Nature Study of Hebei Rocks: 3.95-Billion-Year Trondhjemitic Gneiss Implies Early Subduction, Mantle Separation Over 4.3 Billion Years Ago
A team led by Hangqiang Xie of the Chinese Academy of Geological Sciences in Beijing reported in Nature the discovery in the Shimen Complex in Hebei province of rocks dating back 3.95 billion years, among the oldest known rocks on Earth. Earth is approximately 4.5 billion years old, and rocks from its earliest days are extremely rare. The team collected three samples for detailed analysis.
The team dated the rocks by analysing tiny zircon crystals trapped inside them. The analysis revealed that the rocks had originally formed from material that had been in contact with water at or near Earth's surface. The researchers proposed that this rapid burial was most likely achieved through a transient subduction event, suggesting that a process similar to modern-day plate tectonics may have been taking place in at least one part of Earth nearly 4 billion years ago.
Analysis of hafnium isotopes in the zircon crystals also suggested that the process of separating material from Earth's mantle to form new crust had begun more than 4.3 billion years ago. The paper is titled 'Hadean mantle depletion and 3.95-Gyr subduction implied by North China rocks', with digital object identifier 10.1038/s41586-026-11280-2.
Source: Chinese Academy of Geological Sciences
Published by GSM · USA (original Chinese edition)
Photo: 图中是香港大学许士芬地质博物馆展出的中国奥长花岗质片麻岩标本，与本研究分析的同类古老片麻岩属同一岩石类型。来源：Wikimedia Commons, File:HKU 香港大學 Stephen Hui Geological Museum 許士芬地質博物館 the oldest rocks from China TTG Migmatite Taishan complex n old trondhjemitic gneiss Baijiafen Anshan Oct 2016 Lnv.jpg, Chingo Meaopim, CC BY-SA 4.0。
