干旱区生态环境知识资源中心(Arid): Rock varnish record of the African Humid Period in the Lake Turkana basin of East Africa

Arid

DOI	10.1177/09596836211011655
	Rock varnish record of the African Humid Period in the Lake Turkana basin of East Africa
	Liu, Tanzhuo; Lepre, Christopher J.; Hemming, Sidney R.; Broecker, Wallace S.
通讯作者	Liu, TZ (corresponding author), Columbia Univ, Lamont Doherty Earth Observ, 61 Route 9W, Palisades, NY 10964 USA.
来源期刊	HOLOCENE
ISSN	0959-6836
EISSN	1477-0911
出版年	2021
卷号	31 期号:8 页码:1239-1249
英文摘要	Rock varnish is a manganiferous dark coating accreted on subaerially exposed rocks in drylands. It often contains a layered microstratigraphy that records past wetness variations. Varnish samples from latest Pleistocene and Holocene geomorphic features in the Lake Turkana basin, East Africa display a regionally replicable microstratigraphy record of Holocene millennial-scale wetness variability and a broad interval of wetter conditions during the African Humid Period (AHP). Three major wet pulses in the varnish record occurred during the generally wet interval of the early Holocene (11.5-8.5 ka) when the lake attained its maximum high stand (MHS) at 455-460 m. A >23 m drop from the MHS occurred between 8.5 and 8 ka. Subsequently two additional wet pulses occurred during the early to middle Holocene (8-5 ka) when the lake occupied its secondary high stand at 445 m. Collectively, these five wet phases represent an extended wet interval coincident with the AHP in the region. One moderate wet phase occurred during the subsequent climatic transition from the humid to arid regime (5-4.3 ka) after the lake level dropped rapidly from 445 m to <405 m. Five minor wet phases took place during the overall arid period of the late Holocene (4.3-0 ka) when the lake level oscillated below 405 m. These findings indicate that the AHP terminated rapidly around 5 ka in the Turkana basin in terms of lake level drop, but the regional shift in relative humidity from the AHP mode to its present-day condition lagged for about 700 years until 4.3 ka, hinting at a gradual phasing out in terms of moisture condition. These findings further suggest that Lake Turkana overflowed intermittently into the Nile drainage system through its topographic sill at 455-460 m during the early Holocene and has become a closed-basin lake thereafter for the past 8 ky.
英文关键词	African monsoon desert varnish Holocene climate variability microstratigraphy millennial-scale wet event shoreline fluctuation
类型	Article
语种	英语
收录类别	SCI-E
WOS记录号	WOS:000646343500001
WOS类目	Geography, Physical ; Geosciences, Multidisciplinary
WOS研究方向	Physical Geography ; Geology
资源类型	期刊论文
条目标识符	http://119.78.100.177/qdio/handle/2XILL650/350476
作者单位	[Liu, Tanzhuo; Lepre, Christopher J.; Hemming, Sidney R.; Broecker, Wallace S.] Columbia Univ, Lamont Doherty Earth Observ, 61 Route 9W, Palisades, NY 10964 USA; [Lepre, Christopher J.] Rutgers State Univ, Dept Earth & Planetary Sci, New Brunswick, NJ USA
推荐引用方式 GB/T 7714	Liu, Tanzhuo,Lepre, Christopher J.,Hemming, Sidney R.,et al. Rock varnish record of the African Humid Period in the Lake Turkana basin of East Africa[J],2021,31(8):1239-1249.
APA	Liu, Tanzhuo,Lepre, Christopher J.,Hemming, Sidney R.,&Broecker, Wallace S..(2021).Rock varnish record of the African Humid Period in the Lake Turkana basin of East Africa.HOLOCENE,31(8),1239-1249.
MLA	Liu, Tanzhuo,et al."Rock varnish record of the African Humid Period in the Lake Turkana basin of East Africa".HOLOCENE 31.8(2021):1239-1249.