In the semi‐arid region of the Loess Plateau in China, a portable photosynthesis system (Li‐6400) and a portable steady porometer (Li‐1600) were used to study the quantitative relation between the soil water content (SWC) and trees' physiological parameters including net photosynthesis rate (Pn), carboxylation efficiency (CE), transpiration rate (Tr), water use efficiency of leaf (WUEL), stomatic conductivity (Gs), stomatal resistance (Rs), intercellular CO2 (Ci), and stomatal limitation (Ls). These are criteria for grading and evaluating soil water productivity and availability in forests of Black Locust (Robinia pseudoacacia) and Oriental Arborvitae (Platycladus orientalis). The results indicated: To the photosynthesis of Locust and Arborvitae, the SWC of less than 4.5 and 4.0% (relative water content (RWC) 21.5 and 19.0%) belong to “non‐productivity and non‐efficiency water”; the SWC of 4.5–10.0% (RWC 21.5–47.5%) and 4.0–8.5% (RWC 19.0–40.5%) belong to “low productivity and low efficiency water”; the SWC of 10.0–13.5% (RWC 47.5–64.0%) and 8.5–11.0% (RWC 40.5–52.0%) belong to “middle productivity and high efficiency water”; the SWC of 13.5–17.0% (RWC 64.0–81.0%) and 11.0–16.0% (RWC 52.0–76.0%) belong to “high productivity and middle efficiency water”; the SWC of 17.0–19.0% (RWC 81.0–90.5%) and 16.0–19.0% (RWC 76.0–90.5%) belong to “middle productivity and low efficiency water”; the SWC of more than 19.0% (RWC 90.5%) belongs to “low productivity and low efficiency water”. The SWC of about 13.5 and 11.0% (RWC 64.0 and 52.0%) are called “high productivity and high efficiency water”, which provides the further evidence for Locust and Arborvitae to get both higher productivity (Pn and CE) and the highest WUEL and adaptation to the local environment, respectively. 相似文献
Fault geometry, kinematics, geophysics, the tectonic stress field and tectonic evolution of the Zhouwang fault in the southern Jiangnan tectonic transition zone of the Lower Yangtze region, eastern China are examined. Field observations show the fault is composed of a series of nearly E–W trending, N–S dipping faults, and four stages of tectonism (sinistral strike-slip, thrust nappe, normal fault, and dextral strike-slip) developed in turn. Geophysical data show that the fault trends almost linearly E–W along a flat, steep gravity gradient at shallow depth, with distinct gravity anomalies to the north and south and different in the north and south. Also, the deep part is characterized by northward dip and a gradual slowing down. Tectonic stress field analysis indicates that the fault experienced four tectonic movements: NNE–SSW compression, NNW–SSE compression, NEE–SWW extension, and E–W compression. Combined with regional tectonic background and previous research results, this indicates that: (1) the Zhouwang fault experienced sinistral strike-slip movement during the Indosinian Period (260–200 Ma); (2) thrust nappes developed during the early Yanshanian Period (163–145 Ma); (3) a normal fault occurred in the late Yanshanian Period (125–65 Ma); and (4) dextral strike-slip movement occurred in the Himalayan Period (ca. 50–37 Ma). The results reveal the tectonic evolution of the fault during Mesozoic deformation in the area, and also reveal the geological evolution and tectonic transformation of the Lower Yangtze region, which is key to our understanding of intracontinental deformation in eastern China. 相似文献
The Sin Quyen Cu–Fe–Au–REE deposit is localized in the Proterozoic deposits of the Phan Xi Pang zone, northern Vietnam. The mineralization is formed by lenticular and sheet-like bodies occurring concordantly with the host rocks. Seventeen orebodies have been recognized in the deposit, which form an ore horizon up to 140 m in total thickness, about 2 km in strike, and up to 350 m in dip. The ores are of simple mineral composition: Au-rich copper and iron sulfides (chalcopyrite, pyrite, pyrrhotite) and iron oxides (magnetite, hematite). Gold and silver are distributed unevenly in the ores: Their contents vary from hundredths and tenths of ppm to 1.8 ppm. Copper sulfide ores are the main concentrator of gold and silver. All ores are characterized by high REE contents, tens and hundreds of times exceeding the element clarkes. The highest contents have been revealed for Ce and La. Orthite is the main carrier of REE. No correlation between REE and ore elements of sulfide-oxide ores has been revealed, which points to the independent formation of the mineralization. Orebodies together with the host rocks underwent metamorphism at 500–600 to 630–685 °C and 3–7 kbar. The spatial association of the mineralization with amphibolites (metamorphosed basites) and the mineral composition of ores suggest that the Sin Quyen deposit is of Cyprian volcanogenic type. 相似文献