Design and Construction of Lightweight Domain Ontology of Tectonic Geomorphology

As data size grows and computing power evolves, artificial intelligence has become one of the most important tools for assisting data-intensive scientific discoveries. The development of artificial intelligence applications in geoscience requires the understanding of enormous quantities of concepts and thus requires the organization of knowledge into a structured form, which is ontology. Compared with common-sense ontologies, the concepts in geoscience are extremely abstract and difficult to understand. It is challenging to use natural language processing technologies to build ontologies in geoscience from the bottom up. Meanwhile, applications of ontology in deep learning and data integration also reveal the importance of constructing a geoscience ontology. Because of the complexity and transdisciplinary nature, this study focuses on the field of tectonic geomorphology. Based on the understanding and experience of experts in geoscience, a top-down approach is used to construct a tectonic geomorphology ontology as part of the geoscience ontology. This research started with the proposal of a method for constructing ontologies, then built a tectonic geomorphology ontology, and finally checked, validated, and applied the ontology, covering common concepts in geoscience and dedicated concepts in tectonic geomorphology. The tectonic geomorphology ontology is an important part of the whole geoscience ontology.

Channel flow of the lower crust and its relation to large-scale tectonic geomorphology of the eastern Tibetan Plateau

The Tibetan Plateau is a large-scale tectonic geomorphologic unit formed by the interactions of plates.It has been commonly believed that convective removal of the thickened Tibetan lithosphere,or lateral flow of the lower crust beneath the Tibetan plateau plays a crucial role in the formation of the large-scale tectonic geomorphologic features.Recent geological and geo-physical observations have provided important evidence in support of the lower crustal channel flow model.However,it re-mains unclear as how the geometry of lower crustal channel and the lateral variation of crustal rheology within the lower crust channel may have affected spatio-temporal evolution of the tectonic geomorphologic unit of the Tibetan Plateau.Here,we use numerical methods to explore the mechanical relations between the lower crustal channel flow and the tectonic geomorpho-logic formation around the eastern Tibetan plateau,by deriving a series of governing equations from fluid mechanics theory.From numerous tests,our results show that the viscosity of the channeled lower crust is about(1-5)×1018 to(1-4)×1020 Pa s(Pa.s) beneath the margin of the eastern Tibetan Plateau,and increases to about 1022 Pa s beneath the Sichuan Basin and the southern region of Yunnan Province.Numerical tests also indicate that if channel flows of the lower crust exist,the horizontal propagation and the vertical uplifting rate of the eastern Tibetan Plateau margin could be accelerated with the time.Thus,the present results could be useful to constrain the rheological structure of the crust beneath the eastern Tibetan plateau,and to understand the possible mechanics of rapid uplift of the eastern Tibetan Plateau margin,especially since its occurrence at 8Ma as revealed by numerous geological observations.

Large-Scale Dextral Strike-Slip Movement and Associated Tectonic Deformation Along the Red-River Fault Zone

Field investigation has revealed that the large-scale dextral strike-slip movement and the associated tectonic deformation along the Red River fault zone have the following features: geometrically, the Red River fault zone can be divided into three deformation regions, namely, the north, central and south regions. The north region lies on the eastern side of the Northwest Yunnan extensional taphrogenic belt, which is characterized by the 3 sets of rift-depression basins striking NNW, NNE and near N-S since the Pliocene time, and on its western side is the Lanping-Yunlong compressive deformation belt of the Paleogene to Neogene; the deformation in the central region is characterized by dextral strike-slip or shearing. The east Yunnan Miocene compressive deformation belt lies on the eastern side of the fault in the south, and the Tengtiaohe tensile fault depression belt is located on its west. In terms of tectonic geomorphology, the aforementioned deformation is represented by basin-range tectonics in the north, linear faulted valley-basins in the central part and compressive (or tensional) basins in the south. Among them, the great variance in elevation of the planation surfaces on both sides of the Cangshan-Erhai fault suggests prominent normal faulting along the Red River fault since the Pliocene. From the viewpoint of spatial-temporal evolution, the main active portion of the fault was the southern segment in the Paleogene-Miocene-Pliocene, which is represented by “tearing” from south to north. The main active portion of the fault has migrated to the northern segment since the Pliocene, especially in the late Quaternary, which is characterized by extensional slip from north to southeast. The size of the deformation region and the magnitude of deformation show that the eastern plate of the Red River fault has been an active plate of the relative movement of blocks.

