Oldest-surviving crustal material from the Earth's earliest geological time period
Hadean zircon is the oldest-surviving crustal material from the Earth's earliest geological time period, the Hadean eon, about 4 billion years ago. Zircon is a mineral that is commonly used for radiometric dating because it is highly resistant to chemical changes and appears in the form of small crystals or grains in most igneous and metamorphic host rocks.[1]
Aerial photo of the Jack Hills, Australia
Hadean zircon has very low abundance around the globe because of recycling of material by plate tectonics. When the rock at the surface is buried deep in the Earth it is heated and can recrystallise or melt.[1] In the Jack Hills, Australia, scientists obtained a relatively comprehensive record of Hadean zircon crystals in contrast to other locations. The Jack Hills zircons are found in metamorphosed sediments that were initially deposited around 3 billion years ago,[1] or during the Archean Eon. However, the zircon crystals there are older than the rocks that contain them. Many investigations have been carried out to find the absolute age and properties of zircon, for example the isotope ratios, mineral inclusions, and geochemistry of zircon. The characteristics of Hadean zircons show early Earth history and the mechanism of Earth's processes in the past.[1] Based on the properties of these zircon crystals, many different geological models were proposed.
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Hadeanzircon is the oldest-surviving crustal material from the Earth's earliest geological time period, the Hadean eon, about 4 billion years ago. Zircon...
hypothesized to have occurred at the Hadean-Archean boundary. Hadean rocks are very rare, largely consisting of granular zircons from one locality (Jack Hills)...
compound crystals of zircon Baddeleyite, ZrO2 Cathodoluminescence microscope Cool Early Earth Earliest known life forms Hadeanzircon Heavy mineral sands...
date: Hadeanzircons that formed around 4.404 billion years ago. These zircons have enabled deeper research into the conditions on Earth in the Hadean eon...
in zircon geothermometry has so far been used in igneous rocks to estimate cooling temperatures of magma from zircon crystals dated to the Hadean age...
contributed nutrients to the first abiogenic steps of life on Earth. No Hadean-aged zircon grains have been identified in the Nuvvuagittuq Supracrustal Belt...
erosion or melted, are more than 4 billion years old, formed during the Hadean Eon of Earth's geological history, and mark the start of the Archean Eon...
Ma. Hadean Eon: 4031–4567.3 Ma. This term was intended originally to cover the time before any preserved rocks were deposited, although some zircon crystals...
It includes the first three of the four eons of Earth's prehistory (the Hadean, Archean and Proterozoic) and precedes the Phanerozoic eon. Major volcanic...
Harrison, T. Mark (2020), Harrison, T. Mark (ed.), "Hadean Jack Hills Zircon Geochemistry", Hadean Earth, Cham: Springer International Publishing, pp. 143–178...
sulfur-34. Evidence of life in the Late Hadean is more controversial. In 2015, biogenic carbon was detected in zircons dated to 4.1 billion years ago, but...
has a geological history dating back to 4.4 billion years ago when Hadeanzircons were formed. The earliest direct known life on land, known as stromatolites...
crustal reworking, minerals like zircon, which is difficult to melt, are preserved in the reworked rocks. Some new zircons with a younger age would be formed...
approximately 3.5 Ga. On the geologic time scale, this comprises all of the Hadean eon, starting with the formation of the Earth about 4.6 billion years ago...
Formation felsic volcanics and associated Orosirian granites. Relict Hadeanzircons (xenocrysts) in the Iwokrama Formation suggest that older crust must...
Oleg; Mojzsis, Stephen J. (May 21, 2009). "Microbial habitability of the Hadean Earth during the late heavy bombardment" (PDF). Nature. 459 (7245): 419–422...
the end of the Hadean. In addition, volcanism was severe due to the large heat flow and geothermal gradient. Nevertheless, detrital zircon crystals dated...
of the geologic record. It spans 431 million years, from the end of the Hadean Eon 4031 Mya to the start of the Paleoarchean Era 3600 Mya. The beginnings...
the Hadean and early Archean. Xenocrysts found within 3.94 Ga tonalitic gneisses of the Acasta Gneiss Complex have U–Pb dates of 4.2 Ga. These zircon xenocrysts...
crystallized in the Hadean. This block of protocrust would have been very similar to modern Iceland in its geology. With zircon U-Pb crystallization...
(or Ga) according to biologically fractionated graphite inside a single zircon grain in the Jack Hills range of Australia. The earliest evidence of life...
that the mafic host rock is also of Hadean age.[clarification needed] Significantly, the oldest detrital zircon with high correspondence to the host...
needed] The Jack Hills zircon led to an evolution in understanding of the Hadean eon. Older references generally show that Hadean Earth had a molten surface...
until the 2000s when preliminary reports of U-Pb zircon dating in the area of the belt found zircons with ages up to 3,750 Ma. Since then, the Nuvvuagittuq...
dating of 4.404 Gya zircon crystals with high δ18O values from metamorphosed quartzite of Mount Narryer in Western Australia. The Hadean atmosphere has been...
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