Significance: The ancient topography of the Tibetan Plateau and its role in biotic evolution are still poorly understood, mostly due to a lack of fossil evidence. Our discovery of ∼47-Mya plant fossils from a present elevation of 4,850 m in central Tibet, diminishes, significantly, that lack of knowledge. The fossils represent a humid subtropical vegetation and some of the 70 different plant forms show affinity to Early-Middle Eocene floras in both North America and Europe. Using leaf architecture, we calculate that the forest grew at ∼1,500-m elevation within an east–west trending valley under a monsoonal climate. Our findings highlight the complexity of Tibet’s ancient landscape and emphasize the importance of Tibet in the history of global biodiversity.
Given that most species that have ever existed on earth are extinct, it stands to reason that the evolutionary history can be better understood with fossil taxa. Bauhinia is a typical genus of pantropical intercontinental disjunction among the Asian, African, and American continents. Geographic distribution patterns are better recognized when fossil records and molecular sequences are combined in the analyses. Here, we describe a new macrofossil species of Bauhinia from the Upper Miocene Xiaolongtan Formation in Wenshan County, Southeast Yunnan, China, and elucidate the biogeographic significance through the analyses of molecules and fossils.
Southern Hunan Province, located in the Cathaysia Block where the Shi–Hang zone and Nanling belt meet, is characterized by extensive Mesozoic magmatism and coeval polymetallic mineralization. The Huangshaping W–Mo–Pb–Zn–(Cu) deposit is representative in this area. However, the petrogenesis of the granitoids associated with the Huangshaping deposit, and their relationships with mineralization, remain undetermined. In this paper we focus on zircon U–Pb dating, whole-rock geochemistry, and Sr–Nd–Pb–Hf isotopic compositions in order to further our understanding of these issues, as well as their regional implications. The Huangshaping granitoids are characterized by two pulses of intrusive activity: a first-stage quartz porphyry and a second-stage felsite and granite porphyry, our new data show that the quartz porphyry and felsite formed at 160.5 ± 1.3 and 156.6 ± 1.4 Ma, respectively, representing a period of Late Jurassic magmatism. Granitic enclaves within the quartz porphyry crystallized at 160.2 ± 1.6 Ma, and zircons and apatites from the enclaves exhibit Hf isotopic and geochemical compositions that suggest a Palaeoproterozoic lower crustal melt as one end-member of the magma that formed the quartz porphyry, whereas another likely end-member was coeval mantle-derived magma, as indicated by the geochemistry and Sr–Nd–Pb–Hf isotopes. However, both the felsite and granite porphyry were probably derived from the melting of metamorphic basement rocks in the upper crust. The felsite clearly formed as a result of the rapid ascent and cooling of magma, whereas the granite porphyry underwent fractional crystallization. The magma sources and evolution of the granitoids, as well as their association with the Huangshaping mineralization, suggest that melting of upper crustal components controlled the W–Mo and Pb–Zn mineralization, whereas dehydration of a subducted slab provided the Cu mineralization in southern Hunan Province.
This study describes the fractal dimensions of the spatial distributions of lineaments as an index of the complexity of faults, and the results could provide new insights into the migration of ore-bearing fluid. The Segment Tracing Algorithm method is employed to extract the lineaments in northeast Yunnan Province from a remote sensing image. Box-counting fractal and multifractal models are used to analyze the fractal and multifractal spatial distribution characteristics of the linear structures. The different directions of the linear structure fractal dimensions are similar in the study area. The fractal dimensions of all lineaments, northeast trending lineaments and northwest trending lineaments are 1.98, 1.94 and 1.95, respectively. The dimensions of four large ore deposit fields, Kuangshanchang, Qilinchang, Maozu, and Lemachang, are 1.93, 1.92, 1.95, and 1.93, respectively. The fractal dimensions of these four fields are greater than those of the South China lineaments. The super-large and large ore deposits are consistent with fractal dimensions with high values. The scale index and the singular index show nonlinear relationships with any real number, and the fractal dimension spectrum has a unimodal curve. This study provides a useful reference for deposit exploration in areas with topographies similar to that in northeastern Yunnan.
East Asia has long been recognized as a major center for temperate woody plants diversity. Although several theories have been proposed to explain how the diversity of these temperate elements accumulated in the region, the specific process remains unclear. Here we describe six species of Carpinus, a typical northern hemisphere temperate woody plant, from the early Miocene of the Maguan Basin, southwestern China, southern East Asia. This constitutes the southernmost, and the earliest occurrence that shows a high species diversity of the genus. Together with other Carpinus fossil records from East Asia, we show that the genus had achieved a high diversity in East Asia at least by the middle Miocene. Of the six species here described, three have become extinct, indicating that the genus has experienced apparent species loss during its evolutionary history in East Asia. In contrast, the remaining three species closely resemble extant species, raising the possibility that these species may have persisted in East Asia at least since the early Miocene. These findings indicate that the accumulation of species diversity of Carpinus in East Asia is a complex process involving extinction, persistence, and possible subsequent speciation.