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831.
832.
CO2-rich fluid inclusions containing opaque mineral crystals were found in the Fenghuangshan skarn-porphyry Cu–Fe–Au deposit
in Tongling, Anhui, China. These inclusions show variable CO2 contents and are accompanied by aqueous inclusions, both occurring as secondary inclusions in quartz and being locally associated
with chalcopyrite mineralization. Laser Raman microspectroscopic analyses confirm the predominance of CO2 in the vapor and the presence of H2S as high as 8 mol%, and identify the opaque mineral with yellow reflectance color in the inclusions as chalcopyrite. More
than half of the CO2-bearing inclusions contains chalcopyrite, whereas few of the associated aqueous inclusions do so. The chalcopyrite, occupying
less than 1% (volume) of the inclusions, is interpreted to be a daughter mineral, and calculated Cu concentrations in the
inclusions range from 0.1 to 3.4 wt%. Copper is inferred to have been transported in CO2-dominated fluids as HS− complexes. The occurrence of chalcopyrite daughter crystals in CO2-rich fluid inclusions indicates that CO2-rich vapor has the capacity of transporting large amounts of Cu, and possibly Au. This finding has significant implications
for metal transport and mineralization in hydrothermal systems enriched in CO2, such as orogenic-type and granitic intrusion-related gold deposits. 相似文献
833.
Hongfu Yin Qinglai Feng Aymon Baud Shucheng Xie Mike J. Benton Xulong Lai David J. Bottjer 《International Journal of Earth Sciences》2007,96(5):903-909
The mass extinction at the Permian–Triassic Boundary (PTB) is said to have been abrupt and probably caused by an extraterrestrial
impact. However, evidence from the Global Stratotype Section and Point (GSSP) of the base of the Induan at Meishan, China,
shows that the biotic crisis began prior to the level, in beds 25 and 26 at which the postulated impact event occurred. Evidence
of such an earlier biotic crisis occurs in other sections in South China, and in central and western Tethyan regions. This
event is characterized by the extinction of a range of faunas, including corals, deep-water radiolarians, most fusulinids
and pseudotirolitid ammonoids, and many Permian brachiopods. In all sections, this extinction level is usually a few decimeters
to meters below that of the main mass extinction in the event beds (25 and 26) at Meishan, and their correlatives elsewhere.
This earlier extinction event happened before the postulated bolide impact at the level of beds 25 and 26, and constrains
interpretation of the mechanisms that brought about this greatest mass extinction.
Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users. 相似文献
834.
835.
836.
甘肃沙区开发中果树资源的应用及良种区划 总被引:4,自引:2,他引:2
在论述甘肃沙漠戈壁地区的自然概况及沙区果树发展的现状之后,提出了甘肃沙区果树区划、适宜的优良果树树种、品种和果树在沙产业开发中的技术要点,并对沙区果树资源开发中需重点研究的问题提出了建议。 相似文献
837.
Partitioning of F between aqueous fluids and albite granite melt and its petrogenetic and metallogenetic significance 总被引:3,自引:0,他引:3
The fluid/melt partitioning experiments on fluorine were carried out in the system albite-H2O-HF atP = 100 MPa, 770°C ≤T≤800°C: and wt = 2% −6% conditions. The concentrations of fluorine in quenched glasses (melt) were determined
by electron microprobe and those of fluorine in the coexisting aqueous fluid were calculated by the method of mass balance.
The result shows that the fluorine was concentrated in granitic melt relative to the coexisting fluid. The partition coefficient
DF(wt
F
F1
/wt
F
Mt
) ranges from 0.35 to 0.89. It increases with increasing fluorine content in the system. This means that there is not just
one single value of partition coefficient for fluorine in the granitic melt-fluid system. The partitioning behavior of fluorine
in this system depends critically on fluorine and proton (H+) concentrations. Our data suggest that F-rich granitic melts exist in nature and that fluorine may not be an important complexing
agent of metal elements in F-bearing fluids.
The project was financially supported by both the National Natural Science Foundation of China (No. 49603048) and the State
Key Laboratory of Mineral Deposit Research, Nanjing University. 相似文献
838.
839.
Volcanism and Tectonic Evolution in the North Qilian Mountains during Ordovician Period 总被引:1,自引:0,他引:1
Lai Shaocong Department of Geology Northwest University Xi ’an Deng Jinfu Zhao Hailing Department of Geology China University of Geosciences Beijing 《中国地质大学学报(英文版)》1998,9(1)
INTRODUCTIONTheOrdovicianmarinevolcanicrocksinthenorthQilianhavebeenrepeatedlydiscussedforalongtimeandbeencon-sideredadistinc... 相似文献
840.
This paper studies the computation method of two-step inversion of interface and velocity in a region. The 3-D interface is
described by a segmented incomplete polynomial; while the reconstruction of 3-D velocity is accomplished by the principle
of least squares in functional space. The computation is carried out in two steps. The first step is to inverse the shape
of 3-D interface; while the second step is to do 3-D velocity inversion by distributing the remaining residual errors of travel
time in accordance with their weights. The data of seismic sounding in the Tangshan-Luanxian seismic region are processed,
from which the 3-D structural form in depth of the Tangshan seismic region and the 3-D velocity distribution in the crust
below the Tangshan-Luanxian seismic region are obtained. The result shows that the deep 3-D structure in the Tangshan seismic
region trends NE on the whole and the structure sandwiched between the NE-trending Fengtai-Yejituo fault and the NE-trending
Tangshan fault is an uplifted zone of the Moho. In the 3-D velocity structure of middle-lower crust below that region, there
is an obvious belt of low-velocity anomaly to exist along the NE-trending Tangshan fault, the position of which tallies with
that of the Tangshan seismicity belt. The larger block of low-velocity anomaly near Shaheyi corresponds to a denser earthquake
distribution. In that region, there is an NW-trending belt of high-velocity anomaly, probably a buried fault zone. The lower
crust below the epicentral region of the Tangshan M
S=7.8 earthquake is a place where the NE-trending belt of low-velocity anomaly meets the NW-trending belt of high-velocity
anomaly. The two sets of structures had played an important role in controlling the preparation and occurrence of the M
S=7.8 Tangshan earthquake.
Contribution RCEG97006, Research Center of Exploration Geophysics, China Seismological Bureau, China.
This project is supported by the Chinese Joint Seismological Science Foundation. 相似文献