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DOE OSTI2024

Effectiveness of denoising diffusion probabilistic models for fast and high-fidelity whole-event simulation in high-energy heavy-ion experiments

Artificial intelligence (AI) generative models, such as generative adversarial networks (GANs), variational autoencoders, and normalizing flows, have been widely used and studied as efficient alternatives for traditional scientific simulations. However, they have several drawbacks, including training instability and inability to cover the entire data distribution, especially for regions where data are rare. This is particularly challenging for whole-event, full-detector simulations in high-energy heavy-ion experiments, such as sPHENIX at the Relativistic Heavy Ion Collider and Large Hadron Collider experiments, where thousands of particles are produced per event and interact with the detector. This work investigates the effectiveness of denoising diffusion probabilistic models (DDPMs) as an AI-based generative surrogate model for the sPHENIX experiment that includes the heavy-ion event generation and response of the entire calorimeter stack. DDPM performance in sPHENIX simulation data is compared with a popular rival, GANs. Results show that both DDPMs and GANs can reproduce the data distribution where the examples are abundant (low-to-medium calorimeter energies). Nonetheless, DDPMs significantly outperform GANs, especially in high-energy regions where data are rare. Additionally, DDPMs exhibit superior stability compared to GANs. The results are consistent between both central and peripheral centrality heavy-ion collision events. Moreover, DDPMs offer a substantial speedup of approximately a factor of 100 compared to the traditional Geant4 simulation method.

42 ENGINEERING↗

DOE OSTI2013

Preparation of nuclear libraries with deterministic and stochastic methods for LWR reflectors

The explicit reflector methodology is used in the system of codes CASMO-5 / SIMULATE-3 to include the reflector around the active core into the computational region and avoid adopting any ad-hoc or experimental albedo coefficients as boundary conditions. However, to complete the core calculation, a set of cross sections and discontinuity factors is needed for the reflector nodes and the accuracy of these nuclear parameters influences the final results, in particular along the peripheral regions of the core. In this paper the explicit reflector methodology of CASMO-5 is adopted to evaluate the few-group cross sections and discontinuity factors of the different reflector cases, based on the design of Generation II and III LWR reactors. In addition, in the perspective of using Monte-Carlo codes as a complementary option for lattice calculations of reflector configurations, the stochastic SERPENT code is also included as part of this benchmark. With the latter, the impact of applying 2-D reflector models with homogenized materials instead of explicit representation of the real geometrical structures is moreover evaluated and shown to be limited. (authors)

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗

DOE OSTI2016

Nonselective inhibition of the epigenetic transcriptional regulator BET induces marked lymphoid and hematopoietic toxicity in mice

Bromo and extra terminal (BET) proteins (BRD2, BRD3, BRD4 and BRDT) are epigenetic transcriptional regulators required for efficient expression of growth promoting, cell cycle progression and antiapoptotic genes. Through their bromodomain, these proteins bind to acetylated lysine residues of histones and are recruited to transcriptionally active chromatin. Inhibition of the BET-histone interaction provides a tractable therapeutic strategy to treat diseases that may have epigenetic dysregulation. JQ1 is a small molecule that blocks BET interaction with histones. It has been shown to decrease proliferation of patient-derived multiple myeloma in vitro and to decrease tumor burden in vivo in xenograft mouse models. While targeting BET appears to be a viable and efficacious approach, the nonclinical safety profile of BET inhibition remains to be well-defined. We report that mice dosed with JQ1 at efficacious exposures demonstrate dose-dependent decreases in their lymphoid and immune cell compartments. At higher doses, JQ1 was not tolerated and due to induction of significant body weight loss led to early euthanasia. Flow cytometry analysis of lymphoid tissues showed a decrease in both B- and T-lymphocytes with a concomitant decrease in peripheral white blood cells that was confirmed by hematology. Further investigation with the inactive enantiomer of JQ1 showed that these in vivo effects were on-target mediated and not elicited through secondary pharmacology due to chemical structure.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2025

Probing the Mechanism of Selective Phosphate Adsorption from Wastewater Using Aqueous and Synchrotron X-ray Characterization

