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Engineering rice to perform better under dynamic light regimes

Jennifer Quebedeaux

and 4 more

January 29, 2024
Light levels change throughout the day, are affected by climate and weather, and
are filtered by the local environment. Switching between low and high levels of
light over varying periods of time experienced by an organism in its environment
shapes the tempo and mode of its light detection system. Plants must respond to
dynamic environmental conditions and thus switch between efficient
photosynthesis and photoprotection. Receptors on the plasma membrane perceive
extracellular signals, such as photosynthetically-fixed sugars, are coupled to
cytoplasmic G proteins to transduce information to cytoplasmic proteins and to
amplify that signal to bring about changes like photosynthetic efficiency in
both short (e.g. enzymatic reactions) and long (e.g. plant development) time
scales. While G proteins have been shown to be important in regulating various
aspects of stomata and photosynthesis, their role has yet to be fully
understood. A regulator of G signaling (RGS) has been shown to sense sugars
fixed in photosynthesis. Thus, we hypothesize that RGS mediates responses to
dynamic light. The sequenced genomes within the grass family are the only
genomes throughout Plantae known to lack RGS. By contrast, Setaria retains the
RGS gene. Thus, the RGS gene from Setaria was expressed in rice to better
understand the function of RGS. In this study, multiple transgenic events were
grown to investigate their phenotypic response. We identified lines with altered
stomatal patterning and rates of stomatal closure in response to changing light
levels that will be used in future experiments.
Progression of Ocean Interior Acidification over the Industrial Era

Jens Daniel Müller

and 1 more

January 29, 2024
Ocean acidification driven by the uptake of anthropogenic CO2 represents a major
threat to ocean ecosystems, yet little is known about its progression beneath
the surface. Here, we reconstruct the history of ocean interior acidification
(OIA) from 1800 to 2014 on the basis of observation-based estimates of the
accumulation of anthropogenic carbon. Across the top 100 m and over the
industrial era, the saturation state of aragonite (Ωarag) and pH = -log[H+]
decreased by more than 0.6 and 0.1, respectively, with a progress of nearly 50%
over the last 20 years (1994-2014). While the magnitude of the Ωarag change
decreases uniformly with depth, the magnitude of the pH decrease exhibits a
distinct maximum in the upper thermocline. Since 1800, the saturation horizon
(Ωarag=1) shoaled by more than 200 m, approaching the euphotic zone in several
regions, especially in the Southern Ocean, and exposing many organisms to
corrosive conditions.
Controls on Exchange through a Tidal Mixing Hotspot at an Estuary Constriction

