干旱区生态环境知识资源中心(Arid): A Rusty Record of Weathering and Groundwater Movement in the Hyperarid Central Andes

Arid

DOI	10.1029/2021GC009759
	A Rusty Record of Weathering and Groundwater Movement in the Hyperarid Central Andes
	Shaw, J. M.; Evenstar, L.; Cooper, F. J.; Adams, B. A.; Boyce, A. J.; Hofmann, F.; Farley, K. A.
通讯作者	Shaw, JM (corresponding author), Univ Bristol, Sch Earth Sci, Bristol, Avon, England.
来源期刊	GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS
EISSN	1525-2027
出版年	2021
卷号	22 期号:8
英文摘要	The Atacama Desert, on the western margin of the Central Andes, hosts some of the world's largest porphyry copper deposits (PCDs). Despite a hyperarid climate, many of these PCDs have undergone secondary supergene enrichment, whereby copper has been concentrated via groundwater-driven leaching and reprecipitation, yielding supergene profiles containing valuable records of weathering and landscape evolution. We combine hematite (U-Th-Sm)/He geochronology and oxygen isotope analysis to compare the weathering histories of two Andean PCDs and test the relative importance of climate and tectonics in controlling both enrichment and water table movement. At Cerro Colorado, in the Precordillera, hematite precipitation records prolonged weathering from similar to 31 to similar to 2 Ma, tracking water table descent following aridity-induced canyon incision from the late Miocene onward. By contrast, hematite at Spence, within the Central Depression, is mostly younger than similar to 10.5 Ma, suggesting exhumation ended much later. A heavy oxygen isotopic signature for Spence hematite suggests that upwelling formation water has been an important source of groundwater, accounting for a high modern water table despite persistent hyperaridity, whereas isotopically light hematite at Cerro Colorado formed in the presence of meteoric water. Compared with published paleo-environmental and sedimentological records, our data show that weathering can persist beneath appreciable post-exhumation cover, under hyperarid conditions unconducive to enrichment. The susceptibility of each deposit to aridity-induced water table descent, canyon incision and deep weathering has been controlled by recharge characteristics and morphotectonic setting. Erosional exhumation, rather than aridity-induced water table decay, appears to be more important for the development of supergene enrichment.
英文关键词	hematite (U-Th-Sm) He geochronology porphyry copper deposits supergene processes weathering oxygen isotope analysis Atacama Desert
类型	Article
语种	英语
开放获取类型	Green Published, Green Accepted, Green Submitted, hybrid
收录类别	SCI-E
WOS记录号	WOS:000691021600018
WOS关键词	PAMPA DEL TAMARUGAL ; PORPHYRY COPPER-DEPOSIT ; OXYGEN-ISOTOPE FRACTIONATION ; ATACAMA-DESERT ; NORTHERN CHILE ; (U-TH)/HE GEOCHRONOLOGY ; SUPERGENE ENRICHMENT ; COSMOGENIC HE-3 ; CALAMA BASIN ; AR-40/AR-39 GEOCHRONOLOGY
WOS类目	Geochemistry & Geophysics
WOS研究方向	Geochemistry & Geophysics
资源类型	期刊论文
条目标识符	http://119.78.100.177/qdio/handle/2XILL650/363378
作者单位	[Shaw, J. M.; Cooper, F. J.; Adams, B. A.] Univ Bristol, Sch Earth Sci, Bristol, Avon, England; [Evenstar, L.] Univ Brighton, Sch Environm & Technol, Brighton, E Sussex, England; [Boyce, A. J.] Scottish Univ Environm Res Ctr, E Kilbride, Lanark, Scotland; [Hofmann, F.; Farley, K. A.] CALTECH, Div Geol & Planetary Sci, Pasadena, CA 91125 USA
推荐引用方式 GB/T 7714	Shaw, J. M.,Evenstar, L.,Cooper, F. J.,et al. A Rusty Record of Weathering and Groundwater Movement in the Hyperarid Central Andes[J],2021,22(8).
APA	Shaw, J. M..,Evenstar, L..,Cooper, F. J..,Adams, B. A..,Boyce, A. J..,...&Farley, K. A..(2021).A Rusty Record of Weathering and Groundwater Movement in the Hyperarid Central Andes.GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS,22(8).
MLA	Shaw, J. M.,et al."A Rusty Record of Weathering and Groundwater Movement in the Hyperarid Central Andes".GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS 22.8(2021).