干旱区生态环境知识资源中心(Arid): Subtle signatures of seeps: Record of groundwater in a Dryland, DK, Olduvai Gorge, Tanzania

Arid

DOI	10.1002/dep2.11
	Subtle signatures of seeps: Record of groundwater in a Dryland, DK, Olduvai Gorge, Tanzania
	Ashley, Gail M.; de Wet, Carol B.; Barboni, Doris; Magill, Clayton R.
通讯作者	Ashley, GM
来源期刊	DEPOSITIONAL RECORD
ISSN	2055-4877
出版年	2016
卷号	2 期号:1 页码:4-21
英文摘要	Few proxies exist to identify aridity in the depositional record, although drylands cover ca 30% of the modern continental surface. New exposures in a siliciclastic and carbonate sequence in an arid to hyperarid basin at Olduvai Gorge, Tanzania provide a unique multi-proxy record of a 185Ma landscape that was exploited by early humans. The 2m thick sequence of clastics and carbonates that are exposed along a 450m outcrop records climate change over a single precession (dry-wet-dry) cycle. Siliciclastic data (sedimentary structures, grain size, mineralogy) and biological data are combined with data for a 10 to 35cm thick limestone (stable isotopes, elemental geochemistry, petrography) to generate a depositional facies model for a site DK (Douglass Korongo) on this dry rift basin landscape. This site was situated on a low gradient, distal portion of a volcaniclastic alluvial fan. The clastics are intercalated distal alluvial fan sandy silts and lake clays that accumulated in a low energy environment. Groundwater discharge and the alkaline springs and seeps during wet-to-dry change in climate made a freshwater carbonate-rich environment. Bedded lithofacies (a lime mudstone with fossils) were deposited in shallow standing (spring-fed) pools, while nodular lithofacies with calcite spherulites indicate permanently saturated ground (seeps). Both environments experienced similar diagenesis, that is, the precipitation of authigenic barite from supersaturated groundwater, desiccation and pedogenesis, and late-stage calcite precipitation. Compositional and isotopic data suggest that a fresh groundwater-fed system was available to early humans even during dry intervals of the precession cycle.
英文关键词	Barite groundwater limestone olduvai volcaniclastic
类型	Article
语种	英语
开放获取类型	DOAJ Gold, Green Published
收录类别	ESCI
WOS记录号	WOS:000379149800001
WOS关键词	LOWERMOST BED-II ; HOMINID LAND-USE ; ARID RIFT BASIN ; EAST-AFRICA ; PALEOCLIMATE RECORD ; CLIMATE-CHANGE ; CLAY-MINERALS ; KENYA RIFT ; FLK NORTH ; LAKE
WOS类目	Geology
WOS研究方向	Geology
资源类型	期刊论文
条目标识符	http://119.78.100.177/qdio/handle/2XILL650/331562
作者单位	[Ashley, Gail M.] Rutgers State Univ, Earth & Planetary Sci, Piscataway, NJ 08854 USA; [de Wet, Carol B.] Franklin & Marshall Coll, Earth & Environm, Lancaster, PA 17604 USA; [Barboni, Doris] Aix Marseille Univ, CNRS IRD UM CEREGE 34, Technopole Environm Arbois Mediterranee,BP80, F-13545 Aix En Provence, France; [Magill, Clayton R.] Swiss Fed Inst Technol, Geol Inst, Biogeosci, Zurich, Switzerland
推荐引用方式 GB/T 7714	Ashley, Gail M.,de Wet, Carol B.,Barboni, Doris,et al. Subtle signatures of seeps: Record of groundwater in a Dryland, DK, Olduvai Gorge, Tanzania[J],2016,2(1):4-21.
APA	Ashley, Gail M.,de Wet, Carol B.,Barboni, Doris,&Magill, Clayton R..(2016).Subtle signatures of seeps: Record of groundwater in a Dryland, DK, Olduvai Gorge, Tanzania.DEPOSITIONAL RECORD,2(1),4-21.
MLA	Ashley, Gail M.,et al."Subtle signatures of seeps: Record of groundwater in a Dryland, DK, Olduvai Gorge, Tanzania".DEPOSITIONAL RECORD 2.1(2016):4-21.