Susan E. Allen

and 4 more

January 29, 2024
A version of This Work has been submitted to _J. Physical Oceanography_ This
Work has not yet been peer-reviewed and is provided by the contributing
Author(s) as a means to ensure timely dissemination of scholarly and technical
Work on a noncommercial basis. Copyright and all rights therein are maintained
by the Author(s) or by other copyright owners. It is understood that all persons
copying this information will adhere to the terms and constraints invoked by
each Author’s copyright. This Work may not be reposted without explicit
permission of the copyright owner. Copyright in this Work may be transferred
without further notice. ABSTRACT Deep estuaries are often separated from the
open ocean by sills and constrictions. These constrictions are areas of intense
mixing often dominating the total estuarine mixing. The amount and depth of the
estuarine exchange depends sensitively on the mixing and the densities of the
waters on the two sides of the mixing region. Thus, the density, nutrient
concentration, oxygen saturation, and dissolved inorganic carbon content of the
incoming estuarine flow depend on local tidal mixing processes and large scale
buoyancy dynamics. We have investigated this process using a numerical model
(SalishSeaCast) of the Salish Sea on the West Coast of North America, straddling
the Canada/USA border. The region receives considerable freshwater dominated by
the outflow of the Fraser River. The Fraser River first flows into the deep
Strait of Georgia but the freshwater must traverse the strongly tidally mixed
shallower passages through the Gulf/San Juan Islands before it reaches the
Pacific Ocean. The model correctly reproduces the deep water flow into the
Strait of Georgia as evaluated against Ocean Networks Canada (ONC) four
bottom-mounted, continuously recording, conductivity-temperature instruments
which capture this incoming flow. Using a four-year hindcast from the model we
determine the amount, depth and position of the outflow and inflow. We show that
95% of the variance of the 4-day average baroclinic flux through the tidal
mixing region can be explained by the density difference across the region and a
Richardson Number based on the tidal velocities. The outgoing flux includes both
surface and intermediate waters and the incoming flux includes both intermediate
and deep waters. Laterally, fluxes into and out of the Strait of Georgia and
across Victoria Sill show the impact of the Coriolis force and local bathymetry.
INTRODUCTION A classic lock exchange experiment in a laboratory separates two
different densities by a lock that is removed (_e.g._ ). As the lock is removed,
the lighter water flows over the heavier and the heavier water flows under the
lighter. These two gravity current flows travel quickly, on the order of the
internal wave speed, quickly redistributing the density. Performing the
experiment on a rotating table reduces the lateral width of the gravity currents
but does not significantly change their speed . On the other hand, introducing
turbulence, say in the form of a bubble region, breaks up the gravity currents
and significantly increases the time for density exchange . These basic
dynamics, a contrast in densities driving exchange, and turbulence reducing the
rate of exchange, are expected to explain real oceanographic situations. Here we
look at their application to an estuarine system with a highly constricted, very
turbulent tidal mixing “hotspot”. Using the results from a well-resolved
three-dimensional ocean model, we ask if the laboratory dynamics apply and what
they tell us about the exchange flow for this estuary. In the oceanographic
literature, the estuarine exchange problem has a long, and mostly separate
history from these laboratory studies. In a real estuary, the problem is greatly
complicated by the presence of tides. We cannot remove them (even from our
model) as they are determining the mixing in the system. However, at any given
time, the instantaneous velocity is largely determined by the tides, advecting
water in and out. A traditional way to determine the net estuarine transport
from observations is to assume two layers and to use Knudsen’s Relations, that
is, conservation of water and salt. However, adding symmetrical mixing, as
opposed to just entrainment into the upper layer, makes the system
under-determined. One can use temperature and heating versus salinity to remove
this ambiguity and then invert temperature and salinity profiles to determine
the transport assuming a layer structure . The water advected in and the water
advected out by the tides may be largely the same, and what we want to extract
is the difference. From model results, one can analyze time averages, giving the
tidally averaged velocities and tidally averaged salinity. However, this process
neglects the strong correlations in the fluctuations. A more complete way to do
this is to bin the water and salt fluxes by salinity bin and calculate TEF or
total exchange flow . This method captures both the estuarine exchange flow and
the transport due to the tides, and thus is a total or maximal exchange . The
estuary we will consider is the large, semi-enclosed Strait of Georgia (SoG),
which is connected to the Pacific Ocean through a western and a northern
entrance (Figure [fig:map]). The primary flow is through the western entrance;
the northern entrance is small and flux and exchange there are significantly
smaller than at the west. The major source of fresh water is the Fraser River,
about 60% of the total to the SoG which enters the SoG near its south end. At
the south end of the SoG are the Gulf/San Juan Islands that form lateral
constrictions. The water through this region is also shallower
(Figure [fig:transects]). Thus, tidal flows are high, up to 4.5 m s−1, and
turbulent mixing is strong (Figure [fig:transects]). Water exiting the SoG flows
through this region and then into the relatively straight Juan de Fuca Strait
(Figure [fig:map]), although there is a significant sill, Victoria Sill, at the
eastern end of Juan de Fuca Strait (Figure [fig:transects]). Exchange through
this region has been studied through observations and models . Exchange is
seasonally variable with pulses of freshwater exiting Juan de Fuca Strait during
the Fraser River Freshet, weak neap tides, and winds to the south in SoG . Deep
water renewals similarly occur during neap tides during spring through fall .
The observed dense water cascading from Boundary Pass Sill into the deep SoG has
been successfully explained as a gravity current . Net fluxes have been
estimated at 46 mSv out from Boundary Pass or 114 mSv in from Victoria Sill .
These estimates are based on mass, salt and heat balances and are necessarily
coarse in their vertical resolution and do not include lateral resolution. Using
the TEF method the flux into the SoG is estimated as 83 mSv , updated to 70 mSv
. These two estimates include both the estuarine component and the net tidal
impact. Estimates not including the tidal impact are lower (28 mSv, ). However,
all these estimates include both the flux that transitions the turbulent region
and flux that is recycled within it. In particular, the flux into and out of
Haro Strait is different in because much of the deep flow into Haro Strait is
entrained into the surface flow and exits back out in the surface outflow to
Juan de Fuca Strait. Indeed, although the exchange is maximum during neap tides,
the maximum residual flow actually occurs at spring tides due to this entrained
flux . This short-circuited flow is referred to as the reflux ( _e.g.,_ , ).
Here we will use a Lagrangian tracking method that allows us to separate the
reflux and focus on the flux that travels through the mixing region. This method
does include the effect of the tides. Typically the SoG is divided into three
layers: a surface layer above 50 m, an intermediate layer, and a deep layer
below 200 m (e.g. , ; , ). Looking at the monthly climatology in the central SoG
these depths would correspond to salinities of 30 g kg−1 (range 29.9 g kg−1
(July) to 30.4 g kg−1 (November)), for 50 m and 31.2 g kg−1 (range 31.0 g kg−1
(May) to 31.4 g kg−1 (October)) for 200 m.
Origins of the nitrate 15N depletion in the Mediterranean Sea

