Considered for almost 50 years the oldest rock on Earth, the Acasta Gneiss – a tonalite gneiss found in the Slave craton in the NWT of Canada – indeed includes some of the oldest known rocks of continental crust on Earth, dated at approximately 4.03 billion years, with Earth’s age being 4.543 billion-years.
However, only last year a study confirmed that the Nuvvuagittuq Greenstone Belt in Quebec is older, dating to over 4.16 billion years. It includes the oldest rocks representing a basaltic oceanic crust
Also the bedrock of Greenland is pretty old. The photo shows a 3.3-billion-year-old shear zone with felsic migmatites and dark gneiss on the island of Tunertoq (
from William E. Glassley (2018): A Wilder Time: Notes from a Geologist at the Edge of the Greenland Ice).The Great Dyke of Zimbabwe is a layered mafic intrusion of igneous, metal-bearing rock that has been dated to approximately 2.5 billion years. The dyke (or dike in American English) intrudes through the even older rocks of African craton, the core of oldest rocks forming the continent of Africa (
by NASA)The oldest rocks of South America are found in the São Francisco Craton, located in southeastern Brazil. and dates to 3.4 billion years. The Patos shear zone in the states of Paraiba and Ceará is far younger, dating to the Cryogenian (over 600 million years old) and reactivated during the Cretaceous, when South America and Africa formed a single land mass. However, this tens of kilometres wide and hundreds of kilometres long shear zone is an outstanding example of crustal-scale shear zones with tectonic structures ranging from the grain scale to tens of kilometres (
by IUGS).
by IUGS).3.6-billion-year-old colourful Banded-Iron-Formations found in the Pilbara desert in northwestern Australia predate atmospheric oxygen. Some models explain the layered structure as microbial mats, others as periodic deposition of quartz and iron-oxide layers due to variations in oxygen levels of the early oceans.
‘Egg-carton’ shaped sedimentary structures from the 3.6 to 2.5-billion-year-old Dharwar Craton, India, are also explained as stromatolites or layered microbial mats ( by Shukla, Y., Sharma, M. ‘Egg-carton’ shaped plausible organo-sedimentary structures from the Archaean Dharwar Craton, India. Int J Earth Sci (Geol Rundsch) 109, 931–932 (2020).
by Shukla, Y., Sharma, M. ‘Egg-carton’ shaped plausible organo-sedimentary structures from the Archaean Dharwar Craton, India. Int J Earth Sci (Geol Rundsch) 109, 931–932 (2020).Rapakivi-textured granite with K-feldspar ovoids (pink) surrounded by white plagioclase rims featured on a stamp of Finland. The distinctive and visually appealing nature of rapakivi granite has led to its widespread use as dimension stone. Rapakivi granites span most of Earth’s history, but the classic Rapakivi granite from Scandinavia hails primarily from the Proterozoic (1.5 billion years), associated with volcanism and magmatic intrusions during the breakup of the supercontinent Nuna. The oldest (similar) rocks are found in he Russian portions of the Baltic Shield, including a variety of granitic rocks dating to 3.5 billion years.
The 3.8-billion-year-old Baberton Greenstone Belt in South Africa preserves structures resembling hydrothermal veins. Together with small vesicles – interpreted as gas bubbles produced by microbes – some researchers argue that this rock hosted some are the earliest examples of microbial communities known from the fossil record ( by https://www.science.org/doi/10.1126/sciadv.abf3963).
by https://www.science.org/doi/10.1126/sciadv.abf3963).The oldest rocks in Antarctica are found in the Napier Complex, a rock succession displaying a colorful variety of high-grade metamorphic minerals. This metamorphism likely happened already in Archean times over 2.5 billion years ago, with the protoliths being likely magma-like rocks formed at least 3.8 billion years ago ( by https://www.bedrockpodcast.com/all-episodes/miniseries-antarctica)
by https://www.bedrockpodcast.com/all-episodes/miniseries-antarctica)