Petrology of a Late Archaean, Highly Potassic, Sanukitoid Pluton from the Baltic Shield: Insights into Late Archaean Mantle Metasomatism
نویسندگان
چکیده
منابع مشابه
Pervasive oxygenation along late Archaean ocean margins
The photosynthetic production of oxygen in the oceans is thought to have begun by 2.7 billion years ago, several hundred million years before appreciable accumulation of oxygen in the atmosphere. However, the abundance and distribution of dissolved oxygen in the late Archaean oceans is poorly constrained. Here we present geochemical profiles from 2.6to 2.5-billion-year-old black shales from the...
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Geochemical characteristics of greywacke and intercalated phyllites from Haveri and Dharwad block (long N 75° 10' to 75° 25' E and lat 15° 30' to 45° 00'S and (long 75° 05'E and lat S 15° 15' to 15° 35') of Shimoga basin have been studied to unravel the provenance and the tectonic setting of the greywackes. The greywackes are medium grained feldspatholithic and show presence of perthitic feldsp...
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The development of the multi-collector ICP-MS has provided a wider range of isotopic systems (e.g. Li, Mg, Fe, Cu, Hf, Tl) that can used to place constraints on the timing of mantle metasomatism and better characterize metasomatic processes. Associated with the application of these isotopic systems has been the parallel development of in-situ isotope analysis using a laser ablation microprobe a...
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Evidence for the existence of life during the Archaean segment of Earth history (more than 2500 Myr ago) is summarized. Data are presented for 48 Archaean deposits reported to contain biogenic stromatolites, for 14 such units reported to contain 40 morphotypes of putative microfossils, and for 13 especially ancient, 3200-3500 Myr old geologic units for which available organic geochemical data a...
متن کاملCooling of the Earth in the Archaean: Consequences of pressure-release melting in a hotter mantle
A model is presented to describe the cooling of the Earth in the Archaean. At the higher Archaean mantle temperatures pressure-release melting starts deeper and generates a thicker basaltic or komatiitic crust and depleted harzburgite layer compared with the present-day situation. Intrinsic compositional stability and lack of mechanical coherency renders the mechanism of plate tectonics ineffec...
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ژورنال
عنوان ژورنال: Journal of Petrology
سال: 2008
ISSN: 0022-3530,1460-2415
DOI: 10.1093/petrology/egm084