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In order to study the effects of the complexity of raw materials such as collagen and edible fungi on the quality of yak meat enema products and the quality changes in the storage process, and to determine the best processing process of yak meat enema. The study took yak meat enema as the test object, with adding amounts such as yak hoof tendons, shiitake mushrooms, salt and rice wine as the influencing factors. A four-factor, three-level response surface analysis test was conducted using the Box-Behnken method with the sensory evaluation as the response values and a quadratic multinomial regression model was developed based on a single-factor experiments. On this basis, the storage test of yak sausage was carried out, and the changes of edible quality and rheological properties of it were measured and analyzed after 0, 2, 4, 6, 8 and 10 days of storage at 4 ℃. The results showed that the optimal formula of collagen-edible fungi sausage was 10% shiitake mushrooms, 2% yellow rice wine, 20% yak tendon, and 2% salt. Meanwhile, the score of yak sausage was the highest and the quality was the best. The storage test showed that with the extension of the time, the water holding capacity (WHC), pH value, L* value, a* value, hardness, chewiness and recovery of yak sausage gradually decreased, while the b* value and cooking loss gradually increased. Cohesiveness and elasticity did not change significantly, but rheological properties changed significantly (P

Abnormally low pressure is characteristic of the Mesozoic reservoirs in the Ordos Basin. Based on the study of low pressure distribution, the formation mechanisms of abnormally low pressure were quantitatively analyzed from several aspects, such as tectonic uplift, stratum temperature decrease and dissolution-increased porosity. The Mesozoic reservoir pressure experienced two major evolutionary stages: the pressure rising to maximum pressure stage from the Late Triassic to the Early Cretaceous, the pressure decreasing to abnormally low pressure stage from the end of Early Cretaceous to now. Since the late Early Cretaceous, porosity rebound caused by tectonic uplift, stratum temperature decrease and dissolution caused pressure decrease of up to 20–25 MPa, the decrease ratio is about 54%-77%. The three factors are the main reason for the pressure decrease of the Mesozoic in the Ordos Basin, and among them stratum temperature decrease is the most important factor. Combined with other factors, they made the formation pressure reduced gradually and eventually formed the abnormally low pressure distribution pattern of 10–18 MPa. Key words: abnormally low pressure, tectonic uplift, stratum temperature decrease, dissolution, Yanchang Formation, Mesozoic, Ordos Basin