Influences of Climate Change and Human Activities on NDVI Changes in China

The spatiotemporal evolution of vegetation and its influencing factors can be used to explore the relationships among vegetation, climate change, and human activities, which are of great importance for guiding scientific management of regional ecological environments. In recent years, remote sensing technology has been widely used in dynamic monitoring of vegetation. In this study, the normalized difference vegetation index (NDVI) and standardized precipitation‒evapotranspiration index (SPEI) from 1998 to 2017 were used to study the spatiotemporal variation of NDVI in China. The influences of climate change and human activities on NDVI variation were investigated based on the Mann–Kendall test, correlation analysis, and other methods. The results show that the growth rate of NDVI in China was 0.003 year−1. Regions with improved and degraded vegetation accounted for 71.02% and 22.97% of the national territorial area, respectively. The SPEI decreased in 60.08% of the area and exhibited an insignificant drought trend overall. Human activities affected the vegetation cover in the directions of both destruction and restoration. As the elevation and slope increased, the correlation between NDVI and SPEI gradually increased, whereas the impact of human activities on vegetation decreased. Further studies should focus on vegetation changes in the Continental Basin, Southwest Rivers, and Liaohe River Basin.

Paleoenvironment Implication of Red Paleosols in a Late Cretaceous Continental Succession, Songliao Basin, NE China

The limited knowledge of Late Cretaceous terrestrial environments and their response to tectonic events in mid-latitudes can be addressed through continental basin deposits such as paleosols. Paleosols have been discovered in the Late Cretaceous Yaojia Formation in the southern Songlaio Basin and are recognized by evidence of soil structures controlled by pedogenesis. Sedimentary facies research on red paleosols was conducted on the Late Cretaceous Yaojia Formation in the outcrop of the southern Songliao Basin to interpret the depositional environments and tectonic significance of red paleosols during the greenhouse period. Mudflat, lake margin, and shallow lake depositional environments in a semi-arid climate are interpreted from the outcrops based on sedimentary descriptions and interpretation as well as geochemical and micromorphological analyses of paleosols in outcrops. We reconstructed the paleoenvironmental and paleoclimatic conditions through the paleosols in the mudflats and lake margin. The red paleosols in the mudflats and lake margin deposits formed in a stable landscape influenced by the tectonic uplift of the Songliao Basin, which is considered as new important evidence for tectonic uplift influenced by the collision of the Okhotomorsk Block with East Asia. The tectonic uplift process in East Asia is identified from the evolution of the depositional environments and drainage conditions inferred from different types of paleosols. Thus, the paleosols-bearing red bed deposits in outcrops provide an important contribution of the Late Cretaceous terrestrial paleoclimate and the tectonic setting research.

Advances in the Hydraulic Interpretation of Water Wells Using Flowmeter Logs

This paper reports on the methodology developed for a new hydraulic interpretation of flowmeter logs, allowing a better characterization of continental hydrological basins. In the course of a flowmeter log, different flow stretches are established mostly corresponding to permeable layers (aquifers), among which there are other stretches mainly corresponding to less permeable layers (aquitards). In such hydrological basins of sufficient thickness, these flow stretches may not have the same hydraulic head. This fact brings about the need for a new hydraulic interpretation that provides the actual distribution of horizontal permeability throughout the aquifer at depth. The modified hydraulic interpretation developed in this study focuses on the differences of the effective pressure gradient (considered as the difference between the hydraulic head in the well and the hydraulic head of each stretch) experienced by the different flow stretches along the well, due to the existence of different hydraulic heads. The methodology has been developed starting from a water well located in a multilayered aquifer within the so-named Madrid Basin (the NW part of the continental basin of the Tajo River), located in the centre of the Iberian Peninsula. In this well, a step-drawdown pumping test was conducted, in which the pumping rate versus drawdown and the specific capacity versus drawdown showed discrepancies with Darcian behaviour and an exponent of the Jacob equation of less than 1. Flowmeter logs were then recorded for different discharge rates and pump depths; the resulting water input from deeper permeable layers did not appear to show the expected relation with respect to drawdown. With the proposed methodology the results comply with the expected linearity and the cited discrepancies are solved.

GPR signature of Quaternary faulting: a study from the Mt. Pollino region, southern Apennines, Italy

With the aim of unveiling evidence of Late Quaternary faulting, a series of Ground Penetrating Radar (GPR) profiles were acquired across the Campotenese continental basin (Mt. Pollino region) in the southern Apennines active extensional belt (Italy). A set of forty-nine 300 MHz and 500 MHz GPR profiles, traced nearly perpendicular to a buried normal fault, were acquired and carefully processed through a customized workflow. The data interpretation allowed us to reconstruct a pseudo-3D model depicting the boundary between the Mesozoic bedrock and the sedimentary fill of the basin, which were in close proximity to the fault. Once reviewing and defining the GPR signature of faulting, we highlight in our data how near surface alluvial and colluvial sediments appear to be dislocated by a set of conjugate (west and east-dipping) discontinuities that penetrate inside the underlying Triassic dolostones. Close to the contact between the continental deposits and the bedrock, some buried scarps which offset wedge-shaped deposits are interpreted as coseismic ruptures, subsequently sealed by later deposits. Although the use of pseudo-3D GPR data implies more complexity linking the geophysical features among the radar images, we have reconstructed a reliable subsurface fault pattern, discriminating master faults and a series of secondary splays. We believe our contribution provides an improvement in the characterization of active faults in the study area which falls within the Pollino seismic gap and is considered potentially prone to severe surface faulting. Our aim is for our approach and workflow to be of inspiration for further studies in the region as well as for similar high seismic hazard areas characterized by scarcity of near-surface data.

