Cheng Y.-M.,The Geological Museum of China
Review of Palaeobotany and Palynology | Year: 2011
A new species, Ashicaulis claytoniites, is established based on two specimens collected from Middle Jurassic sediments near Duanmugou, Changgao Village, Beipiao County, west Liaoning Province of China. The specimens represent stems surrounded by a mantle of stipular petiole bases and adventitious roots. The stems, 6-8. mm in diameter, consist of an ectophloic dictyoxylic stele and a two-layered cortex containing 31-37 leaf traces. When departing from the stele, the leaf traces are a flattened C-shaped, with an endarch protoxylem which bifurcates at the base of petiole. The sclerenchyma ring is heterogeneous with an arch of stipular petiole base at the base that are divided into two lateral strands at the top. A big mass heterogeneous sclerenchyma is present in the stipular wing. In the ectophloic dictyoxylic stele and arrangement of sclerenchyma of the petiole base, Ashicaulis claytoniites shares smiliarities with Osmunda claytoniana L. of Osmunda subg. Osmunda, but not with other subgenera of Osmunda subg. Plenasium, Osmundastrum, the genera Todea, and Leptopteris in the extant Osmundaceae. According to the similarities of these features, a distinct relationship is suggested between Ashicaulis claytoniites and Osmunda claytoniana. The new species could be a close Mesozoic relative of O. claytoniana. This new species shows the similar arrangement of the sclerenchyma of the petiole base with the Mesozoic species, Millerocaulis preosmunda, suggesting that the morphogenera Millerocaulis and Ashicaulis are closely related, and the new species may be a transitional form between the Mesozoic M. preosmunda and Osmunda claytoniana of extant subgenus Osmunda. © 2011 Elsevier B.V.
Huang J.-N.,The Geological Museum of China |
Zhao P.-D.,China University of Geosciences
Diqiu Kexue - Zhongguo Dizhi Daxue Xuebao/Earth Science - Journal of China University of Geosciences | Year: 2011
The east Tianshan ore-belt is one of the most important ore concentrated districts of Cu-Au in China. Long and complicated geological evolution created a complex geological background, multi-periods and diversity of mineralization. In this study, stream sediment survey data of Cu-Au are used for spatial distribution analysis, and then Geostatistical method and Spectrum-Area (S-A) method are implemented to obtain ore-forming information at different scale. The research results are as follows: (1) the modeling semivirograms show the max range of Cu and Au are 80 km and 47 km, the direction of max range is along the trend of regional deep faults, which are the major factors controlling the distribution of Cu, Au concentration. Cu concentration exhibits more strong structure character than Au in region. (2) Both low pass filtering in S-A and universal Kringing can obtain the similar ore forming information which reflect the regularity of enrichment of ore-forming elements caused by regional mineralization. (3) Multi-fractal filtering can effectively decompose the concentration data from stream sediment survey in complicated geological setting into different hierarchy, including local anomalies and regional anomalies. Different anomaly filters defined in ln(Spectrum)-ln(Area) plot can be constructed to obtain Cu and Au anomalies at different scale. The local Cu anomalies obtained by S-A method are spatially associated with known Cu deposits, which reveal some conceal ore-forming information in low background. The local anomalies of Au in pinch-and-swell and oriented in North-East trend obtained by S-A method may imply that the gold mineralization is controlled by sub-fault system in NE trend.
Wang H.,Nanjing University |
Wang H.,State Oceanic Administration |
Xu Z.,Nanjing University |
Lu X.,Nanjing University |
And 4 more authors.
