气候变化领域集成服务门户(CCPortal): Detrital zircon double-dating of forearc basin strata reveals magmatic, exhumational, and thermal history of sediment source areas

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DOI	10.1130/B35043.1
	Detrital zircon double-dating of forearc basin strata reveals magmatic, exhumational, and thermal history of sediment source areas
	Enkelmann E.; Lohff S.K.S.; Finzel E.S.
发表日期	2019
ISSN	167606
起始页码	1364
结束页码	1384
卷号	131 期号:2021-07-08
英文摘要	Subduction along the southern margin of Alaska, USA, has been ongoing since at least the Jurassic. However, the character of the subducting slab has changed through time and has included subduction of normal oceanic crust, a spreading ridge, and an oceanic plateau. The latter two resulted in a change of subduction mode by inducing a shallow subduction angle. Geologic processes and landscape evolution of the overriding plate were affected by these variations in subduction mode and are recorded in the forearc basin strata. We investigate the Cenozoic to modern sediment of the forearc Cook Inlet basin in south-central Alaska. Here we use a double-dating approach that combines fission track dating and U-Pb dating on individual detrital zircon grains. In total we analyzed more than 1700 zircons from Eocene to Pliocene strata and modern river sand that has eroded from the surrounding regions of the Cook Inlet basin. The doubledating approach combined with the existing knowledge of the regional geology allows us to discriminate between magmatic cooled grains of extrusive and shallow intrusive rocks, exhumational cooled grains, and thermal reset grains. We find that the erosion of both shallow and deep intrusive arc rocks dominate the detrital age signal, while syn-depositional extrusive grains are lacking. The erosion of rocks that have been thermally altered during the subduction of a spreading ridge dominates the fission track (FT) age signal. This pattern is particularly prominent in the accretionary prism where ages in the most inboard (older) portion have not been thermally reset, but ther- mal resetting is prevalent in the outboard (younger) portion located proximal to the Paleocene-Eocene near-trench intrusions. Thermal alteration is also evident in the region of the arc that was affected by the passage of the asthenospheric slab window. The erosional signal of the more inboard arc and backarc region (Alaska Range) is characterized by exhumational FT ages of deep-seated rocks, which currently provide material into the forearc basin. This age signal results from flat-slab subduction of the Yakutat microplate, which transfers stress far inboard and produces significant mountain building and deformation. This exhumational age signal, however, is not recorded in the late Cenozoic strata, suggesting that the modern landscape developed since < 3 Ma. © 2019 Geological Society of America.
语种	英语
来源期刊	Bulletin of the Geological Society of America
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/184954
作者单位	University of Calgary, Department of Geoscience, 2500 University Drive NW, Calgary, AB T2N 1N4, Canada; University of Cincinnati, Department of Geology, 500 Geology Physics Building, Cincinnati, OH 45221-0013, United States; University of Iowa, Department of Earth and Environmental Science, 115 Trowbridge Hall, Iowa City, IA 52242, United States
推荐引用方式 GB/T 7714	Enkelmann E.,Lohff S.K.S.,Finzel E.S.. Detrital zircon double-dating of forearc basin strata reveals magmatic, exhumational, and thermal history of sediment source areas[J],2019,131(2021-07-08).
APA	Enkelmann E.,Lohff S.K.S.,&Finzel E.S..(2019).Detrital zircon double-dating of forearc basin strata reveals magmatic, exhumational, and thermal history of sediment source areas.Bulletin of the Geological Society of America,131(2021-07-08).
MLA	Enkelmann E.,et al."Detrital zircon double-dating of forearc basin strata reveals magmatic, exhumational, and thermal history of sediment source areas".Bulletin of the Geological Society of America 131.2021-07-08(2019).