TY - JOUR
T1 - Emplacement of a large igneous province as a possible cause of banded iron formation 2.45 billion years ago
AU - Barley, M. E.
AU - Pickard, A. L.
AU - Sylvester, P. J.
N1 - Copyright:
Copyright 2007 Elsevier B.V., All rights reserved.
PY - 1997/1/2
Y1 - 1997/1/2
N2 - LATEST Archaean and earliest Palaeoproterozoic times (from 2.6 to 2.2 billion years ago) have generally been viewed as a largely quiescent period of Earth history; the geological record indicates the very slow deposition of pelagic and chemical sediments, and bears only a limited record of magmatic and tectonic activity. Such quiescence is consistent with the contention that the Earth's main banded iron formations (BIFs)-finely laminated chemical sedimentary rocks, rich in iron oxide-formed slowly as oxygen abundances in the oceans gradually increased, thus reducing the capacity of sea water to retain dissolved iron. Here we show that a large igneous province, comprising >30,000 km3 of dolerite, basalt and rhyolite, accompanied deposition of a Hamersley Province BIF 2,449 ± 3 million years ago. This observation indicates that Hamersley BIFs formed during a major tectono-magmatic event and were deposited very much faster than previously thought, at similar rates to (or faster than) modern pelagic sediments. Thus the largest Palaeoproterozoic BIFs, rather than simply reflecting a gradual increase in the oxygen content of the oceans during a period of tectonic quiescence, are more likely to have formed as a result of an increased supply of suboxic iron- and silica-rich sea water upwelling onto continental shelves during a pulse (or pulses) of increased submarine magmatic and hydrothermal activity.
AB - LATEST Archaean and earliest Palaeoproterozoic times (from 2.6 to 2.2 billion years ago) have generally been viewed as a largely quiescent period of Earth history; the geological record indicates the very slow deposition of pelagic and chemical sediments, and bears only a limited record of magmatic and tectonic activity. Such quiescence is consistent with the contention that the Earth's main banded iron formations (BIFs)-finely laminated chemical sedimentary rocks, rich in iron oxide-formed slowly as oxygen abundances in the oceans gradually increased, thus reducing the capacity of sea water to retain dissolved iron. Here we show that a large igneous province, comprising >30,000 km3 of dolerite, basalt and rhyolite, accompanied deposition of a Hamersley Province BIF 2,449 ± 3 million years ago. This observation indicates that Hamersley BIFs formed during a major tectono-magmatic event and were deposited very much faster than previously thought, at similar rates to (or faster than) modern pelagic sediments. Thus the largest Palaeoproterozoic BIFs, rather than simply reflecting a gradual increase in the oxygen content of the oceans during a period of tectonic quiescence, are more likely to have formed as a result of an increased supply of suboxic iron- and silica-rich sea water upwelling onto continental shelves during a pulse (or pulses) of increased submarine magmatic and hydrothermal activity.
UR - http://www.scopus.com/inward/record.url?scp=0030621144&partnerID=8YFLogxK
U2 - 10.1038/385055a0
DO - 10.1038/385055a0
M3 - Article
AN - SCOPUS:0030621144
VL - 385
SP - 55
EP - 58
JO - Nature
JF - Nature
SN - 0028-0836
IS - 6611
ER -