Tanja Wald

and 9 more

January 29, 2024
A document by Tanja Wald. Click on the document to view its contents.
Climate adaptation for a natural atoll island in the Maldives - predicting the
long-t...

Floortje Elisabeth Roelvink

and 3 more

January 29, 2024
Coral atoll islands, common in tropical and subtropical oceans, consist of
low-lying accumulations of carbonate sediment produced by fringing coral reef
systems and are of great socio-economic and ecological importance. Previous
studies have predicted that many coral atoll islands will become uninhabitable
before the end of this century due to sea level rise exacerbating wave-driven
flooding. However, the assumption that such islands are morphologically static,
and will therefore ‘drown’ as sea levels rise, has been challenged by
observations and modelling that show the potential for overwashing and sediment
deposition to maintain island freeboard. However, for sustainable habitation,
reliable predictions of island adjustment, flooding frequency and the influence
of adaptation measures are required. Here, we illustrate the effect of various
adaptation measures on the morphological response of an atoll island to future
sea level rise using process-based model simulations. We found that the
assumption of a static island morphology leads to a significant increase in the
predicted frequency of future island flooding compared to morphodynamically
active islands, and demonstrate that natural morphological adjustment is a
viable mechanism to increase island freeboard. Reef adaptation measures were
shown to modify the inshore wave energy, influencing the equilibrium island
crest height and therefore the long-term morphological response of the island,
while beach restoration mainly delays the island’s response. If embraced and
implemented by local communities, allowing for natural island dynamics and
implementing well-designed adaptation measures could potentially extend the
habitability of atoll islands well beyond current projections.
Advancements in Planetary Unstructured Equivalent Source Inversion and Current
Circul...

Boxin Zuo

and 4 more

January 24, 2024
This study presents a novel approach to modeling the Earth’s geomagnetic field,
which originates from electric currents approximately 2,900 km beneath the
surface, crucial for understanding planetary dynamics. We introduce a method for
inverting a planetary-scale equivalent magnetization source and develop a 3-D
equivalent electric current circulation model from this source, enhancing
understanding of these deep currents. This research signifies the first use of
unstructured tetrahedral magnetization inversion technology for planet-scale
magnetic data interpretation and equivalent source model construction. Validated
through a synthetic case study, the method is applied to the International
Geomagnetic Reference Field (IGRF) and SWARM satellite datasets, comprising
35,768 magnetic vectors from two orbital altitudes. Employing various mesh
configurations, we construct and compare detailed current source models from
these datasets. The effectiveness of our equivalent current sources is confirmed
by comparison with dynamo research findings, demonstrating significant
advancements in geomagnetic field modeling, particularly in interpretability,
and providing novel insights into Earth’s magnetic phenomena.
An empirical analysis of factors influencing underrepresented geoscientists'
decisio...

