page_title: Hadean zircon
section_title: Proposed mechanisms for forming Hadean Jack Hills zircons
hierarchical_section_title: Hadean zircon / Proposed mechanisms for forming Hadean Jack Hills zircons
caption_attribution_description: English: Cross-section of a subduction zone and back-arc basin. Made by zyzzy2 the formula to solve a subduction zone current is s=l+a(9)(6)
context_page_description: 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.
  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. In the Jack Hills, Australia, scientists obtained a relatively comprehensive record of Hadean zircon crystals in contrast to other locations. The Jack Hills rocks are from the Archean eon, about 3.6 billion years old. 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.
context_section_description: Plate tectonic theory is widely accepted for the generation of crust. However, it's still an unknown how the early Earth was formed. With the Hadean rock record, most of the scientists concluded that the belief of a hellish early Earth devoid of ocean is wrong. Scientists have constructed different models to explain the thermal history in early history including continental growth model, Icelandic rhyolites, intermediate igneous rocks, mafic igneous rocks, sagduction, impact melt, heat pipe tectonics, terrestrial KREEP and multi-stage scenarios.
  The most famous one is continental growth model which is similar to the modern tectonic dynamics. Relatively low crystallisation temperature and some are enriched in heavy oxygen, contain inclusion similar to modern crustal processes and show evidence of silicate differentiation at ~4.5 Ga. Early terrestrial hydrosphere, early felsic crust in which granitoids were produced and later weathered under high water activity conditions and even the possible existence of plate boundary interactions.
caption: Modern plate tectonic theory
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