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different parts of the desert world. The aim once again is to be illustrative rather than
encyclopaedic.
14.3 Speleothem studies from the desert world
14.3.1 Speleothem studies from peninsular Arabia
We saw in Section 14.2 that increased precipitation in the past was reflected in more
active formation of speleothems. Fleitmann et al. ( 2003a ; 2003b ; 2007 ; 2011 ;and
Fleitmann and Matter, 2009 ) have analysed the oxygen isotopes and fluid inclusions
preserved within speleothems from northern Oman and southern Yemen to obtain a
record of past wet phases extending back to 330 ka. At Hoti Cave in northern Oman,
they found that speleothem deposition was rapid at 6.3-10.5, 78-82, 120-130, 180-
200 and 300-330 ka (Fleitmann et al., 2003a ; Fleitmann and Matter, 2009 ). Analysis
of the D/H ratios (
18 O values indicated that speleothem deposition
coincided with interglacial or interstadial conditions during which groundwater was
primarily recharged frommoisture derived from a southern source (the Indian Ocean),
at a time when the monsoon rainfall belt extended further north and reached northern
Oman. Later work on Mukalla Cave in southern Yemen demonstrated that, just as
at Hoti Cave in Oman, speleothems grew only during peak interglacial phases such
as Marine Isotope Stages (MIS) 1 (early to mid-Holocene), 5a, 5c, 5e, 7a, 7e and 9,
with the highest precipitation over that time span coinciding with the last interglacial
(MIS 5e) and the lowest occurring during the early to mid-Holocene (Fleitmann et al.,
2011 ). These ages are consistent with ages obtained from four generations of lake
deposits in southern Arabia dating to approximately 125 ka, 100 ka, 80 ka and early
Holocene (Rosenberg et al., 2011 ), incidentally also providing circumstantial support
for the notion of multiple dispersals of humans from Africa across southern Arabia.
Aridity prevailed in southern Arabia between around 75 ka and 10.5 ka, creating a
desert barrier for human movement at that time.
Although the speleothem record frompeninsular Arabia can document past changes
in climate, especially precipitation, it cannot explain the wider causes of such changes.
To do this, we need additional lines of evidence. Marine sediment cores from the north-
eastern Arabian Sea have shown that laminated bands rich in organic carbon reflect
strong, monsoon-induced biological productivity and coincide with relatively warm
interstadial events evident in North Atlantic marine sediment cores, as well as in
Greenland ice cores, where they are well-known as the Dansgaard-Oeschger warm
interstadial events (Schulz et al., 1998 ). Conversely, during periods when the south-
west monsoon was less active, bioturbated bands low in organic carbon accumulated in
the Arabian Sea and were synchronous with colder, high-latitude events and associated
pulses of meltwater discharge into the North Atlantic, known as Heinrich events. There
thus appears to be a correlation between high-latitude temperature changes, variations
D )andthe
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