Margaret L Duffy

and 8 more

January 24, 2024
There is a lack of diversity amongst geoscience faculty. Therefore, many
geoscience departments are taking steps to recruit and retain faculty from
underrepresented groups. Here, we interview 19 geoscientists who identify as a
member of an underrepresented race or gender who declined a tenure-track faculty
job offer to investigate the factors influencing their decision. We find a range
of key factors that influenced their decisions to accept or decline a position,
including fit and resources, experiences during job interviews, negotiations and
offers, family, geographic preferences, attention to DEI, personal identities,
mentorship, hiring process, and teaching responsibilities. Despite existing
recommendations for interventions to improve faculty diversity, many of the
participants experienced hiring processes that did not follow these suggested
best practices, suggesting that departments are not all aware of best hiring
practices. Therefore, we leverage our results to provide actionable
recommendations for improving the equity and effectiveness of faculty
recruitment efforts. We find that institutions may doubly benefit from improving
their culture: in addition to benefiting current members of the institution, it
may also help with recruitment.
DiffESM: Conditional Emulation of Temperature and Precipitation in Earth System
Model...

Seth Bassetti

and 3 more

January 24, 2024
Earth System Models (ESMs) are essential tools for understanding the interaction
of the human and Earth systems. One key application of these models is studying
extreme weather events, such as heat waves or high intensity precipitation
events, which have significant socioeconomic consequences. However, the
computational demands of running a sufficient number of simulations to robustly
characterize expected changes in these hazards, and therefore provide a strong
basis to analyze the ensuing risks, are often prohibitive. In this paper we
demonstrate that diffusion models – a class of generative deep learning models –
can effectively emulate the spatio-temporal trends of ESM daily output. Trained
on a handful of runs, reflecting a wide range of radiative forcings, our DiffESM
model takes monthly mean precipitation or temperature as input and is capable of
producing daily values of temperature and precipitation that have statistical
characteristics close to the ESM output. This approach requires only a small
fraction of the computational resources that would be needed to run a large
ensemble under any scenario of interest. We evaluate model behavior over a range
of scenarios, time horizons and two ESMs, using a number of extreme metrics,
including ones that have been long established in the climate modeling and
analysis community. Our results show that the samples produced by DiffESM
closely matches the spatio-temporal behavior of the ESM output it emulates in
terms of the frequency and spatial characteristics of phenomena such as heat
waves, dry spells, or rainfall intensity.
Ionosphere characterization using GPS P3 method by measuring ionospheric delay
in Sou...

Fábio Kei Yamada

and 2 more

January 24, 2024
Ionospheric refraction introduces significant delay and fading in the
electromagnetic signals. This makes the ionosphere the most harmful layer of the
Earth’s atmosphere to the electromagnetic signals emitted by satellites,
impacting the reliability of GNSS services. Depending on the ionization level of
the ionosphere plasma and the signal frequency, these errors can vary from a few
meters to signal unavailability. The main factors influencing ionosphere
plasma’s ionization level are the intensity of solar radiation and the Earth’s
magnetic field. The main parameter to evaluate the behavior of the ionosphere is
the Total Electron Content (TEC), existing between the satellite and the
terrestrial receiver antenna. By predicting the TEC value, it is possible to
predict the effects of ionospheric refraction and develop techniques to increase
reliability in services that depend on GNSS. This study spans the four seasons
from 2018 to 2023, utilizing measurements of ionospheric delays collected by the
UTC(INXE). Daily, seasonal, and annual variations in Vertical TEC (VTEC) values
are analyzed. A comparative assessment is made between the VTEC values obtained
by the GPS P3 method and the Ionospheric Map method for each season until winter
2023. The Analysis of Variance demonstrated the compatibility and comparability
of the two methods. Additionally, this investigation explores changes in the
ionosphere behavior at the UTC(INXE) location during the geomagnetic storms
caused by the solar explosions on April 21, 2023. The findings provide valuable
insights for the ionosphere dynamics and can contribute to developing techniques
to improve GNSS services’ reliability.
Implementation and evaluation of SNICAR snow albedo scheme in Noah-MP (version
5.0) l...

