No abstract

We carried out a paleomagnetic investigation on Permian volcanic rocks from central eastern Inner Mongolia, NE China, in order to identify the paleoposition of the North China and Songliao‐Xilinhot blocks during Permo‐Carboniferous times and thereby define the spatial‐temporal history of the eastern Paleo‐Asian Ocean (PAO). Two prefolding magnetization components were isolated from the Sanmianjing and Elitu Formations (~283–266 Ma) along the northern margin of North China block (NMNCB) and the Dashizhai Formation (~280 Ma) in the Songliao‐Xilinhot block (SXB). These two results suggest paleolatitudes of ~4.9°N for the SXB and ~22.3°N for the NMNCB. Previously published results are classified according to recently proposed models and evaluated for the influence of inclination shallowing. Combined with earlier multidisciplinary studies, we propose a tentative paleogeographic reconstruction model for the eastern Central Asian Orogenic Belt (CAOB) during the Late Carboniferous to Early Triassic times. Siberia was situated at middle‐high paleolatitudes (~45°–65°N), and the Central Mongolia‐Erguna and South Mongolia‐Xing'an blocks had a middle latitude (~30°–45°N) from the Late Carboniferous to Early Permian. By the Late Permian to Early Triassic (~250 Ma), there was no significant latitudinal difference between the eastern CAOB blocks. Final closure of the eastern PAO along both the Hegenshan‐Heihe and Solonker sutures took place followed by the formation of Cinamuria.

The tectonic blocks that comprise present-day East Asia were amalgamated with Laurussia following the final closure of the Paleo-Asian and Paleo-Tethys oceans in late Paleozoic and Mesozoic times. These events allowed Pangea to reach its maximum packing at 220 Ma prior to supercontinent breakup . Quantifying the movement history of blocks surrounding the Paleo-Asian Ocean (PAO) can provide better understanding on the spatial-temporal evolution of the PAO and shed light on the paleogeography of East Asian blocks during the formation of Pangea.The timing of the PAO's final closure is contentious. Models based primarily on geological evidence (sedimentology, structural geology, metamorphism, provenance analyses, paleobiogeography, petrogeochemistry of igneous rocks, and ophiolites) can be broadly categorized into two end-member groups: (a) Middle-Late Devonian closure mainly supported by two middle Paleozoic orogenic belts recognized near the Solonker and Hegenshan sutures as well as overlying Late Devonian unconformities (e.g.,

Floral color polymorphism can provide great insight into species evolution from a genetic and ecological standpoint. Color variations between species are often mediated by pollinators and are fixed characteristics, indicating their relevance to adaptive evolution, especially between plants within a single population or between similar species. The orchid genus Pleione has a wide variety of flower colors, from violet, rose-purple, pink, to white, but their color formation and its evolutionary mechanism are unclear. Here, we selected the P. limprichtii population in Huanglong, Sichuan Province, China, which displayed three color variations: Rose-purple, pink, and white, providing ideal material for exploring color variations with regard to species evolution. We investigated the distribution pattern of the different color morphs. The ratio of rose-purple:pink:white-flowered individuals was close to 6:3:1. We inferred that the distribution pattern may serve as a reproductive strategy to maintain the population size. Metabolome analysis was used to reveal that cyanindin derivatives and delphidin are the main color pigments involved. RNA sequencing was used to characterize anthocyanin biosynthetic pathway-related genes and reveal different color formation pathways and transcription factors in order to identify differentially-expressed genes and explore their relationship with color formation. In addition, qRT-PCR was used to validate the expression patterns of some of the genes. The results show that PlFLS serves as a crucial gene that contributes to white color formation and that PlANS and PlUFGT are related to the accumulation of anthocyanin which is responsible for color intensity, especially in pigmented flowers. Phylogenetic and co-expression analyses also identified a R2R3-MYB gene PlMYB10, which is predicted to combine with PlbHLH20 or PlbHLH26 along with PlWD40-1 to form an MBW protein complex (MYB, bHLH, and WDR) that regulates PlFLS expression and may serve as a repressor of anthocyanin accumulation-controlled color variations. Our results not only explain the molecular mechanism of color variation in P. limprichtii, but also contribute to the exploration of a flower color evolutionary model in Pleione, as well as other flowering plants.

Determining the presence or absence of a past long-lived lunar magnetic field is crucial for understanding how the Moon’s interior and surface evolved. Here, we show that Apollo impact glass associated with a young 2 million–year–old crater records a strong Earth-like magnetization, providing evidence that impacts can impart intense signals to samples recovered from the Moon and other planetary bodies. Moreover, we show that silicate crystals bearing magnetic inclusions from Apollo samples formed at ∼3.9, 3.6, 3.3, and 3.2 billion years ago are capable of recording strong core dynamo–like fields but do not. Together, these data indicate that the Moon did not have a long-lived core dynamo. As a result, the Moon was not sheltered by a sustained paleomagnetosphere, and the lunar regolith should hold buried 3He, water, and other volatile resources acquired from solar winds and Earth’s magnetosphere over some 4 billion years.