Lithos | Year: 2016
The origin and tectonic setting of Early Cretaceous adakitic rocks from the Luxi terrane in the eastern North China Block (NCB) remain debated. To resolve this issue, we determined whole-rock geochemistry, zircon U-Pb ages, and in situ Hf-O isotopes of the Mengyin and Liujing adakitic porphyries from the Luxi terrane. Zircon U-Pb dating results reveal that both the Mengyin and Liujing plutons were emplaced during the Early Cretaceous, with weighted mean 206Pb/238U ages of 130±1Ma (2σ) and 131±2Ma (2σ), respectively. In addition, abundant Neoarchean-Paleoproterozoic inherited zircon cores are identified in the Mengyin adakitic porphyry with 207Pb/206Pb ages ranging from 2.53 to 2.42Ga. Rocks of both plutons are silicic (SiO2=65.4-70.2wt.%), metaluminous, and alkaline in composition, comprising mainly quartz syenite porphyries. Samples from both plutons are enriched in large ion lithophile elements (LILEs) (e.g., Rb, Sr, and Ba), and light rare earth elements (LREEs), depleted in high field strength elements (HFSEs) (e.g., Nb, Ta, and Ti), and heavy rare earth elements (HREEs), and have either positive or no Eu anomalies. In addition, both adakitic porphyries have high Mg# values (51-64), high Sr and La contents, low Y and Yb contents, and high Sr/Y (Mengyin=149-264; Liujing=58-110) and (La/Yb)N (Mengyin=32.4-45.3; Liujing=43.8-53.1) ratios, similar to adakitic rocks worldwide. The Mengyin adakitic porphyry has higher whole-rock εNd(t) values (-5.8 to -4.1), more radiogenic Pb [(206Pb/204Pb)i=18.35-18.39, (207Pb/204Pb)i=15.55-15.56, (208Pb/204Pb)i=38.20-38.23], higher zircon rim εHf(t) values (+3.3 to +8.8) and δ18O values (+6.5‰ to +7.9‰), and lower (87Sr/86Sr)i ratios (0.7049-0.7050) than the Liujing adakitic porphyry [εNd(t)=-12.4 to -12.2, (206Pb/204Pb)i=17.63-17.72, (207Pb/204Pb)i=15.56-15.58, (208Pb/204Pb)i=37.76-37.94, εHf(t)=-14.8 to -11.2, δ18O=+5.9‰ to +7.1‰, (87Sr/86Sr)i=0.7090-0.7091]. The Mengyin adakitic porphyry was most likely derived from partial melting of subducted oceanic slab with some input of NCB Neoarchean-Paleoproterozoic lower crust components. The Liujing adakitic porphyry was probably derived from partial melting of delaminated newly underplated thick lower crust, which then interacted with above asthenospheric mantle peridotite. Slab rollback together with the ridge subduction of the Paleo-Pacific slab was the most likely geodynamic mechanism for formation of the Early Cretaceous Mengyin and Liujing adakitic porphyries. © 2015 Elsevier B.V..
Cao Y.,China University of Geosciences |
Li S.,China University of Geosciences |
Yao M.,China University of Geosciences |
Niu H.,China University of Petroleum - Beijing |
And 5 more authors.
Carpathian Journal of Earth and Environmental Sciences | Year: 2012
Otolith is a typical biomineral carrier growing on insides of fish skull with prominent zoning structure formed by alternating layers of protein and calcium carbonate growing around the nucleus. Even though thermoluminescence (TL) analysis on biomineral has been widely used to measure the radiation exposure in recent twenty years, the TL characteristics of the fish otolith have not yet been reported in the literature. TL characteristics of otoliths from the wild carps (cyprinoid) living in the Baiyangdian Lake, Hebei Province and Miyun Reservoir, Beijing City was firstly studied, as well as the differences of energy gap (E) between the fish otoliths in the two waters have also been discussed in this paper. The experimental results indicate that TL curve parameters: peak temperature (Tp), luminous intensity (I), integrated intensity (S) and middle width (Wm) for the glow curves of the cyprinoid otoliths from Baiyangdian Lake are greater than those from Miyun reservoir, and the stability of the formers' TL curve parameters value and energy gap (E) is weaker than the latters'. In comparison to the Miyun Reservoir, the analysis manifest that the electrons and vacancies that trapped in the otoliths from Baiyangdian Lake are more likely to escape. According to the investigation, the contaminative degree and eutrophication in the water of Baiyangdian Lake is heavier than that of Miyun Reservoir. So the characteristics of TL growth curves of the cyprinoid otoliths is quite sensitive to heavier contaminated and less contaminated water, and it could be regarded as an important typomorphic biomineral for monitoring the contaminative degree and environment change of the water.
Cheng Y.-M.,The Geological Museum of China |
Yang X.-N.,The Geological Museum of China
Journal of Asian Earth Sciences | Year: 2016
The Qaidam Basin with the most complete Cenozoic sedimentary preservation in northern Qinghai-Tibet Plateau is a key area for studying uplift and environmental change of the plateau. Three types of woods, Ulmus (Ulmaceae), Leguminosae (?) (angiosperm) and Cupressaceae (gymnosperm) were recognized from the large-scale preservation of fossil woods in late Miocene Shang Youshashan Formation in northern Qaidam Basin on the Qinghai-Tibet Plateau. Both investigations of their Nearest Living Relatives (NLRs) and previous grassland mammal evidences suggest that there have been temperate deciduous broad-leaved forest and needle-leaved forest with grass in northern Qaidam Basin during the late Miocene in contrast to the desert vegetation found there nowadays. The presence of the ancient forest steppe further implies that the southern part of the plateau used to be adequately low, so that the Indian and East Asian monsoons could approach the northern area and to accommodate the vegetation in late Miocene. © 2015 Elsevier Ltd.