Anatomy of a eustatic event during the Turonian (Late Cretaceous) hot greenhouse climate

Sequence stratigraphic studies consider relative change in sea level (as regulated by eustasy, local tectonics and sediment supply) as the main builder of the stratigraphic record. Eustasy has generally been considered as a consequence of the growth and decay of continental ice sheets that would explain large, rapid changes in sea level, even during periods of relative global climatic warmth. However, such a mechanism has become increasingly difficult to envision during times of extreme global warmth such as the Turonian, when the equator-to-pole temperature gradient was very low and the presence of polar ice seems improbable. This paper investigates the timing and extent of sea level falls during the late Cenomanian through Turonian, especially the largest of those events, sequence boundary KTu4, which occurred during the middle to late Turonian peak of the Cretaceous hot greenhouse climate. We conclude that the amplitude of the widespread third-order sea level fall in the middle Turonian that is centered at ~91.8 Ma varies at different locations depending on the influence of dynamic topography on local tectonics and regional climatic conditions. Ice volume variations seem unlikely as a mechanism for controlling sea level at this time. However, this causal factor cannot be ruled out completely since Antarctic highlands (if they existed in the Late Cretaceous) could sequester enough water as ice to cause eustatic falls. To ascertain this requires detailed tomographic imaging of Antarctica, followed by geodynamic modeling, to determine whether high plateaus could have existed to accumulate ephemeral ice sheets. Other mechanisms for sea level change, such as transference between ground water (a small amplitude shorter time scale effect) and the ocean and entrainment and release of water from the mantle to the oceanic reservoir (a potentially large amplitude and longer time scale process), are intriguing and need to be explored further to prove their efficacy at third-order time scales.     

Quantifying the impact of climate variables on reference evapotranspiration in Pearl River Basin,China

ABSTRACT

The impact of climate variables on monthly reference evapotranspiration (ET_o) is a critical issue in water resources management and irrigation planning. The spatio-temporal contribution of climate variables to ET_o in the Pearl River Basin (PRB), China, from 1960 to 2016 were calculated based on sensitivity and relative change of each climatic variable. The results show that annual ET_o total decreased by 1.64% and diminished in magnitude from the southeast to the northwest. Sunshine duration, wind speed and relative humidity decreased by 15.5%, 7.4%, and 4.0%, respectively, while average temperature increased by 4.25%. The ET_o showed a positive sensitivity to all variables except relative humidity, which showed a negative sensitivity. Sunshine duration had the highest contribution of ?4.26%, and the overall decrease in ET_o was mainly caused by the declines in sunshine duration and wind speed, which offset the positive impact of rises in average temperature and reduction in relative humidity.     

Permian felsic magmatism in the Neoproterozoic Nagar Parkar Igneous Complex of the Malani Igneous Suite: Evidence from zircon U–Pb age

We report Permian (ca. 272 Ma ±5.4 Ma) felsic dykes that intrude into the Neoproterozoic (ca. 750 Ma) magmatic suite of the Nagar Parkar Igneous Complex (NPIC), the western extension of the Malani Igneous Suite (MIS). The NPIC consists of Neoproterozoic basement amphibolites and granites (riebeckite–aegirine gray granites and the biotite–hornblende pink granites), all of which are intruded by several generations of mafic and felsic dykes. Granitic magmatism occurred in the Late Neoproterozoic (ca. 750 Ma) due to the subduction‐, followed by the rift‐related tectonic regime during the breakup of the Rodinia supercontinent. U–Th–Pb zircon and monazite CHIME age data of 700–800 Ma from the earlier generation porphyritic felsic dykes suggest the dyke intrusion was coeval or soon after the emplacement of the host granites. Our findings of Permian age orthophyric felsic dykes provide new insights for the prevalence of active tectonics in the MIS during late Paleozoic. Textural features and geochemistry also make the orthophyric dykes distinct from the early‐formed porphyritic dykes and the host granites. Our newly obtained age data combined with geochemistry, suggest the existence of magmatism along the western margin of India (peri‐Gondwana margin) during Permian. Like elsewhere in the region, the Permian magmatism in the NPIC could be associated with the rifting of the Cimmerian micro‐continents from the Gondwana.     

