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The Tethyan Himalayan sequence (THS) is the structurally highest lithotectonic unit of Indian affinity within the Cenozoic Himalayan orogen. In the NW Himalaya of the Himachal Pradesh, India, the Neoproterozoic–Cretaceous THS is thought to have relatively modest deformation despite the unit commonly recording early collision-related shortening. This lack of significant deformation contrasts that of other Himachal lithotectonic units closer to the foreland. In addition, burial depths of the Himachal THS estimated from structural reconstructions (~10 km) and basal metamorphic pressures (7–8 kbar, ~28 km lithostatic burial) conflict. To address these issues, we performed geologic mapping, thermochronology, and restored new balanced cross sections along two transects across the Himachal THS to better constrain its deformation state and timing, stratigraphic thickness, and burial extent. Along the Spiti and Pin valleys, the THS is shortened by seven NE-dipping thrusts and one SW-dipping thrusts that mostly form fault-propagation folds. The Mata Nappe region (NE of Spiti Valley) has been reinterpreted as a thrust pop-up structure, consistent with structural observations. Along this transect, the estimated THS thickness measured from the basal Akpa granite and Haimanta Group to the uppermost-exposed Tandi Group is ~12.3 km. Restoration of one cross section along this transect yields a minimum shortening of ~30 km (~22% strain). Farther SE along Sutlej Valley, the THS is cut by three SW-dipping thrusts and several S-dipping normal faults. The estimated thickness of the exposed Akpa granite and Haimanta Group is ~8.5 km. Restoration of one cross section along this transect yields a minimum shortening of ~8 km (~21% strain). Thrusts mapped along both transects are interpreted to branch from a single decollement formed by the South Tibet detachment and Great Counter thrust. Our THS shortening estimates added to those for other Indian rocks in the Himachal Himalaya (Webb, 2013) yields a total minimum estimate of ~515–537 km. Preliminary zircon (U-Th)/He dates along Spiti and Pin valleys generally young towards the SW from ca. 42–5 Ma. These results confirm: (1) relatively minor shortening of the Himachal THS that was likely compensated by duplexing of other units; and (2) the discrepancy between THS burial estimates, which may be a product of non-lithostatic pressure. 

Theory suggests the possibility for significant deviations between the total pressure (or dynamic pressure) and lithostatic pressure throughout Earth’s crust. Whether such non-lithostatic pressure conditions are recorded and preserved in the rock record remains unresolved, as direct field confirmation is limited, yet the implications for orogenic reconstruction are profound. Here we investigate the Paleogene Tethyan Himalaya fold-thrust belt in Himachal Pradesh, NW India, which is the structurally highest part of the Himalayan orogen and deforms a ~10–15 km thick Neoproterozoic–Cretaceous passive margin stratigraphic section. Field-based kinematic studies demonstrate relatively moderate shortening strain estimates across the Tethyan Himalaya, yet basal Tethyan strata consistently yield elevated pressure-temperature-time (P-T-t) estimates of 7–8 kbar and ~650°C, indicative of deep burial during Himalayan orogeny (25–30 km depths). These P-T-t conditions can be reconciled by: (1) deep Cenozoic burial along cryptic structures and/or significant flattening of the Tethyan strata; (2) basal Tethyan strata recording pre-Himalayan deformation related to Pan-African orogeny; or (3) non-lithostatic pressure conditions (i.e., tectonic overpressure). To test these models, we systematically mapped the Tethyan fold-thrust belt along the Bhaba Pass-Pin Valley transect in NW India, a classic site for stratigraphic, paleontological, paleoenvironmental, and structural reconstructions. We integrate a multi-method approach combining detailed geologic mapping with quantitative analytical techniques (e.g., finite strain analyses, thermometry, thermobarometry, thermochronology, and geochronology) to quantify the magnitude, kinematics, thermal architecture, and timing of regional deformation, metamorphism, and subsequent exhumation of the Tethyan fold-thrust belt. Our preliminary observations refute deep Cenozoic burial of the Tethyan Himalaya, suggesting either the preservation of non-lithostatic pressures in the rock record or relicts of pre-Himalayan metamorphism. Either scenario demonstrates that caution is required in using Himalayan P-T-t estimates to reconstruct the Cenozoic Himalayan orogeny. 