Tzu-Shun Lin

and 6 more

January 24, 2024
The widely-used Noah-MP land surface model (LSM) currently adopts snow albedo
parameterizations that are semi-physical in nature with nontrivial
uncertainties. To improve physical representations of snow albedo processes, a
state-of-the-art snowpack radiative transfer model, the latest version of Snow,
Ice, and Aerosol Radiative (SNICAR) model, is integrated into Noah-MP in this
study. The coupled Noah-MP/SNICAR represents snow grain properties (e.g., shape
and size), snow aging, and physics-based snow-aerosol-radiation interaction
processes. We compare Noah-MP simulations employing the SNICAR scheme and the
default semi-physical Biosphere-Atmosphere Transfer Scheme (BATS) against
in-situ snow albedo observations at three Rocky Mountain field stations. The
agreement between simulated and in-situ observed ground snow albedo in the
broadband, visible, and near-infrared spectra is enhanced in Noah-MP/SNICAR
simulations relative to Noah-MP/BATS simulations. The SNICAR scheme improves the
temporal variability of modeled broadband snow albedo, with a nearly twofold
higher correlation with observations (r=0.66) than the default BATS snow albedo
scheme (r=0.37). The underestimated variability in Noah-MP/BATS is a result of
inadequate physical linkage between snow albedo and environmental/snowpack
conditions, which is substantially improved by the SNICAR scheme. Importantly,
the Noah-MP/SNICAR model, with constraints of snow grain size from the MODIS
snow covered area and grain size (MODSCAG) satellite data, physically represents
and quantifies the snow albedo and absorption of shortwave radiation in response
to snow grain size, non-spherical snow shapes, and light-absorbing particles
(LAPs). The coupling framework of the Noah-MP/SNICAR model provides a means to
reduce the bias in simulating snow albedo.
A novel surface-based approach to represent aquifer heterogeneity in sedimentary
form...

Ludovic Schorpp

and 2 more

January 24, 2024
Sedimentary formations that compose most aquifers are difficult to model as a
result of the nature of their deposition. Their formation generally involves
multiple processes (alluvial, glacial, lacustrine, etc.) that contribute to the
complex organization of these deposits. Representative models can be obtained
using process-based or rule-based methods. However, such methods have several
drawbacks: complicated parametrization, large computing time, and challenging,
if not impossible, conditioning. To address these problems, we propose a new
hierarchical surface-based algorithm, named EROSim. First, a predefined number
of stochastic surfaces are simulated in a given order (from older to younger).
These surfaces are simulated independently but interact with each other through
erosion rules. Each surface is either an erosive or a deposition surface. The
deposition surfaces represent the boundaries of depositional events, whereas the
erosive surfaces can remove parts of the previously simulated deposits. Finally,
these surfaces delimit sedimentary regions that are filled with facies. The
approach is quite simple, general, flexible, and can be conditioned to borehole
data. The applicability of the method is illustrated using data from
fluvio-glacial sedimentary deposits observed in the Bümberg quarry in
Switzerland.
Radiative Heating of High-Level Clouds and its Impacts on Climate

