کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5784195 | 1638636 | 2017 | 59 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
The pre-Atlantic Hf isotope evolution of the east Laurentian continental margin: Insights from zircon in basement rocks and glacial tillites from northern New Jersey and southeastern New York
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
علوم زمین و سیارات
ژئوشیمی و پترولوژی
پیش نمایش صفحه اول مقاله
چکیده انگلیسی
This paper presents laser ablation U-Pb age and Hf isotope data for zircons from basement rocks and glacial deposits in northern New Jersey and southeastern New York. The purpose is to understand the eastern Laurentian continental margin's Hf isotope record in relation to its geologic evolution prior to the opening of the Atlantic Ocean. The basement samples encompass a Meso- to Neoproterozoic continental margin arc, an anatectic magmatic suite, as well as a Late Ordovician alkaline igneous suite emplaced during post-orogenic melting of the lithospheric mantle. Additional samples were collected from terminal moraines of two Quaternary continental ice sheets. Across the entire dataset, zircons with ages corresponding to the timing of continental margin arc magmatism (~ 1.4 Ga to ~ 1.2 Ga) have positive εHf(initial) values that define the more radiogenic end of a crustal evolution array. This array progresses towards more unradiogenic εHf(initial) values along a series of low 176Lu/177Hf (0.022 to 0.005) trajectories during subsequent anatectic magmatism (~ 1.2 Ga to ~ 1.0 Ga) and later metamorphic and metasomatic re-working (~ 1.0 Ga to ~ 0.8 Ga) of the continental margin arc crust. In contrast, nearly chondritic εHf(initial) values from the Late Ordovician alkaline magmas indicate that the Laurentian margin was underlain by a re-fertilized mantle source. Such a source may have developed by subduction enrichment of the mantle wedge beneath the continental margin during the Mesoproterozoic. Additionally, preliminary data from a metasedimentary unit of unknown provenance hints at the possibility that some of the sediments occupying this portion of the Laurentian margin prior to the Ordovician were sourced from crust older than ~ 1.9 Ga.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Lithos - Volumes 272â273, February 2017, Pages 69-83
Journal: Lithos - Volumes 272â273, February 2017, Pages 69-83
نویسندگان
N. Alex Zirakparvar, Jacob Setera, Edmond Mathez, Jill Vantongeren, Ryanna Fossum,