Abstract
AbstractWe use the tephrostratigraphic framework along the Aegean Volcanic Arc established in Part 1 of this contribution to determine hemipelagic sedimentation rates, calculate new tephra ages, and constrain the minimum magnitudes of (sub)plinian eruptions of the last 200 kyrs. Hemipelagic sedimentation rates range from ∼0.5 cm/kyr up to ∼40 cm/kyr and vary laterally as well as over time. Interpolation between dated tephras yields an eruption age of ∼37 ka for the Firiplaka tephra, showing that explosive volcanism on Milos is ∼24 kyrs younger than previously thought. The four marine Nisyros tephras (N1 to N4) identified in Part 1 (including the Upper (N1) and Lower (N4) Pumice) have ages of ∼57 ka, ∼63 ka, ∼69 ka, and ∼76 ka, respectively. Eruption ages for the Yali‐1 and Yali‐2 tephras are ∼55 ka and ∼34 ka, respectively. The Yali‐2 tephra comprises two geochemically and laterally distinct marine facies. The southern facies is identical to the Yali‐2 fall deposit on land but the western facies has slightly less evolved glass compositions. Overall, erupted plinian and co‐ignimbrite fall tephra volumes range from <1 to 56 km3 (excluding possible caldera fillings and ignimbrite volumes), and 80% of the eruptions had magnitude 5.5 < M ≤ 7.2 (M = log(m)‐7; m = erupted magma mass in kg). Twenty percent of the tephras represent 3.2 < M < 5.5 eruptions. The long‐term average tephra magma mass flux through highly explosive eruptions of Santorini is estimated at ∼40 kg/s. The analogous data for the Kos‐Yali‐Nisyros volcanic complex is less‐well constrained but similar to Santorini.
Highlights
Ash plumes of numerous plinian, phreatoplinian and ignimbrite-forming eruptions from calderas and stratocones of the central and eastern Aegean Volcanic Arc dispersed ash mostly eastward across the Aegean and Mediterranean seas (e.g., Keller et al, 1978)
Interpolation between dated tephras yields an eruption age of ∼37 ka for the Firiplaka tephra, showing that explosive volcanism on Milos is ∼24 kyrs younger than previously thought
From the observation that Yali-2 magma was less evolved than the Yali-1 magma, we suggest that the fast uplift of Yali sometime after the Yali-1 eruption and before the Yali-2 eruption was caused by intrusion of at least ∼2 km3 (Yali-2 erupted magma volume) of less evolved magma into a shallow crustal level
Summary
Ash plumes of numerous plinian, phreatoplinian and ignimbrite-forming eruptions from calderas and stratocones of the central and eastern Aegean Volcanic Arc dispersed ash mostly eastward across the Aegean and Mediterranean seas (e.g., Keller et al, 1978). The resulting marine ash and lapilli layers represent the major fraction of the erupted tephra volumes because the relatively small volcanic islands in the Aegean Sea provide very limited onshore depositional areas (Figure 1) Such marine tephras have previously been sampled by sediment coring across the central and eastern Mediterranean at great distances from the source volcanoes. We thereby identified 19 Pleistocene to Recent tephras from Milos, Santorini, Kolumbo, Kos, Yali and Nisyros volcanoes (Figure 1) that we could trace on the seafloor up to 300 km from their sources In this second paper, we use the correlations to well-dated onshore tephras to determine regionally variable sedimentation rates of hemipelagic sediments intercalated with the marine ash layers. We combine published tephra isopach maps, based largely on outcrops on land, with the thickness data for marine tephra layers that can be traced across
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