Kerstin Haslehner

and 2 more

January 24, 2024
The interactions of clouds with radiation influence climate. Many of these
impacts appear to be related to the radiative heating and cooling from
high-level clouds in the upper troposphere, but few studies have explicitly
tested this. Here, we use simulations with the ICON-ESM global atmosphere model
to understand how high-level clouds through their radiative heating and cooling
of the atmosphere, influence the large-scale atmospheric circulation and
precipitation in the present-day climate. We introduce a new method to diagnose
the radiative heating of high-level clouds: we use a temperature threshold of
-35°C to define high-level clouds and also include the lower parts of these
clouds at warmer temperatures. The inclusion of the lower cloud parts
circumvents the creation of artificial cloud boundaries and strong artificial
radiative heating at the temperature threshold. To isolate the impact of
high-level clouds, we analyze simulations with active cloud-radiative heating,
with the radiative heating from high-level clouds set to zero, and with the
radiative heating from all clouds set to zero. We show that the radiative
interactions of high-level clouds warm the troposphere and strengthen the
eddy-driven jet streams, but have no impact on the strength of the Hadley
circulation and the latitude of the Intertropical Convergence Zone. Consistent
with their positive radiative heating and energetic arguments, high-level clouds
reduce precipitation throughout the tropics and lower midlatitudes. Overall, our
results confirm that the radiative interactions of high-level clouds have
important impacts on climate and highlight the need for better representing
their radiative interactions in models.
The Interaction Between Climate Forcing and Feedbacks

Andrew Gettelman

and 5 more

January 24, 2024
A Perturbed Parameter Ensemble (PPE) with the Community Atmosphere Model version
6 (CAM6) is used to better understand the sensitivity of simulated clouds to
both aerosol forcing and cloud feedbacks and the interactions between them.
Aerosol forcing through aerosol-cloud interactions is mostly negative (a
cooling) due to shortwave radiation, while feedbacks are positive or negative in
different regions due to contrasting longwave and shortwave effects. Both
forcing and feedbacks are related to the mean climate state. Higher magnitude
cloud radiative effects generally mean larger net forcing and larger net
feedback. Aerosol forcing is broadly related to the susceptibility of clouds to
drop number. Feedbacks are less related to susceptibility, and in different
regions. Aerosol forcing and cloud feedbacks are anti-correlated in the CAM6 PPE
such that stronger negative forcing is associated with stronger positive
feedbacks. Even the processes governing forcing and feedback sensitivity in the
PPE are similar. These include the warm rain formation process, ice loss
processes and deep convective intensity.
Poster_Final_Kadir

Md Nurul Kadir

January 24, 2024
Estuaries are dynamic coastal features that support industry, food production,
and recreation, and provide habitat for numerous animal species. Their typically
low surface gradients make estuaries vulnerable to sea level rise, storms, and
high river water discharge. This vulnerability combined with the large number of
people who often live near estuaries has led to increasing efforts over recent
decades to improve our understanding of how to minimize flooding and protect
people and property. Despite these efforts, however, we still lack the tools to
quantify the relationship between changes in estuarine morphology and flood
risks. In particular, the interplay between bathymetric changes and water levels
during storm conditions remains poorly quantified. To address this knowledge
gap, we present a general enthalpy framework for modeling the evolution of
estuaries that couples a low gradient subaerial topset and a subaqueous offshore
region or foreset. Sediment transport in both the subaerial and subaqueous
domains includes a non-linear term that relates sediment flux, local slope, and
a threshold of motion. With this approach, we describe the evolution of the
bathymetric profile and sediment partitioning between topset and foreset under a
range of sea-level variations scenarios. We find that in some cases upstream
sections of the topset can undergo erosion during periods of sea-level rise and
deposition during sea-level fall, contradicting traditional stratigraphic
models. These counterintuitive bathymetric changes could potentially lead to
shifts in the location of maximum water levels along the estuary not accounted
for by models of storm inundation.
Diurnal tidal influence over self-potential measurements: A Noise or signal for
coast...

PRARABDH TIWARI

January 24, 2024
A document by PRARABDH TIWARI. Click on the document to view its contents.
Towards Semi-Autonomous Robotic Arm Manipulation: Operator Intention Detection
from F...

