Sedimentary rocks from the barberton greenstone

The superbly exposed units are probably unique worldwide in allowing the detailed analysis and interpretation of micro-scale and high-resolution Archean analytical data in regional and temporal context. Reasons to drill Most outcrops in the Barberton Greenstone Belt, despite appearing fresh, have been affected by oxidative weathering, the effects of surface - or near-surface - organisms e. Geochemical work on the short and usually stratigraphically poorly located drill core provided by the mining industry is commonly compromised by hydrothermal alteration.

Sedimentary rocks from the barberton greenstone

Other Info In the beginning: Making Earth a habitable planet Even natural scientists would agree — but they would be keen to add that there was more to it and point to the mountains behind Barberton!

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After Earth had formed about 4, million years ago from collisions of innumerable small rocky bodies, the embryonic Earth was a initially a hot and inhospitable place but it may have cooled quickly. From the first Million years of its history, the Hadean, we have no record left, only a few tiny minerals.

The mountains are made by geological strata world-famous for their staggering age of about 3, to more than 3, Million years. That makes them, together with similar rocks in northwest Australia, the oldest well-preserved rocks on Earth. Even though the strata in the Barberton Mountains are all crumpled at km-scale and displaced against each other by geological faults, scientists congregate here yearly to painstakenly take the rocks apart and to study them in the field and in laboratories.

The mountains harbor information about its atmosphere, the oceans, climate, volcanism, meteorite impacts, and the physical environment in which the first microscopic life forms successfully established themselves and then spread out to conquer the planet.

The geotrail along the paved R40 road which winds its way across the high mountains to the Swazi border makes it possible to comfortably learn about these rocks and enjoy the scenery responsibly.

Numerous colourful and well-designed information tablets at lay-bys along the road inform about landscape, nature, and the stories the rocks have to tell. The Barberton Greenstone Belt is built up of three major rock units: The Onverwacht Group is at about 3, to 3, million years old.

It consists mostly of dark green and black former lava flows stacked on top of each other many kilometres thick, some of the hottest lava ever to have flowed on the face of the planet.

Yet between the lava flows exist seams and beds of black former deep-sea sediment which contains microscopic remnants of life that must have floated in the oceans even back then.

The Fig Tree Group, ca.

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Some of them were mined in small surface operations. Because some of these sediments were made from molecules in the ocean water, the Fig Tree Group is famous for the information it provides about the composition and temperature of the earliest oceans.

This rock unit also contains, in places, strata formed by large meteorite impacts.

Sedimentary rocks from the barberton greenstone

Banded-iron formation, probably a deposit originally made of bacteria: Sediments of the Moodies Group were probably deposited within only a few Million years, much more quickly than the other strata, and are dated to be about 3, million years old. The strata consist mainly of sandstones which are rich in quartz grains and which were laid down along ancient coastal plains and shorelines.Groups, Barberton greenstone belt, South Africa, inferred by However, many of the sedimentary rocks are cherts composed largely of silica with trace amounts of carbonaceous material, and they lack metamorphic mineral assemblages that might record their thermal histories.

The. Greenstone belts are primarily formed of volcanic rocks, dominated by basalt, with minor sedimentary rocks inter-leaving the volcanic formations. Through time, the degree of sediment contained within greenstone belts has risen, and the amount of ultramafic rock (either as layered intrusions or as volcanic komatiite) has decreased.

Greenstone belts are geographical zones that are made up of metamorphosed sedimentary and volcanic rocks that are commonly found in continental shields. Greenstone belts are characterized by varying sequences of volcanic and sedimentary rocks. barberton green-sto ne belt THE Barberton Greenstone Belt occurs in an area known as the Barberton Mountain Land - a rugged tract of country in the Lowveld region of .

A gold mine. Hydrothermal, fault/shear-hosted zones of mineralisation in the Archean meta-sedimentary rocks of the Barberton Greenstone Belt. One of 4 mines that produced 70% of the gold found in this area with the remaining 30% coming from additional gold deposits.

Sedimentary rocks from the barberton greenstone

The Geotrail: The Barberton Greenstone Belt is built up of three major rock units: The Onverwacht Group, followed by Fig Tree and Moodies Group. The Onverwacht Group .

Barberton Geology