The low‐Sr content (generally < 100 μg g−1) in clinopyroxene from peridotite makes accurate Sr isotopic determination by LA‐MC‐ICP‐MS a challenge. The effects of adding N2 to the sample gas and using a guard electrode (GE) on instrumental sensitivity for Sr isotopic determination by LA‐MC‐ICP‐MS were investigated. Results revealed no significant sensitivity enhancement of Sr by adding N2 to the ICP. Although using a GE led to a two‐fold sensitivity enhancement, it significantly increased the yield of polyatomic ion interferences of Ca‐related ions and TiAr+ on Sr isotopes. Applying the method established in this work, 87Sr/86Sr ratios (Rb/Sr < 0.14) of natural clinopyroxene from mantle and silicate glasses were accurately measured with similar measurement repeatability (0.0009–0.00006, 2SE) to previous studies but using a smaller spot size of 120 μm and low‐to‐moderate Sr content (30–518 μg g−1). The measurement reproducibility was 0.0004 (2s, n = 33) for a sample with 100 μg g−1 Sr. Destruction of the crystal structure by sample fusion showed no effect on Sr isotopic determination. Synthesised glasses with major element compositions similar to natural clinopyroxene have the potential to be adopted as reference materials for Sr isotopic determination by LA‐MC‐ICP‐MS.

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Extensive water–rock interaction in the Three Gorges Reservoir area of the Yangtze River leads to rock mass deterioration along the reservoir banks. However, mineral evolution behavior and its effect on the mesostructure deterioration of rocks under the wetting–drying cycle condition remain unknown. So, the wetting–drying cycle tests were conducted on peculiar argillaceous quartz sandstone in TGRA under neutral (pH = 7) and alkaline (pH = 10) water environments. Here, we provided detailed physical and microscopy images data to determine the control mechanism of mineral behavior on the evolution of sandstone’s mesostructure. Under the neutral condition, repeated “absorption and swelling–dehydration and contraction” of clay minerals leads to the repeated physical action of “squeezing–unloading” in the interior of a rock. This results in the initiation and gradual expansion of cracks in the framework mineral quartz, exhibiting failure mode from the interior to the exterior. In contrast, under the alkaline condition, the dissolution on the surface of quartz particles leads to the expansion and connection of pores, implying that the sandstone exhibits failure mode from the exterior to the interior. Moreover, the internal mechanical analysis indicates the minerals are at high pressure because of the expansion of clay minerals in the neutral solution. However, in an alkaline water environment, the extrusion pressure of framework mineral quartz decreases significantly and is not easily broken due to increased porosity. Thus, the evolution behavior of minerals in different water environments plays an important role in the damage of the rock.

Lherzolite xenoliths entrained in the Changle Cenozoic basalts were analyzed to infer mantle process beneath the eastern block of the North China Craton. These xenoliths were classified into two types. Clinopyroxenes (Cpx) in the type-1 xenoliths are strongly enriched in large ion lithophile elements and light rare earth elements (LREE) but depleted in high field-strength elements and heavy rare earth elements, and show high Ca/Al, Zr/Hf, and (La/Yb) N ratios but low Ti/Eu ratios. These features indicate that they were crystallized from a carbonatitic melt. Cpx in the type-2 xenoliths are mostly characterized by a chemical zonation, that is, LREE and Sr contents and (La/Yb) N and Eu/Ti ratios gradually increase from the cores to the rims. Some fresh cores preserve the original signatures of the depleted mantle. These observations indicate partial modification of pre-existing Cpx by carbonatite metasomatism. Two episodes of metasomatism were identified based on Sr isotopic compositions of Cpx and carbonate inclusions within olivines. Both the carbonate inclusions and Cpx cores in the type-2 xenoliths have relatively high 87 Sr/ 86 Sr ratios (>0.7033), suggesting metasomatism due to CO 2 -rich silicate melt derived from the recycled oceanic crust. However, low 87 Sr/ 86 Sr ratios of Cpx rims in the type-2 xenoliths suggest a late stage of metasomatism by a low-87 Sr/ 86 Sr carbonatitic melt (<0.7024), which might have been caused by upwelling of the asthenosphere mantle. Such multiple metasomatism could have played an important role in changing the chemical composition of mantle from refractory and depleted to fertile and enriched.

This study aimed to elucidate the damage mechanism of prestressed sandstone under uniaxial compression through the distribution characteristics of meso-structures. Four prestress levels, i.e., 0MPa, 15MPa, 30MPa, and 40MPa were selected. Nuclear Magnetic Resonance and Scanning Electron Microscope techniques were employed to observe the distribution characteristics of meso-structure within rocks and to further its damage mechanism. The results show that, compare with untreated specimens (0MPa), damaged specimens by 15MPa show a more porous meso-structure due to pores/cracks propagation which occurs between skeleton minerals and filler materials. Furthermore, specimens treated by 30MPa and 40MPa show low failure strength because micro-pores/cracks initiation inside skeleton minerals causes high deterioration. By meso-mechanics analysis, particle rotation leads to pores/cracks propagation and slightly modifies the meso-structure under low-prestress conditions. With the increase of the prestress, the transgranular cracks initiation and propagation will transform the skeleton structure of rocks, leading to significant rock deterioration.