Late Quaternary Geomorphology of the Tonami Plain and Activity of the Tonami-Heiya Fault Zone, Toyama Prefecture, Central Japan

The Holocene alluvial fans and flood plains formed by the Sho and Oyabe Rivers spread out in the Tonami plain from the central through the northern parts in the Toyama Prefecture, central Japan. Along the foot of the surrounding mountains and hills, higher, middle and lower terraces of late Pleistocene-Holocene in age are distributed. These terraces have been displaced, by the reverse dip-slip activities of Tonami-heiya fault zone in a sense of upheaval in the mountains side, even during the Holocene time. We examined stratigraphic cross section utilizing borehole data and geomorphologically analyzed 5 m-DEM data in order to elucidate the fault trace of the Isurugi fault which Tonami-heiya fault zone. As the results, the northern segment of Isurugi fault seems to run along the northeastern foot of Hodatsu Hills and extends underground through the lower-most Oyabe River into the Toyama Bay. Consequently, its total length reaches about 30 km. In the southern segment, a continuous fault scarplet was recognized to cut across the lower dissected fans. The slip-rate of Isurugi fault is estimated to be 0.31 - 0.64 m/kyr. In the Hokuriku region, reverse faulting and related folding with strike in a NE-SW direction have occurred during the late Quaternary. The hinge line of block movement due to the activities of the Tonami-heiya fault zone is revealed to have shifted from the mountain side into the plain side within the Holocene time. In conclusion, the Quaternary folding and faulting associated with the crustal warping at a wavelength of about 20 km is currently in progress, causing both the subsidence of Tonami plain and the upheaval of surrounding mountains and hills.

Structure,Timing,and Mechanism of the Pliocene and Late Miocene Uplift Process of the Ailao Shan-Diancang Shan,SE Tibet,China

The uplift of the Ailao Shan-Diancang Shan （ASDS） along the Ailao Shan-Red River （ASRR） shear zone is an important geological event in the southeastern margin of Qinghai-Tibet Plateau tectonic domain in the Late Cenozoic, and it preserves important information on the structures, exhumationai history and tectonic evolution of the ASRR shear zone. The uplift structural mode and uplift timing of the ASDS is currently an important scientific topic for understanding the ASDS formation and late stage movements and evolution of the ASRR shear zone. The formation of the ASDS has been widely considered to be the consequence of the strike-slip movements of the ASRR shear zone. However, the shaping of geomorphic units is generally direct results of the latest tectonic activities. In this study, we investigated the timing and uplift structural mechanism of the ASDS and provided the following lines of supportive evidence. Firstly, the primary tectonic foliation of the ASDS shows significant characteristic variations, with steeply dipping tectonic foliation developed on the east side of the ASDS and the relatively horizontal foliation on the west side. Secondly, from northeast to southwest direction, the deformation and metamorphism gradually weakened and this zone can be further divided into three different metamorphic degree belts. Thirdly, the contact relationship between the ASDS and the Chuxiong basin-Erhai lake is a normal fault contact which can be found on the east side of the ASDS. 40^Ar/^39 Argeochronology suggests that the Diancang Shan had experienced a fast cooling event during 3-4 Ma. The apatite fission track testing method gives the age of 6.6-10.7 Ma in the Diancang Shan and 4.6-8.4 Ma in the Ailao Shan, respectively. Therefore the uplift of the ASDS can be explained by tilted block mode in which the east side was uplifted much higher than the west side, and it is not main reason of the shearing movements of the ASRR shear zone. The most recent uplift stages of the ASDS happened in the Pliocene （3-4 Ma） and Late Miocene （6-10 Ma）.