment record of Lake Chala has been studied intensively, yielding detailed palaeoclimate and palaeo-environmental data spanning the last 25,000 years (e.g., Barker et al, 2011; Meyer et al, 2020; Nelson et al, 2012; Sinninghe Damsté et al, 2011, 2012; Tierney et al, 2011; van Geel et al, 2011; Verschuren et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

Climate-human-landscape interaction in the eastern foothills of Mt. Kilimanjaro (equatorial East Africa) during the last two millennia

et al. 2020

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The Mt. Kilimanjaro region is known for its long history of intensive agriculture, but the temporal extent of human activity and its impact on the regional ecosystem are not well known. In this study, climate-human-landscape interactions during the past ~2200 years were examined using climate and vegetation proxies extracted from the continuous and high-resolution sediment record of Lake Chala. Ancient-to-modern regional human activity is documented against a backdrop of long-term vegetation dynamics in the low-elevation savanna woodland southeast of Mt. Kilimanjaro and riparian forest within Chala crater. During prolonged dry periods (~1170–1300 CE), succulent dry crater forest expanded relative to the moist lakeshore forest. The savanna landscape surrounding Chala crater was relatively stable through time, except that savanna grasses were stimulated by higher precipitation, consistent with the fuel-limited fire regime evidenced in the charcoal record. Expansion of subalpine ericaceous vegetation and a general decline in Afromontane forest taxa on Mt. Kilimanjaro after 550 CE may reflect a lowering of its upper forest line. The earliest robust signature of human influence on regional vegetation involves an increase in ruderal (weedy) plant taxa around 1100 CE, possibly associated with the development of Chagga homegardens and associated agroforestry in the submontane forest zone. A first hint of cereal agriculture (likely sorghum) is observed around 1550 CE, followed by a more robust signature from 1780 CE onwards which likely reflects the start of lowland irrigation agriculture. From 1780 CE we also find the first undisputed appearance of maize, introduced to East Africa about a century earlier.

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Section: Introductionmentioning

confidence: 99%

Climate-human-landscape interaction in the eastern foothills of Mt. Kilimanjaro (equatorial East Africa) during the last two millennia

et al. 2020

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“…The spatio-temporal properties of centennial and millennial variability are also poorly characterised, especially in tropical areas and before the last glacial-interglacial cycle, but such data are becoming available. For example, a current drilling project is hoped to deliver 200 ka of high-resolution climate data in central Africa (Verschuren et al, 2013). Such records will thus provide further opportunities to test our understanding of climate dynamics.…”

Section: Why We Need To Combine Modelling Frameworkmentioning

confidence: 99%

Challenges for Ice Age Dynamics: A Dynamical Systems Perspective

Crucifix¹,

Lenoir²,

Mitsui³

2016

Nonlinear and Stochastic Climate Dynamics

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This chapter is dedicated to the slow dynamics of the climate system, at time scales of one thousand to one million years. We focus specifically on the phenomenon of ice ages that has characterised the slow evolution of climate over the Quaternary. Ice ages are a form of variability featuring interactions between different large-scale components and processes in the climate system, including ice sheet, deep-ocean and carbon cycle dynamics. This variability 1 arXiv:1512.03557v1 [physics.ao-ph]

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“…Lake Chala (3.3° S, 37.7° E) is situated in a steep‐sided volcanic crater basin formed after a monogenetic parasitic eruption associated with Mt Kilimanjaro's most recent phase of volcanic activity. Based on the basal age of 25 ka for the upper, 14 C‐dated, 21.65 m of profundal sediments (Blaauw et al , ) and an extrapolated age model for the last 140 ka (Moernaut et al ), Verschuren et al () estimated the age of the complete ~210‐m sediment infill in Lake Chala at >250 000 years. The lake is 94 m deep with a surface area of 4.2 km 2 , and receives water only from direct rainfall, runoff from its steep crater walls and subsurface inflow originating from the percolation of rainfall onto the forest zone on Mt Kilimanjaro (Verschuren et al , ).…”

Section: Introductionmentioning

confidence: 99%

“…Its lower water column is permanently stratified, both today (Buckles et al ; Wolff et al , ) and over at least the last 25 000 years (Verschuren et al ). Consequently, Lake Chala accumulates undisturbed and near‐continuously laminated diatomaceous organic sediments, interrupted only by turbidites and tephras (Verschuren et al , ).…”

Section: Introductionmentioning

confidence: 99%

“…Verschuren et al , ; Barker et al , ; Damsté et al , ). In November 2016, as part of the International Continental Scientific Drilling Program, the DeepCHALLA project (Verschuren et al , ) retrieved a 215‐m long sediment sequence, nearly reaching the crater floor. This study utilises both the CHALLACEA and DeepCHALLA sequences to explore the record of basaltic scoria‐cone volcanism in the Mt Kilimanjaro area.…”

Section: Introductionmentioning

confidence: 99%

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History of scoria‐cone eruptions on the eastern shoulder of the Kenya–Tanzania Rift revealed in the 250‐ka sediment record of Lake Chala near Mount Kilimanjaro

Martin-Jones

Lane

Daele

et al. 2019

J Quaternary Science

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Reconstructions of the timing and frequency of past eruptions are important to assess the propensity for future volcanic activity, yet in volcanic areas such as the East African Rift only piecemeal eruption histories exist. Understanding the volcanic history of scoria‐cone fields, where eruptions are often infrequent and deposits strongly weathered, is particularly challenging. Here we reconstruct a history of volcanism from scoria cones situated along the eastern shoulders of the Kenya–Tanzania Rift, using a sequence of tephra (volcanic ash) layers preserved in the ~250‐ka sediment record of Lake Chala near Mount Kilimanjaro. Seven visible and two non‐visible (crypto‐) tephra layers in the Lake Chala sequence are attributed to activity from the Mt Kilimanjaro (northern Tanzania) and the Chyulu Hills (southern Kenya) volcanic fields, on the basis of their glass chemistry, textural characteristics and known eruption chronology. The Lake Chala record of eruptions from scoria cones in the Chyulu Hills volcanic field confirms geological and historical evidence of its recent activity, and provides first‐order age estimates for seven previously unknown eruptions. Long and well‐resolved sedimentary records such as that of Lake Chala have significant potential for resolving regional eruption chronologies spanning hundreds of thousands of years.

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DeepCHALLA: Two Glacial Cycles of Climate and Ecosystem Dynamics from Equatorial East Africa

Abstract: No abstract available. <br><br> doi:<a href="http://dx.doi.org/10.2204/iodp.sd.15.09.2013" target="_blank">10.2204/iodp.sd.15.09.2013</a>

Cited by 16 publications

References 16 publications

Climate-human-landscape interaction in the eastern foothills of Mt. Kilimanjaro (equatorial East Africa) during the last two millennia

Climate-human-landscape interaction in the eastern foothills of Mt. Kilimanjaro (equatorial East Africa) during the last two millennia

Challenges for Ice Age Dynamics: A Dynamical Systems Perspective

History of scoria‐cone eruptions on the eastern shoulder of the Kenya–Tanzania Rift revealed in the 250‐ka sediment record of Lake Chala near Mount Kilimanjaro

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