Tectonic models for the development of the Himalaya, Earth's largest active collisional mountain belt, have been developed and tested through pressure, temperature, and time (P-T-t) information collected from exposed metamorphic rocks. Inferred deep burial and subsequent exhumation of these rocks are usually justified by observable structures (e.g., Main Central thrust) and mapping relationships. However, regions where pressure estimates are at odds with field-based reconstructions are reconciled with hypothesized cryptic structures that have since been completely eroded. Such field versus thermobarometric discrepancies significantly impact interpretations on the geometry, magnitude, and distribution of deformation. Here, we conducted detailed field mapping of the Paleogene Tethyan fold-thrust belt in the Himachal Himalaya, NW India, which is the structurally highest part of the Himalayan orogen and deforms a ~10–15 km thick Neoproterozoic–Cretaceous passive margin section. In this region, P-T estimates yield 6–8 kbar and ~650°C, which suggests burial to depths of ~25–30 km. To assess the viability of this deep burial, we constructed a 1:200,000 scale geologic map of the Bhaba Pass-Pin Valley region. Geologic mapping was focused on the stratigraphy, structural configuration, and metamorphic isograds of the basal Tethyan strata. Detailed field mapping aided the construction of balanced cross sections, which guided subsequent multi-method analytical approaches that fit into a coherent structural framework. Our field observations and map relationships show no major structures, abrupt changes in metamorphic grade or composition that would suggest deep burial of the stratigraphically continuous basal Tethyan group. Balanced cross sections throughout the study area suggest moderate amounts of shortening strain (~30–36%). This contribution highlights the importance of detailed field mapping to interpret P-T estimates. Ongoing analytical methods are being conducted to constrain the thermal architecture and metamorphic history of the Tethyan fold-thrust belt. 

A Novel Community Engaged System Thinking Approach to Controlling Nutrient Pollution in the Belize Cayes Nutrient pollution (anthropogenic discharge of nitrogen and phosphate) is a major concern in many parts of the world. Excess nutrient discharge into nutrient limited waters can cause toxic algal blooms that lead to hypoxic zones, fish die-offs, and overgrowth on reefs. This can lead to coral reefs being more vulnerable to global warming and ocean acidification. For coastal communities that depend of fishing and tourism for their livelihood, and for reefs to protect coastlines, these effects can be devastating. A major source of nutrient input into the aquatic environment is poorly treated wastewater from Onsite Wastewater Treatment Systems (OWTS). When properly sited, built, and maintained conventional OWTS are great for removing fats, grease, biological oxygen demand (BOD), and total suspended solids (TSS), but they are rarely designed for nutrient removal and commonly have high nutrient levels in their effluent. This study investigates the factors that influence the performance of OWTS, the Caribbean region’s most common type of treatment technology, in the Belizean Cayes where salt water flushing is common. Using mass-balance-based models for existing and proposed OWTS to predict the system’s performance under various conditions, along with OWTS’ owner, maintainer, and user input, a novel community engaged system thinking approach to controlling nutrient pollution will be developed. Key model performance metrics are concentrations of nitrogen species, BOD, and TSS in the effluent. To demonstrate the model’s utility, a sensitivity analysis was performed for case studies in Belize, estimating the impact on nutrient removal efficiency when changes are made to variables such as number of daily users, idle periods, tank number and volume, oxygen concentration and recirculation. For the systems considered here, strategies such as aeration, increased biodigester tank size, addition of aerobic and anoxic biodigesters, recirculation, addition of a carbon source, ion exchange media is predicted to decrease the effluent nitrogen concentration, and integration of vegetation for nutrient uptake both on land and in the nearshore environment. In a previous case, the addition of an aerator was predicted to decrease the effluent ammonium concentration by 13%, whereas increasing the biodigester tank size would only decrease the effluent ammonium concentration by ~7%. Model results are shared with system manufacturers and operators to prioritize possible modifications, thereby optimizing the use of finite resources, namely time and money, for costly trial-and-error improvement efforts. 

Poster on using R Shiny Apps within Open OnDemand presented at the PEARC 19 conference 

Abstract A search for leptoquark pair production decaying into$$te^- \bar{t}e^+$$ $t{e}^{-}\overline{t}{e}^{+}$or$$t\mu ^- \bar{t}\mu ^+$$ $t{\mu }^{-}\overline{t}{\mu }^{+}$in final states with multiple leptons is presented. The search is based on a dataset ofppcollisions at$$\sqrt{s}=13~\text {TeV} $$ $\sqrt{s}=13\text{TeV}$recorded with the ATLAS detector during Run 2 of the Large Hadron Collider, corresponding to an integrated luminosity of 139 fb$$^{-1}$$ $_{}^{-1}$. Four signal regions, with the requirement of at least three light leptons (electron or muon) and at least two jets out of which at least one jet is identified as coming from ab-hadron, are considered based on the number of leptons of a given flavour. The main background processes are estimated using dedicated control regions in a simultaneous fit with the signal regions to data. No excess above the Standard Model background prediction is observed and 95% confidence level limits on the production cross section times branching ratio are derived as a function of the leptoquark mass. Under the assumption of exclusive decays into$$te^{-}$$ $t{e}^{-}$($$t\mu ^{-}$$ $t{\mu }^{-}$), the corresponding lower limit on the scalar mixed-generation leptoquark mass$$m_{\textrm{LQ}_{\textrm{mix}}^{\textrm{d}}}$$ $m_{{\text{LQ}}_{\text{mix}}^{\text{d}}}$is at 1.58 (1.59) TeV and on the vector leptoquark mass$$m_{{\tilde{U}}_1}$$ $m_{{\tilde{U}}_1}$at 1.67 (1.67) TeV in the minimal coupling scenario and at 1.95 (1.95) TeV in the Yang–Mills scenario. 

