气候变化领域集成服务门户(CCPortal): On the reconciliation of biostratigraphy and strontium isotope stratigraphy of three southern Californian Plio-Pleistocene formations

CCPortal

DOI	10.1130/B35488.1
	On the reconciliation of biostratigraphy and strontium isotope stratigraphy of three southern Californian Plio-Pleistocene formations
	Buczek A.J.; Hendy A.J.W.; Hopkins M.J.; Sessa J.A.
发表日期	2020
ISSN	167606
起始页码	100
结束页码	114
卷号	133 期号:12
英文摘要	The San Diego Formation, Pico Formation, Careaga Sandstone, and Foxen Mudstone of southern California are thought to be late Pliocene to early Pleistocene; however, numerical ages have not been determined. Following assessment of diagenetic alteration via multiple methods including scanning electron microscopy (SEM), X–ray diffraction (XRD), and minor elemental concentrations, we attempted to use strontium isotope stratigraphy to assign numerical ages. Using aragonitic fossils, we obtained ages of 2.0–1.85 Ma for the Careaga Sandstone and 2.0–1.75 Ma for the uppermost Foxen Mudstone, consistent with biostratigraphic work suggesting a Gelasian age for the Careaga Sandstone. Isotope ratios for aragonitic and calcitic fossils from the Pico Formation were poorly constrained, with the exception of one bed yielding ages of 5.1–4.3 Ma. Isotope ratios from the San Diego Formation were also inconsistent within beds, with the exception of two isolated outcrops that yielded ages of 5.0–4.5 Ma and 4.5–2.8 Ma, respectively. The age estimates for the Pico and San Diego Formations are older than most ages inferred from biostratigraphy. Noting that some aragonitic specimens from the San Diego Formation yielded isotope ratios indicative of ages as old as 19.4 Ma, we propose that some outcrops have been affected by diagenesis caused by groundwater flow through proximal granitic rocks and input from detrital sediment. Although we recommend that strontium isotope results for the Pico and San Diego Formations be interpreted with caution, the ages of the uppermost Foxen Mudstone and Careaga Sandstone can be confidently placed within the early Pleistocene. © 2020 The Authors. Gold Open Access: This paper is published under the terms of the CC-BY license
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/184741
作者单位	Division of Paleontology, American Museum of Natural History, Central Park West and 79th Street, New York, New York 10024, United States; Department of Invertebrate Paleontology, Natural History Museum of Los Angeles County, 900 Exposition Blvd., Los Angeles, California 90007, United States; Department of Biodiversity, Earth and Environmental Science, Academy of Natural Sciences of Drexel University, 1900 Benjamin Franklin Parkway, Philadelphia, Pennsylvania 19103, United States
推荐引用方式 GB/T 7714	Buczek A.J.,Hendy A.J.W.,Hopkins M.J.,et al. On the reconciliation of biostratigraphy and strontium isotope stratigraphy of three southern Californian Plio-Pleistocene formations[J],2020,133(12).
APA	Buczek A.J.,Hendy A.J.W.,Hopkins M.J.,&Sessa J.A..(2020).On the reconciliation of biostratigraphy and strontium isotope stratigraphy of three southern Californian Plio-Pleistocene formations.Bulletin of the Geological Society of America,133(12).
MLA	Buczek A.J.,et al."On the reconciliation of biostratigraphy and strontium isotope stratigraphy of three southern Californian Plio-Pleistocene formations".Bulletin of the Geological Society of America 133.12(2020).