Origin and evolution of unconformities in a continental rift basin: a case study from the Lishu Depression in Songliao Basin, China

A variety of unconformity types are commonly developed during the rifting of a continental basin. Identifying their origin and evolution is prerequisite to understanding the complex tectono-sedimentary evolution of the basin and to evaluate the basin’s oil and gas resources. Based on the 2D/3D seismic, geophysical logging, and subsurface lithological data, the unconformities within the rift layer of the Lishu Depression in the Songliao Basin are identified as disconformities, nonconformities and four ‘types’ of angular unconformities. Their evolution and origin are analyzed by associating the unconformities with the basin’s tectonic evolution. The results show that the rifting of the Lishu Depression was not a continuous process. Instead, several regional tectonic episodes influenced the basin’s evolution. Episodic compressional events and a phase of extension along the main faults determined the basin configuration and sedimentary fill characteristics of different sub-rifting stages. The tectonic history and related paleogeomorphology changes are the dominant factors in the formation of these different unconformity types. During the rifting process, the type and distribution of unconformity varied. In the initial rifting stage, the basin developed a nonconformity and four types of angular unconformities as the result of both regional uplift and fault block tilt. Rotation and tilting of the fault blocks during the intensive rifting resulted in two types of angular unconformities. Finally, in the recession rifting stage, a different form of angular unconformity and disconformity developed, mainly as a result of the regional uplift and subsequent subsidence.

Phylogenomics of Piranhas and Pacus (Serrasalmidae) Uncovers How Dietary Convergence and Parallelism Obfuscate Traditional Morphological Taxonomy

The Amazon and neighboring South American river basins harbor the world’s most diverse assemblages of freshwater fishes. One of the most prominent South American fish families is the Serrasalmidae (pacus and piranhas), found in nearly every continental basin. Serrasalmids are keystone ecological taxa, being some of the top riverine predators as well as the primary seed dispersers in the flooded forest. Despite their widespread occurrence and notable ecologies, serrasalmid evolutionary history and systematics are controversial. For example, the sister taxon to serrasalmids is contentious, the relationships of major clades within the family are inconsistent across different methodologies, and half of the extant serrasalmid genera are suggested to be non-monophyletic. We analyzed exon capture to reexamine the evolutionary relationships among 63 (of 99) species across all 16 serrasalmid genera and their nearest outgroups, including multiple individuals per species to account for cryptic lineages. To reconstruct the timeline of serrasalmid diversification, we time-calibrated this phylogeny using two different fossil-calibration schemes to account for uncertainty in taxonomy with respect to fossil teeth. Finally, we analyzed diet evolution across the family and comment on associated changes in dentition, highlighting the ecomorphological diversity within serrasalmids. We document widespread non-monophyly of genera within Myleinae, as well as between Serrasalmus and Pristobrycon, and propose that reliance on traits like teeth to distinguish among genera is confounded by ecological homoplasy, especially among herbivorous and omnivorous taxa. We clarify the relationships among all serrasalmid genera, propose new subfamily affiliations, and support hemiodontids as the sister taxon to Serrasalmidae. [Characiformes; exon capture; ichthyochory; molecular time-calibration; piscivory.]

Hyperpycnal flow depositional characteristics and model in an ancient continental basin: a record from the Oligocene Lower Huagang Formation in the Xihu Sag, East China Sea Shelf Basin

Modern observations have determined the presence of hyperpycnal flows; however, their presence in ancient rocks is scarcely reported in the literature, particularly with respect to continental strata. The present study is the first to use core and thin-section analyses and examination of physical reservoir properties to identify hyperpycnal flow sediment from the lower section of the Oligocene Huagang Formation in the central Xihu Sag, East China Sea Shelf Basin. The multiple fine sandy layers are characterized by lower reverse-graded and upper normal-graded bedding with horizontal bedding, climbing-ripple lamination, wavy bedding, and small foreset laminae. Microerosion surfaces are occasionally present between the reverse-graded and normal-graded bedding, and plant fragments are sometimes visible in the deposits. The same grain size sequence changes are observed in the thin sections. This lithologic combination is considered to be related to hyperpycnal flow sedimentation caused by flood events. The lower reverse-graded and upper normal-graded bedding sequences indicate that the flood energy first increased then decreased and the microerosion surfaces were formed through erosion of lower sediments by the flood. Hyperpycnal flows can directly transport deposits from an estuary to a deep-water basin, which distinguishes them from typical turbidity currents. This study also establishes a sedimentary model of the hyperpycnal flow in lacustrine basin, which can be used as a reference for future hyperpycnal deposit studies.