Long-term analysis of measured and simulated evapotranspiration and soil water content

In our study, we analysed a period from 2003 to 2012 with micrometeorological data measured at a boundary-layer field site operated by the Lindenberg Meteorological Observatory – Richard-Aßmann-Observatory of the German Meteorological Service (DWD). Amongst others, these data consist of real evapotranspiration (ETr) rates measured by eddy covariance and soil water contents determined by time domain reflectometry. Measured ETr and soil water contents were compared with those simulated by a simple soil–vegetation–atmosphere transfer (SVAT) scheme consisting of the FAO56 Penman-Monteith equation and the soil water flux model Hydrus-1D. We applied this SVAT scheme using uncompensatory and compensatory root water uptake (RWU). Soil water contents and ETr rates calculated using uncompensatory RWU showed an acceptable fit to the measured ones. In comparison, the use of compensatory RWU resulted in lower model performance due to higher deviations between measured and simulated soil moisture values and ETr rates during dry summer periods.     

A new type of isotopic anomaly in shergottite sulfides

The isotopic composition and abundance of sulfur in extraterrestrial materials are of interest for constraining models of both planetary and solar system evolution. A previous study that included phase‐specific extraction of sulfur from 27 shergottites found the sulfur isotopic composition of the Martian mantle to be similar to that of terrestrial mid‐ocean ridge basalts, the Moon, and nonmagmatic iron meteorites. However, the presence of positive Δ³³S anomalies in igneous sulfides from several shergottites, indicating incorporation of atmospherically processed sulfur into the subsurface, complicated this interpretation. The current study expands upon the previous work through analyses of 20 additional shergottites, enabling tighter constraints on the isotopic composition of juvenile Martian sulfur. The updated composition (δ³⁴S = ?0.24 ± 0.05‰, Δ³³S = 0.0015 ± 0.0016‰, and Δ³⁶S = 0.039 ± 0.054‰, 2 s.e.m.), representing the weighted mean for all shergottites within the combined population of 47 without significant Δ³³S anomalies, strengthens our earlier result. The presence of sulfur isotopic anomalies in igneous sulfides of some meteorites suggests that their parent magmas may have assimilated crustal material. We observed small negative Δ³³S anomalies in sulfides from two meteorites, NWA 7635 and NWA 11300. Although negative Δ³³S anomalies have been observed in nakhlites and ALH 84001, previous anomalies in shergottites have all shown positive values of Δ³³S. Because NWA 7635 has formation age of 2.4 Ga and is much more ancient than shergottites analyzed previously, this finding expands our perspective on the continuity of Martian atmospheric sulfur photochemistry over geologic time.     

Antiproliferative and apoptosis-inducing potential of 3β-hydroxy-△5-steroidal congeners purified from the soft coral Dendronephthya putteri

The exploration and identification of antiproliferative phytochemicals have received increased attention in medicinal chemistry.In particular,research focused on the toxicology of marine natural products has increased in recent years.Terpenoids,among many secondary metabolites,have been demonstrated to act as effective anticancer agents.Soft corals,a group of marine invertebrates,produce a variety of terpenoids with biofunctional properties.The current study presents the extraction,purification,and identification of sterol congeners from the soft coral Dendronephthya putteri.The method involves 50%chloro form-methanol extraction,polar column fractionation,and analy sis through GC-MS~n.Do se-dependent antiproliferative activity was observed within the sterol-rich fraction(DPCMH 2-4),which consisted of3β-hydroxy-A5-steroidal congeners.This fraction inhibited the growth of HL-60 and MCF-7 cells with IC_(50) values of 25.27±1.43 and 22.81±0.15 μg/mL,respectively.Apoptotic body formation,DNA damage,cell cycle arrest,and apoptotic cell signaling pathway activation were also observed,reinforcing the dosedependent antiproliferative and apoptosis-inducing activity of 3β-hydroxy-A5-steroidal congeners.To our knowledge,this is the first report of anticancer agent identification from the soft coral D.putteri.Based on the observations,these steroidal congeners are promising candidates for the development of anticancer drugs.     

