关键词: 沉降史, 构造演化, 天然气水合物, 三露天井田

Abstract:

According to drillhole and geological survey report of Sanlutian mining field in Juhugeng mining area, we inversed and analyzed the subsidence history of Sanlutian mining field by back-stripping method and discussed the relationship between hydrate formation and tectonic evolution. The simulated results showed that the study area experienced four stages of subsidence and three stages of uplift since Carboniferous period as follows: subsiding slowly then rapidly with larger subsidence scope from Carboniferous to Late Triassic, uplifting and denudating in the end of Late Triassic by the late Indosinian movement, subsiding rapidly from Early Jurassic to Early Cretaceous, uplifting and denudating in Late Cretaceous by Yanshan movements,subsiding rapidly in Miocene epoch, uplifting rapidly with the uplift of the Tibetan Plateau in Pliocene epoch, and subsiding rapidly in Quaternary period. The simulation result of subsidence history provides a quantitative or semi-quantitative value of parameters for the tectonic evolution in the study area.The control of the tectonic subsidence on the formation of natural gas hydrate shows the two aspects, the maturity of source rocks and the formation of hydrate stable zone.

Key words: subsidence history, tectonic evolution, natural gas hydrate, Sanlutian mining field