Earth evolution as a thermal system

Friday, 19 December 2014
Chunan Tang, DUT Dalian University of Technology, Civil Engineering, Dalian, China
After fifty years of plate-tectonic theory, the reasons why earth sometime freezed as a snowball or sometime became lethally hot resulting in mass extinction remain enigmatic. This article proposes a new hypothesis on Earth evolution. The unbalance of heat between the input and output is considered as the driving force for the Earth evolution, the lithospheric expansion and associated uplift are the triggers, the self-organized progressive failure leading to collapse of the Earth are the amplifier, and the global scale response in terms of volcanism and magmatism is the globalizer. This shallow process of lithosphere may reach a critical state with a positive feedback loop, and result in the formation of no-plume original Large Igneous Provinces (NPOLIP) in a top-down pattern. Endothermic phase changes during de-compressive melting remove heat from and cool their surroundings, including the upper parts of the lithosphere. The huge loss of Earth’s heat during eruption of LIPs, together with the endothermic cooling, may put the thermal cycle to an end and a new start of the cycle initiates. In summary, Earth drives itself to evolve in terms of thermal cycles. Global cooling and warming are the two stages of the many cycles during the Earth evolution. Glaciations are the extreme result of global cooling, whereas the LIPs, sometime accompanied with remarkable sea level dropping, are the extreme result of global warming, with a long recovering age, the interglacialstage, between them. They come and go as thermal cycle evolves, with climate warming, being caused by Earth itself rather than by external forces or human activities, as the most attractive prediction.