DOI: 10.1016/j.epsl.2017.10.033
Scopus记录号: 2-s2.0-85033596784
论文题名: Lithospheric discontinuities beneath the U.S. Midcontinent – signatures of Proterozoic terrane accretion and failed rifting
作者: Chen C. ; Gilbert H. ; Fischer K.M. ; Andronicos C.L. ; Pavlis G.L. ; Hamburger M.W. ; Marshak S. ; Larson T. ; Yang X.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2018
卷: 481 起始页码: 223
结束页码: 235
语种: 英语
英文关键词: lithosphere–asthenosphere boundary
; mid-lithospheric discontinuity
; Reelfoot Rift
; Sp receiver function
; terrane accretion
; U.S. Midcontinent
Scopus关键词: Chemical modification
; Seismology
; Shear flow
; Shear waves
; Structural geology
; Lithospheric
; Receiver functions
; Reelfoot Rift
; Terrane accretion
; U.S. Midcontinent
; Tectonics
; accretion
; asthenosphere
; igneous intrusion
; lithospheric structure
; Moho
; rifting
; seismic survey
; terrane
; three-dimensional modeling
; Illinois
; Indiana
; Kentucky
; Ozark Mountains
; Reelfoot Rift
; United States
英文摘要: Seismic discontinuities between the Moho and the inferred lithosphere–asthenosphere boundary (LAB) are known as mid-lithospheric discontinuities (MLDs) and have been ascribed to a variety of phenomena that are critical to understanding lithospheric growth and evolution. In this study, we used S-to-P converted waves recorded by the USArray Transportable Array and the OIINK (Ozarks–Illinois–Indiana–Kentucky) Flexible Array to investigate lithospheric structure beneath the central U.S. This region, a portion of North America's cratonic platform, provides an opportunity to explore how terrane accretion, cratonization, and subsequent rifting may have influenced lithospheric structure. The 3D common conversion point (CCP) volume produced by stacking back-projected Sp receiver functions reveals a general absence of negative converted phases at the depths of the LAB across much of the central U.S. This observation suggests a gradual velocity decrease between the lithosphere and asthenosphere. Within the lithosphere, the CCP stacks display negative arrivals at depths between 65 km and 125 km. We interpret these as MLDs resulting from the top of a layer of crystallized melts (sill-like igneous intrusions) or otherwise chemically modified lithosphere that is enriched in water and/or hydrous minerals. Chemical modification in this manner would cause a weak layer in the lithosphere that marks the MLDs. The depth and amplitude of negative MLD phases vary significantly both within and between the physiographic provinces of the midcontinent. Double, or overlapping, MLDs can be seen along Precambrian terrane boundaries and appear to result from stacked or imbricated lithospheric blocks. A prominent negative Sp phase can be clearly identified at 80 km depth within the Reelfoot Rift. This arrival aligns with the top of a zone of low shear-wave velocities, which suggests that it marks an unusually shallow seismic LAB for the midcontinent. This boundary would correspond to the top of a region of mechanically and chemically rejuvenated mantle that was likely emplaced during late Precambrian/early Cambrian rifting. These observations suggest that the lithospheric structure beneath the Reelfoot Rift may be an example of a global phenomenon in which MLDs act as weak zones that facilitate the removal of cratonic lithosphere that lies beneath. © 2017 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/110165
Appears in Collections: 影响、适应和脆弱性 气候变化事实与影响
There are no files associated with this item.
作者单位: Department of Earth, Atmospheric, and Planetary Sciences, Purdue University, West Lafayette, IN 47907, United States; Department of Geoscience, University of CalgaryAlberta T2N 1N4, Canada; Department of Geological Sciences, Brown University, Providence, RI 02912, United States; Department of Earth and Atmospheric Sciences, Indiana University, Bloomington, IN 47405, United States; School of Earth, Society, and Environment, University of Illinois at Urbana-Champaign, Champaign, IL 61820, United States; Illinois State Geological Survey, Champaign, IL 61820, United States; Department of Geosciences, University of Massachusetts, Amherst, MA 01003, United States
Recommended Citation:
Chen C.,Gilbert H.,Fischer K.M.,et al. Lithospheric discontinuities beneath the U.S. Midcontinent – signatures of Proterozoic terrane accretion and failed rifting[J]. Earth and Planetary Science Letters,2018-01-01,481