Abdullah Alharthi

and 3 more

January 24, 2024
In harsh environments such as those found in nuclear facilities, the use of
robotic systems is crucial for performing tasks that would otherwise require
human intervention. This is done to minimize the risk of human exposure to
dangerous levels of radiation, which can have severe consequences for health and
even be fatal. However, the telemanipulation systems employed in these
environments are becoming increasingly intricate, relying heavily on
sophisticated control methods and local master devices. Consequently, the
cognitive burden on operators during labour-intensive tasks is growing. To
tackle this challenge, operator intention detection based on task learning can
greatly enhance the performance of robotic tasks while reducing the reliance on
human effort in teleoperation, particularly in a glovebox environment. By
accurately predicting the operator's intentions, the robot can carry out tasks
more efficiently and effectively, with minimal input from the operator. In this
regard, we propose the utilization of Convolutional Neural Networks, a machine
learning approach, to learn and forecast the operator's intentions using raw
force feedback spatiotemporal data. Through our experimental study on glovebox
tasks for nuclear applications, such as radiation survey and object grasping, we
have achieved promising outcomes. Our approach holds the potential to enhance
the safety and efficiency of robotic systems in harsh environments, thus
diminishing the risk of human exposure to radiation while simultaneously
improving the precision and speed of robotic operations.
Hydrothermal Degassing Through the Karakoram Fault, Western Tibet: Insights Into
Acti...

Maoliang Zhang

and 8 more

January 24, 2024
The Karakoram fault is an important strike-slip boundary for accommodating
deformation following the India-Asia collision. However, whether the deformation
is confined to the crust or whether it extends into the mantle remains highly
debated. Here, we show that the Karakoram fault is overwhelmingly dominated by
crustal degassing related to a 4 He-and CO 2rich fluid reservoir [e.g., He
contents up to ~1.0−1.6 vol.%; 3 He/ 4 He = 0.029 ± 0.016 R A (1σ, n = 50); CO 2
/N 2 up to 3.7−57.8]. Crustal-scale active deformation driven by strike-slip
faulting could mobilize 4 He and CO 2 from the fault zone rocks, which
subsequently accumulate in the hydrothermal system. The Karakoram fault may have
limited fluid connections to the mantle, and if any, the accumulated crustal
fluids would efficiently dilute the uprising mantle fluids. In both cases,
crustal deformation is evidently the first-order response to strike-slip
faulting.
Marine Strontium Isotope Evolution at the Triassic-Jurassic Transition Links
Transien...

Bernát Heszler

and 7 more

January 24, 2024
The end-Triassic extinction (ETE) is one of the most severe biotic crises in the
Phanerozoic. This event was synchronous with volcanism of the Central Atlantic
Magmatic Province (CAMP), the ultimate cause of the extinction and related
environmental perturbations. However, the continental weathering response to
CAMP-induced warming remains poorly constrained. Strontium isotope stratigraphy
is a powerful correlation tool that can also provide insights into the changes
in weathering regime but the scarcity of 87Sr/86Sr data across the
Triassic-Jurassic boundary (TJB) compromised the use of this method. Here we
present new high-resolution 87Sr/86Sr data from bulk carbonates in Csővár, a
continuous marine section that spans 2.5 Myrs across the TJB. We document a
continuing decrease in 87Sr/86Sr the from the late Rhaetian to the ETE,
terminated by a 300 kyr interval of no trend and followed by a transient
increase in the early Hettangian that levels off. We suggest that the first in
the series of perturbations is linked to the influx of non-radiogenic Sr from
the weathering of freshly erupted CAMP basalts, leading to a delay in the
radiogenic continental weathering response. The subsequent rise in 87Sr/86Sr
after the TJB is explained by intensified continental crustal weathering from
elevated CO2 levels and reduced mantle-derived Sr flux. Using Sr flux modeling,
we also find support for such multiphase, prolonged continental weathering
scenario. Aggregating the new dataset with published records employing an
astrochronological age model results in a highly resolved Sr isotope reference
curve for an 8.5 Myr interval around the TJB.
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