Characteristics of melt inclusions in skarn minerals from Fe,Cu(Au) and Au(Cu) ore deposits in the region from Daye to Jiujiang

The skarns and skarn deposits are widely distributed at home and abroad. The skarn deposits include many kinds of ores and higher ore grade. Some of them are broad in scale. Scientists of ore deposits from different countries have paid and are paying grea…     

Late Mesozoic crust-mantle interaction and lower crust components in South China: A geochemical study of mafic granulite xenoliths from Cenozoic basalts

Mafic granulite xenoliths have been discovered in many volcanoes (especially alkali basalt and kimberlite) all over the world. They formed generally in lower crust, and recorded lots of in- formation on the lithosphere formation and crust-mantle interacti…     

Sea surface height and transport stream function of the South China Sea from a variable-grid global ocean circulation model

The study on the South China Sea (SCS) circulation has a history of more than 40 years. Nevertheless, the SCS circulation is not fully understood compared with the Bohai Sea, Yellow Sea and East China Sea (ECS). Many numerical studies on the SCS circulati…     

Geology and isotopic composition of helium,neon, xenon and metallogenic age of the Jinding and Baiyangping ore deposits,northwest Yunnan,China

TheJindingoredeposit,locatedinthenorthwestYunnanProvince,isthelargestPb-Zndeposit(Pb Zn>15Mt1),averagingZn=6.08%andPb/Zn=1/4.7)inChinaatpresent.Toitsnorth,alargeCu-Co-AgdeposithasbeenfoundatBaiyangpingrecently1).TheJindingPb-Zndepositishostedinsandstonesa…     

The carbon isotope composition of C<Superscript>3</Superscript> herbaceous plants in loess area of northern China

¹³C of 367 C₃ herbaceous plants was measured in loess area in northern China. Their δ¹³C values vary between −21.7%. and −30.0%., with a mean of −26.7%.. In the center of Loess Plateau (semimoist area) with annual precipitation of 400–600 mm, the δ¹³ C values of C₃ herbaceous plants range from −24.4%. to −28.5%., with a mean of −27.5%.. In the west of Loess Plateau (semiarid and arid area) with annual precipitation less than 400 mm, they range between −21.7%. and −30.0%., with a mean of −26.2%.. Annual precipitation is the main factor that makes δ¹³C values of C₃ herbaceous plants in the west greater than those in the central Loess Plateau. The composition of δ¹³C in C₃ plants increases with deceasing annual precipitation, and the mean change is −49%./100 mm.     

Sea-level changes and hydrothermal sedimentary mineralization of large-superlarge ore deposits among Sinian to Triassic in South China

Among the Sinian to Triassic strata in South China, the stratiform, quasi-stratiform and lenticular metallic deposits in association with hydrothermal sedimentation mainly occur in the four periods: (1) the Sinian Datangpo interglacial period, (2) the early period of Early Cambrian, (3) the late period of Middle Devonian to early period of Late Devonian, and (4) the late period of Early Permian. The four mineralization periods all happened around the maximum flooding period in the third-order seal-level cycle during the ascending stage in the first-order sea-level cycle. The deep seawater layer, starved and non-compensatory basin, low sedimentary rate, and low energy and anoxic environment during the maximum flooding period are very suitable for the formation and preservation of large to superlarge hydrothermal sedimentary deposits. The maximum flooding period also coincided with the intensified regional tectonism, extensive deep magmatism and hydrothermal sedimentation, which provide, for the formation of large to superlarge hydrothermal sedimentary deposits through the rapid accumulation of hydrothermal sediments, the needed dynamics, ore-forming materials and favorable passway for hydrothermal fluids to enter the basin.     

Geodynamic settings of Mesozoic large-scale mineralization in North China and adjacent areas

Based on the summary of the highly precise datings of the metal deposits and related granitic rocks in North China craton and adjacent areas, such as the molybdenite Re-Os datings,⁴⁰Ar-³⁹Ar datings of mica, K-feldspar and quartz, some Rb-Sr isochrons, and the SHRIMP zircon U-Pb dating and single grain zircon U-Pb dating, we suggest that the large-scale mineralization in North China craton and adjacent areas take place in three periods of 200-160Ma, 140Ma±, and 130-110Ma. Their corresponding geodynamic settings are proposed to be the collision orogenic process, transformation of the tectonic regime, and delamination of the lithosphere, respectively, in light of analyzing the Mesozoic geodynamic evolution in the North China craton.