A search for high-mass resonances decaying into a $\tau$-lepton and a neutrino using proton-proton collisions at a center-of-mass energy of $\sqrt{s}=13\mathrm{TeV}$is presented. The full run 2 data sample corresponding to an integrated luminosity of $139{\mathrm{fb}}^{-1}$recorded by the ATLAS experiment in the years 2015–2018 is analyzed. The $\tau$-lepton is reconstructed in its hadronic decay modes and the total transverse momentum carried out by neutrinos is inferred from the reconstructed missing transverse momentum. The search for new physics is performed on the transverse mass between the $\tau$-lepton and the missing transverse momentum. No excess of events above the Standard Model expectation is observed and upper exclusion limits are set on the $W^{\prime }\to \tau \nu$production cross section. Heavy $W^{\prime }$vector bosons with masses up to 5.0 TeV are excluded at 95% confidence level, assuming that they have the same couplings as the Standard Model $W$boson. For nonuniversal couplings, $W^{\prime }$bosons are excluded for masses less than 3.5–5.0 TeV, depending on the model parameters. In addition, model-independent limits on the visible cross section times branching ratio are determined as a function of the lower threshold on the transverse mass of the $\tau$-lepton and missing transverse momentum. © 2024 CERN, for the ATLAS Collaboration2024CERN 

A<sc>bstract</sc> A search for supersymmetry targeting the direct production of winos and higgsinos is conducted in final states with either two leptons (eorμ) with the same electric charge, or three leptons. The analysis uses 139 fb⁻¹ofppcollision data at$$ \sqrt{s} $$ $\sqrt{s}$= 13 TeV collected with the ATLAS detector during Run 2 of the Large Hadron Collider. No significant excess over the Standard Model expectation is observed. Simplified and complete models with and withoutR-parity conservation are considered. In topologies with intermediate states including eitherWhorWZpairs, wino masses up to 525 GeV and 250 GeV are excluded, respectively, for a bino of vanishing mass. Higgsino masses smaller than 440 GeV are excluded in a naturalR-parity-violating model with bilinear terms. Upper limits on the production cross section of generic events beyond the Standard Model as low as 40 ab are obtained in signal regions optimised for these models and also for anR-parity-violating scenario with baryon-number-violating higgsino decays into top quarks and jets. The analysis significantly improves sensitivity to supersymmetric models and other processes beyond the Standard Model that may contribute to the considered final states. 

Abstract A search for pair-produced vector-like quarks using events with exactly one lepton (eor$$\mu $$ $\mu$), at least four jets including at least oneb-tagged jet, and large missing transverse momentum is presented. Data from proton–proton collisions at a centre-of-mass energy of$$\sqrt{s}=$$ $\sqrt{s}=$13 $$\text {TeV}$$ $\text{TeV}$, recorded by the ATLAS detector at the LHC from 2015 to 2018 and corresponding to an integrated luminosity of 139 fb$$^{-1}$$ ${}^{-1}$, are analysed. Vector-like partnersTandBof the top and bottom quarks are considered, as is a vector-likeXwith charge$$+5/3$$ $+5/3$, assuming their decay into aW,Z, or Higgs boson and a third-generation quark. No significant deviations from the Standard Model expectation are observed. Upper limits on the production cross-section ofTandBquark pairs as a function of their mass are derived for various decay branching ratio scenarios. The strongest lower limits on the masses are 1.59 $$\text {TeV}$$ $\text{TeV}$assuming mass-degenerate vector-like quarks and branching ratios corresponding to the weak-isospin doublet model, and 1.47 $$\text {TeV}$$ $\text{TeV}$(1.46 $$\text {TeV}$$ $\text{TeV}$) for exclusive$$T \rightarrow Zt$$ $T\to Zt$($$B/X \rightarrow Wt$$ $B/X\to Wt$) decays. In addition, lower limits on theTandBquark masses are derived for all possible branching ratios.