Dataset Information

Conversion of tectonic and climatic forcings into records of sediment supply and provenance.

ABSTRACT: Understanding how environmental forcings (e.g., tectonics, climate) are transformed by erosional landscapes into sedimentary signals is a critical component of inverting the stratigraphic record. Previous research has largely focused on sediment supply (Q_s) and grain size as the de facto sedimentary signals of changing forcing mechanisms. We use a numerical model to consider the paired response of sediment provenance (P_v), expressed as fractional sediment load, and Q_s to demonstrate that the same change in environmental forcing may have a different expression in the sedimentary record. While Q_s reflects integrated denudation across an erosional catchment, P_v is controlled by spatially variable erosion that occurs in transient landscapes. P_v from proximal sediment sources increases during upstream knickpoint migration, whereas P_v from distal sediment sources increases when bedrock channels incise to produce lower gradient profiles. Differences between the Q_s and P_v signals relate to distinct geomorphic processes that operate on different time scales and allow for a refined differentiation of the timing and mechanism of forcings than possible via analysis of either signal alone. Future efforts to integrate multiple sedimentary signals may thus yield a richer picture of underlying forcing mechanisms, facilitating efforts to invert the stratigraphic record.

SUBMITTER: Sharman GR

PROVIDER: S-EPMC6411995 | biostudies-literature | 2019 Mar

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Conversion of tectonic and climatic forcings into records of sediment supply and provenance.

Sharman Glenn R GR Sylvester Zoltan Z Covault Jacob A JA

Scientific reports 20190311 1

Understanding how environmental forcings (e.g., tectonics, climate) are transformed by erosional landscapes into sedimentary signals is a critical component of inverting the stratigraphic record. Previous research has largely focused on sediment supply (Qs) and grain size as the de facto sedimentary signals of changing forcing mechanisms. We use a numerical model to consider the paired response of sediment provenance (Pv), expressed as fractional sediment load, and Qs< ...[more]

PMID: 30858447

Similar Datasets

Project description:This is a systematic attempt to depict the genetic evolution of the Late Quaternary sediments of the southeastern (SE) coastal region of the Bengal basin regarding paleotectonic settings, sedimentation, provenance, paleo-climatic conditions, weathering condition and age. The study has considered multiple attributes such as, lithology/lithofacies, sedimentary features/records, major oxides, clay minerals, foraminifera, and radiocarbon dating. The lithological characters along with associated clay minerals confirmed that a Pleistocene paleosol horizon (over-bank deposits) of warm-humid nature is commonly encountered immediately on top of the sub-crop bed-rock in the area overlain by Holocene fluvio-marine sediments of the same nature. The lithofacies, foraminiferal assemblages, and sedimentary structures of the analyzed samples suggest that the Holocene sediments have been presumably deposited in a fluvio-marine condition after the Last Glacial Maximum (LGM) due to the transgression of the sea. Geochemically, the sediments are classified as Fe-rich shale, shale, and wake and primarily intermediate to felsic orogen provenance. These are possibly derived from intense weathered sources from the upheaval of Himalayan ranges of both active continental margin and Island Arc paleotectonic setting. The plot of the Index of Compositional Variability versus the Chemical Index of Alteration indicates that the sediments seemingly experienced intense weathering associated with warm and humid climatic conditions. The sedimentation rates of the area vary from place to place and layer to layer due to the complex delta-building process. The reconstructed Relative Sea Level Curve reveals that presumably, the sea level has reached its current position after the LGM. The deduction possibly will facilitate the (1) reconstruction of Late Quaternary coastal evolution after LGM, (2) support for future urbanization, land use plans, etc., and (3) also be helpful for international researchers to understand the possible sources of sediment input in the area from the complex interplay of the Indian-, Eurasian- and Myanmar-plates.

Project description:AimWe test for spatial and climatic patterns of diversification in the Orchidaceae, an angiosperm family characterized by high levels of species diversity and rarity. Globally, does orchid diversity correlate with land area? In Australia, does diversity correlate with herbarium collecting effort, range size, or climate niche breadth? Where are Australia's orchids distributed spatially, in protected areas, and in climate space?LocationGlobal, then Australia.MethodsWe compared orchid diversity with land area for continents and recognized orchid diversity hotspots. Then, we used cleaned herbarium records to compare collecting effort (for Australian Orchidaceae vs. all other plant families, and also among orchid genera). Spatial and climate distributions were mapped to determine orchids' coverage in the protected area network, range sizes, and niche breadths.ResultsGlobally, orchid diversity does not correlate with land area (depauperate regions are the subantarctic: 10 species, and northern North America: 394 species). Australian herbarium records and collecting effort generally reflect orchid species diversity (1,583 spp.), range sizes, and niche breadths. Orchids are restricted to 13% of Australia's landmass with 211 species absent from any protected areas. Species richness is the greatest in three biomes with high general biodiversity: Temperate (especially southwest and southeast Australia), Tropical, and Subtropical (coastal northern Queensland). Absence from the Desert is consistent with our realized climate niche-orchids avoid high temperature/low rainfall environments. Orchids have narrower range sizes than nonorchid species. Highly diverse orchid genera have narrower rainfall breadths than less diverse genera.Main conclusionsHerbarium data are adequate for testing hypotheses about Australian orchids. Distribution is likely driven by environmental factors. In contrast, diversification did not correlate with increases in range size, rainfall, or temperature breadths, suggesting speciation does not occur via invasion and local adaptation to new habitats. Instead, diversification may rely on access to extensive obligate symbioses with mycorrhizae and/or pollinators.

Project description:Settlement crises in ancient cultures of Western Asia are commonly thought to be caused by climatic events such as severe droughts. However, the insufficient climate proxy situation in this region challenges the inference of clear relationships between climate and settlement dynamics. We investigate the Holocene climatic changes on the Varamin Plain in the context of the climatic history of Western Central Asia by using a transient comprehensive Earth System Model simulation (8 ka BP to pre-industrial), a high-resolution regional snapshot simulation and a synthesis of pollen-based climate reconstructions. In line with the reconstructions, the models reveal only slightly varying mean climatic conditions on the Varamin Plain but indicate substantial changes in seasonality during the Holocene. Increased precipitation during spring, combined with lower temperature and potentially stronger snow accumulation on the upstream Alborz mountains may have led to an increased water supply on the alluvial fan during the vegetation period and thus to more favourable conditions for agricultural production during the Mid-Holocene compared to modern times. According to the model, dry periods on the Central Iranian Plateau are related to particularly weak Westerly winds, fostering the subsidence in the mid-troposphere and hampering precipitation over the region. The model reveals that dry periods have spatially heterogenous manifestations, thus explaining why they do not appear in all proxy records in the wider study region. In fact, the climatic signal may depend on local environmental conditions. The interaction of the topography with the atmospheric circulation leads to additional spatial heterogeneity. Although our results provide several indications for a connection between climate and settlement dynamics, the small overall changes in moisture call into question whether climate is the main driver for settlement discontinuities on the Central Iranian Plateau. To shed further light on this issue, more high-resolution long-term proxy records are needed.

Dataset Information

Conversion of tectonic and climatic forcings into records of sediment supply and provenance.

Publications

Conversion of tectonic and climatic forcings into records of sediment supply and provenance.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets