The present day human understanding of the Earth is still superficial, and the issue of geodynamics is still exploratory both foreign or domestically. The 10th major scientific question, out of total of 125, identified by the Science magazine in 2005 was “How does the Earths interior work”, noting that the source of the earths driving force had not yet been resolved. The book, “Chinese disciplinary Developmental strategy-Plate Tectonics and continental Dynamics” published in 2017, believed that although the plate tectonics theory has achieved great success, the theory still has three major inherent problems, namely the plate driving force, plate origin and plate theory when applied to continents. Among them, the driving mechanism of plate motion is the most important and urgent problem to be solved.
The seminar is divided into two parts: reporting of main views, and discussion of the controversy. In the reporting section, five speakers expound their views on the driving force mechanism. Liang Guanghe puts forward a new theory of continental drift. Through analyses of a wealth of data, he believes that there are many problems in the traditional model of seafloor spreading being the driving force. He cites many geological and geophysical observations that the persistent driving force for continental drift is not the sustained seafloor spreading but continuous magma upwelling behind and beneath the continental plate in a spontaneous chain reaction. Wan Tianfeng proposes a new driving mode based on meteorite impact theory, believing that the traditional seafloor spreading conveyor model cannot explain why the continental drift speed is much larger than the mantle convection velocity. He hypothesizes that the meteorite impact induces mantle diapirs to promote continental plate movement. Tang Chunan puts forth an Earth cracking theory. He believes that the accumulation and release of thermal energy inside the Earth make the lithospheric mantle going through alternating hot and cold cycles in the geological history. According to Mao Xiaopings analysis, only the circumferential-direction stress is strong enough to be the proposed earth driving force that promotes the plate motion, that the circumferential-direction stress is released at the weak point of the lithosphere to promote the relative movement of the crust, and that the long time unexplained “crustal abnormal pressure” is in fact circumferential-direction stress, but the tectonic force and collision force that can be independent of gravity do not exist.
During discussion and contention, everyone is free to speak on the driving force of crustal movement. Liang Guanghe acknowledges that the meteorite impact proposed by Wan Tianfeng may better explain the initial driving force of the supercontinent break-up, but he does not agree that meteorite impact can provide the driving force for continuous continental drift. Because, he explains, taking the northward drift of the Indian Plate as an example, the huge viscous resistance of the mantle requires numerous meteorites to hit the back of the Indian plate at fixed points before the Indian plate can continue to drift. Tang Chunan points to the Earths pot-cover effect: the upper mantle has a cold and hot period, and the crust will drift on a large scale during the hot period. According to the mechanical mechanism, the mid-ocean ridge and transform fault cannot be caused by seafloor spreading, but should be a fracture system caused by continental drift. Finally, Yang Weiran concludes that meteorite impact is an important factor; tectonic movements on the earth can be attributed to opening-closing movements; and seafloor spreading and continental drift exist, and terrane tectonics is scientific.
The consensus reached at the seminar is that there are indeed large-scale horizontal movements in the mainland continent, but the traditional mantle convection conveyor belt drive model has many problems in its inconsistency with the observation facts, therefore it is necessary to re-recognize the driving mechanism and the driving force. Most of the seminar participants express doubts or even opposition to the plate subduction argument. They consider the driving force should come from gravity and internal heat of the Earth, and more in-depth researches are required to understand their interactions.