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Zhang H.,Changan University | Liu J.,Changan University | Peng S.,Xian Center | Zhang S.,Changan University | Wang D.,Changan University
Jilin Daxue Xuebao (Diqiu Kexue Ban)/Journal of Jilin University (Earth Science Edition) | Year: 2014

Plagioclases with special zonal structure were seen occasionally in diorite intrusion in Pingshun, southern Taihang Mountains. The plagioclases is characterized by high Ca-riched basic plagioclases (An>63) in the core and Na-riched in the rim, and a corrosion zone formed between the core and the rim that composed epidote and sericite. In addition there are distinctive compositional differences between core and rim of the plagioclase xenocrysts. Based on the evidences from the components and textures of the plagioclause, the following scenario about the magma evolution is tentatively suggested. Mantle magma originating from the EMI underplated to lower crust and crystallized Ca-riched basic plagioclases under high temperature. Crustal source magma originated by melting of lower crust with the help of heat-carrying mantle magma. Mantle magma and crustal magma ascended quickly along Taihang deep fault, intruded into shallow crust, and mixed. Meanwhile, early-formed basic plagioclases dissoluted because of sudden reduced pressure and formed corrosion zone with irregular shape. The crust-mantle magma crystallized Na-riched plagioclases on the basis of Ca-riched basic plagioclases and formed plagioclases with special zonal structure, providing the most direct evidence to magma mixing in the study area. Source

Zhou W.,CAS Institute of Earth Environment | Zhou W.,Xian Center | Zhou W.,Xian Jiaotong University | Zheng Y.,CAS Institute of Earth Environment | And 4 more authors.
Earth and Planetary Science Letters | Year: 2010

The peat sequence at Hani in northeastern China accumulated over the past 16. cal. kyr in a percolation mire in which rain water and ground water seeped through the peat system. The molecular compositions of n-alkanes, n-alkanols, and n-alkanoic acids extracted from the Hani peat sequence reveal different responses to the progressive evolution of climate and changes in the nature of the peat-forming vegetation. Long chain length components that originate from the waxy coatings of subaerial vascular plants dominate the n-alkane distributions throughout the Hani peat sequence. The paleoclimate integrity of these biomarker molecules appears to be well preserved. Most of the n-alkanol distributions are similarly dominated by long chain components that indicate their origins from subaerial plants. In contrast, n-alkanoic acid distributions are dominated by secondary components that record the importance of post-depositional microbial activity in this peat sequence, which evidently can be extensive in a percolation mire.Elevated n-alkane Paq values and C23/C29 ratios, which are both molecular proxies for water-loving plants, record an especially moist local climate in the Bølling-Allerød (14.5 to 12.9ka), Younger Dryas (12.9 to 11.5ka), and Pre-Boreal (11.5 to 10.5ka) portions of the Hani peat sequence. Depressed Paq values and C23/C29 ratios and larger n-alkane average chain length values indicate that the Holocene Climatic Optimum (10.5 to 6ka) was a period of warmer climate with lower effective precipitation, which contrasts with evidence of wetter climates in most of East Asia. © 2010 Elsevier B.V. Source

Zheng Y.,Northwest University, China | Zheng Y.,CAS Institute of Earth Environment | Zhou W.,CAS Institute of Earth Environment | Zhou W.,Xian Center | And 2 more authors.
Organic Geochemistry | Year: 2011

Most research on long chain methyl ketones has focused on their origins and distributions. Their application in paleoclimate studies is less common than that of other n-alkyl lipids. The goal of this research was to explore this potential by studying n-alkan-2-ones from the Hani peat sequence in northeastern China. They were identified using gas chromatography-mass spectrometry (GC-MS) and showed a distribution ranging from C19 to C31 with a strong odd/even predominance. This type of distribution is considered to derive from Sphagum and microbial oxidation of n-alkanes. Comparison with climate sensitive indicators and macrofossil analysis shows that microbial oxidation of n-alkanes derived from higher plants was enhanced during the warm early Holocene period. This led us to develop three n-alkan-2-one proxies - C27/ΣC23-31 (C27/HMW-KET), carbon preference index (CPIH-KET) and average chain length (ACL(27-31)-KET) - as possible indicators of paleoclimate in the peat-forming environment. These proxies, in combination with C27 n-alkane δD values and peat cellulose δ18O records, might allow examination of paleo-ecosystem behavior during climatic evolution in northeastern China over the past 16,000yr. © 2010 Elsevier Ltd. Source

Cheng D.-H.,Changan University | Wang W.-K.,Changan University | Hou G.-C.,Xian Center | Yang H.-B.,Changan University | And 2 more authors.
Jilin Daxue Xuebao (Diqiu Kexue Ban)/Journal of Jilin University (Earth Science Edition) | Year: 2012

The relationship between vegetation and groundwater in the hinterland of Mu Us Desert with 6 indicators, such as vegetation populations and cover, groundwater depth and mineralization, vadose zone moisture content and salinity, were investigated. We established the suitable depth of groundwater, unsaturated zone moisture content, groundwater salinity and the vadose zone salinity for dominated vegetation, Artemisia, Salix psammophila and Carex. The results showed that vegetation populations is very sensitive to groundwater depth and vadose zone moisture content, while vadose zone salinity and groundwater mineralization are non-sensitive indicators. In addition, the vegetation, the moisture of which for growth obtained from groundwater, its cover is more sensitive to groundwater depth, while the total coverage is non-sensitive indicators. Source

Qiao G.,Xian Center | Wang P.,Petrochina | Wu Y.,Xian Center | Du W.,Changan University | And 3 more authors.
Jilin Daxue Xuebao (Diqiu Kexue Ban)/Journal of Jilin University (Earth Science Edition) | Year: 2015

Karakorum metallogenic belt is one of the hot area for the mineral resource exploration and development in West China with a great prospecting potential. According to the metallogenic theories established by the geologists of China, Karakorum metallogenic belt are further researched based on the metallogenic characteristics and its feature of geological formation. In the light of the time-space relationship of the mineralization and the geological formation, the related metallogenic series can be divided into syngenetic, epigenetic, and superficial weathering metallogenic series. These metallogenic series existed in the same geological formation naturally constitute a metallogenic serie family. In this study, 9 metallogenic serie families and 12 metallogenic series are summed up for the main mineral deposits of Karakorum metallogenic belt. On the basis of the mineralization pedigree, from their tectonic evolution angle, we further discussed its dynamic background of the formation for the metallogenic serie families, which provides the basis for clarifying the regional metallogenic regularity. ©, 2015, Jilin University Press. All right reserved. Source

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