DOI: 10.1016/j.epsl.2018.01.019
Scopus记录号: 2-s2.0-85044328547
论文题名: Role of upper-most crustal composition in the evolution of the Precambrian ocean–atmosphere system
作者: Large R.R. ; Mukherjee I. ; Zhukova I. ; Corkrey R. ; Stepanov A. ; Danyushevsky L.V.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2018
卷: 487 起始页码: 44
结束页码: 53
语种: 英语
英文关键词: boring billion
; K–U–Th granites
; micro nutrients
; Proterozoic
; REE
; UMCC
Scopus关键词: Atmospheric chemistry
; Boring
; Drops
; Exploratory geochemistry
; Geochemistry
; Geochronology
; Granite
; Magnesite
; Manganese
; Matrix algebra
; Nutrients
; Oceanography
; Oil shale
; Pyrites
; Rocks
; Shale
; Trace elements
; Uranium
; Banded iron formations
; Carbonate equilibriums
; Complex relationships
; Hydrothermal activity
; Large Igneous Provinces (LIPs)
; Proterozoic
; Trace element concentrations
; UMCC
; Upper atmosphere
; atmosphere-ocean system
; banded iron formation
; black shale
; chemical composition
; continental crust
; granite
; hydrothermal activity
; large igneous province
; Precambrian
; rare earth element
; sediment chemistry
; trace element
; upper crust
英文摘要: Recent research has emphasized the potential relationships between supercontinent cycles, mountain building, nutrient flux, ocean–atmosphere chemistry and the origin of life. The composition of the Upper-Most Continental Crust (UMCC) also figures prominently in these relationships, and yet little detailed data on each component of this complex relationship has been available for assessment. Here we provide a new set of data on the trace element concentrations, including the Rare Earth Elements (REE), in the matrix of 52 marine black shale formations spread globally through the Archean and Proterozoic. The data support previous studies on the temporal geochemistry of shales, but with some important differences. Results indicate a change in provenance of the black shales (upper-most crustal composition), from more mafic in the Archean prior to 2700 Ma, to more felsic from 2700 to 2200 Ma, followed by a return to mafic compositions from 2200 to 1850 Ma. Around 1850 to 1800 Ma there is a rapid change to uniform felsic compositions, which remained for a billion years to 800 Ma. The shale matrix geochemistry supports the assertion that the average upper-most continental source rocks for the shales changed from a mix of felsic, mafic and ultramafic prior to 2700 Ma to more felsic after 1850 Ma, with an extended transition period between. The return to more mafic UMCC from 2200 to 1850 Ma is supported by the frequency of Large Igneous Provinces (LIPs) and banded iron formations, which suggest a peak in major mantle-connected plume events and associated Fe-rich hydrothermal activity over this period. Support for the change to felsic UMCC around 1850 Ma is provided by previous geological data which shows that felsic magmas, including, A-type granites and K–Th–U-rich granites intruded vast areas of the continental crust, peaking around 1850 Ma and declining to 1000 Ma. The implications of this change in UMCC are far reaching and may go some way to explain the distinct features of the Boring Billion (1800–800 Ma). Firstly, because mafic–ultramafic rocks contain significantly higher levels of the bio-essential nutrient elements (e.g. Fe, P, Ni, Cr, Co, Cu, Se, Mn, Zn) compared with felsic rocks, the flux of macro- and micro-nutrients to the ocean would have decreased significantly post 1850 Ma. This would have contributed to a drop in productivity and a drop in atmosphere O2 as suggested by the marine pyrite proxy. In addition, a change from mafic to felsic dominant composition of the UMCC post 1850 Ma, would have led to a decrease in the erosive flux of Ca and Mg to the ocean, affecting the oceanic carbonate equilibrium and likely contributing to a rise in atmosphere CO2. On this basis, we speculate that the commencement of the middle Proterozoic, commonly known as the Boring Billion period from 1800 to 800 Ma, marks the start of an extended time in Earth's evolution when the UMCC became dominated by felsic rocks, particularly K–U–Th–anorogenic granites. This led to a period of anomalously low concentrations of bio-essential trace elements, but elevated REE, U, Th, Pb, Tl, Rb/Al and K/Na in the oceans. © 2018 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/110016
Appears in Collections: 影响、适应和脆弱性 气候变化事实与影响
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作者单位: CODES, ARC Centre of Excellence in Ore Deposits, University of Tasmania, Hobart, Tasmania, Australia; Tasmania Institute of Agriculture, University of Tasmania, Hobart, Tasmania, Australia
Recommended Citation:
Large R.R.,Mukherjee I.,Zhukova I.,et al. Role of upper-most crustal composition in the evolution of the Precambrian ocean–atmosphere system[J]. Earth and Planetary Science Letters,2018-01-01,487