Estimation of daily space–time precipitation series for macroscale hydrological modelling

An important problem in modelling macroscale basins, especially for sparsely observed regions, is the lack of precipitation information. Alternatives to using straightforward interpolated surface observations include the utilization of more advanced interpolation techniques and the use of additional precipitation information from atmospheric models. Conventional and geostatistical methods are applied for optimal interpolation and assimilation of observed and model precipitation. Various time-series of daily areal precipitation distributions are produced and compared using not only an internal precipitation validation, but also an objective verification based on stream flow simulations. The Mackenzie River Basin in north-western Canada is used as the study area and hydrological simulations are carried out with the model SLURP. It was found that better interpolation techniques and the use of combined precipitation data can improve the hydrological simulations and that the enhancements are related to the relative size of the simulation units used. © 1998 John Wiley & Sons, Ltd.     

Dietary pattern recognition on Twitter: a case example of before,during, and after four natural disasters

Natural Hazards - Little is known about what foods/beverages (F&B) are common during natural disasters. The goal of this study was to track high-frequency F&B mentions during four...     

The Herbig Be Star IL Cep A as a Long-Periodic Spectroscopic Binary

The results of long-term spectral monitoring of the Herbig Be star IL Cep A are presented. A smooth variation in the parameters of the Нα and Нβ line emission component has been discovered. The helium absorption lines He I λ4922 and 5876 Å show seasonal changes, however, these changes do not correlate with changes in hydrogen emission. The radial velocities of the narrow lines D Na I and DIB λ5780, 5796 Å correspond to that of the interstellar medium. The hydrogen emission lines are apparently formed in a triple system, including a close pair of B stars and a remote low-mass K–A component. The orbital elements of this system were calculated using an approximate spectral binary model, where a close pair of massive B stars was considered as one massive component. The rationale for this approach for determining the elements of the orbit is given. The orbital period P = 3550 ± 28 days is determined and some other parameters of the orbit are estimated.     

Characterization of Mechanisms and Processes Controlling Groundwater Recharge and its Quality in Drought-Prone Region of Central India (Buldhana,Maharashtra) Using Isotope Hydrochemical and End-Member Mixing Modeling

A thorough study on understanding of groundwater recharge sources and mechanisms was attempted by integrating the hydrogeological, geochemical and isotopic information along with groundwater dating and end-member mixing analysis (EMMA). This study was necessitated due to prolonged dryness and unavailability of freshwater in semi arid Deccan trap regions of Central India. In addition, groundwater resources are not characterized well in terms of their geochemical nature and recharge sources. The hydrogeochemical inferences suggest that aquifer I consists of recently recharged water dominated by Ca–Mg–HCO₃ facies, while groundwater in aquifer II shows water–rock interaction and ion exchange processes. Presence of agricultural contaminant, nitrate, in both aquifers infers limited hydraulic interconnection, which is supported by unconfined to semi-confined nature of aquifers. Groundwater in both aquifers is unsaturated with respect to carbonate and sulfate minerals indicating lesser water–rock interaction and shorter residence time. This inference is corroborated by tritium age of groundwater (aquifer I: 0.7–2 years old and aquifer II: 2–4.2 years old). Stable water isotopes (δ²H, δ¹⁸O) suggest that groundwater is a mixture of rainwater and evaporated water (surface water and irrigation return flow). EMMA analysis indicates three groundwater recharge sources with irrigation return flow being the dominant source compared to others (rainwater and surface waters). A conceptual model depicting groundwater chemistry, recharge and dynamics is prepared based on the inferences.