Ion exchange shows promise for recovering phosphate from wastewater as value-added products, but requires high phosphate selectivity to compete with conventional treatment. Hybrid anion exchange (HAIX) resins, which contain non-selective basic functional groups and selective iron oxide nanoparticles (FeOnp), can effectively remove phosphate from wastewater. However, knowledge gaps remain regarding the mechanisms of phosphate selectivity and influence of competing ions, hindering needed efforts to model adsorption dynamics and design scalable adsorption processes for varying wastewaters. To address these gaps, we integrated aqueous-phase adsorption analysis with solid-phase, synchrotron-based X-ray characterization; this integration facilitated elucidation of the distribution and speciation of iron, phosphate, and competing anions on HAIX resins. We compared a quaternary ammonium-functionalized HAIX resin (SBA) to a tertiary amine version (WBA) to determine the role of functional groups. X-ray radiography revealed differences in FeOnp speciation (goethite vs. ferrihydrite) and distribution (peripheral vs. homogeneous) between the resins, resulting in varied phosphate affinity and intraparticle diffusion resistance. Using micro-X-ray fluorescence (μ-XRF) and micro-X-ray absorption near-edge structure (μ-XANES) spectroscopy, we identified differences in where and how phosphate binds across resin types and wastewaters. Across wastewater compositions, FeOnp sites in WBA contribute more to phosphate adsorption than in SBA, possibly due to variations in Fe distribution and speciation. Phosphate adsorption densities calculated from quantitative μ-XRF maps matched those from aqueous analysis, demonstrating the effectiveness of this integrated approach. Altogether, results demonstrate the use of synchrotron-based X-ray characterization for investigating adsorption mechanisms and advance HAIX as a phosphate recovery technology from complex wastewaters.

Nutrient recovery↗

DOE OSTI2013

Photoinitiated Electron Transfer in Zinc Porphyrin-Perylenediimide Cruciforms and Their Self-Assembled Oligomers

Two X-shaped, cruciform electron donor 2 –acceptor–acceptor' 2 (D 2 -A-A' 2 ) molecules, 1 and 2, in which D = zinc 5-phenyl-10,15,20-tripentylporphyrin (ZnTPnP) or zinc 5,10,15,20-tetraphenylporphyrin (ZnTPP), respectively, A = pyromellitimide (PI), and A' = perylene-3,4:9,10-bis(dicarboximide) (PDI), were prepared to study self-assembly motifs that promote photoinitiated charge separation followed by electron and hole transport through π-stacked donors and acceptors. PDI secondary electron acceptors were chosen because of their propensity to form self-ordered, π-stacked assemblies in solution, while the ZnTPnP and ZnTPP donors were selected to test the effect of peripheral substituent steric interactions on the π-stacking characteristics of the cruciforms. Small- and wide-angle X-ray scattering measurements in toluene solution reveal that 1 assembles into a π-stacked structure having an average of 5 ± 1 molecules, when [1] ≅ 10 –5 M, while 2 remains monomeric. Photoexcitation of the π-stacked structure of 1 results in formation of ZnTPnP •+ -PI-PDI •– in τ CS1 = 0.3 ps, which is nearly 100-fold faster than the formation of ZnTPnP •+ -PI •– in a model system lacking the PDI acceptor. The data are consistent with a self-assembled structure for 1 in which the majority of the intermolecular interactions have the ZnTPnP donor of one monomer cofacially π-stacked with the PDI acceptor of a neighboring monomer in a crisscrossed fashion. In contrast, 2 remains monomeric in toluene, so that photoexcitation of ZnTPP results in the charge separation reaction sequence: 1* ZnTPP-PI-PDI → ZnTPP •+ -PI •– -PDI → ZnTPP •+ -PI-PDI •– , where τ CS1 = 33 ps and τ CS2 = 239 ps. The perpendicular orientation of ZnTPnP and ZnTPP relative to PDI in 1 and 2 is designed to decrease the porphyrin–PDI distance without greatly decreasing the overall number of bonds linking them. This serves to decrease the Coulomb energy penalty required to produce D •+ -PI-PDI •– relative to the corresponding linear D-PI-PDI array, while retaining the weak electronic coupling necessary to achieve long-lived charge separation, as evidenced by τ CR = 24 ns for ZnTPP •+ -PI-PDI •– .

Conron, Sarah M. Mickley↗

DOE OSTI2014

Influence of myelin proteins on the structure and dynamics of a model membrane with emphasis on the low temperature regime

Myelin is an insulating, multi-lamellar membrane structure wrapped around selected nerve axons. Increasing the speed of nerve impulses, it is crucial for the proper functioning of the vertebrate nervous system. Human neurodegenerative diseases, such as multiple sclerosis, are linked to damage to the myelin sheath through demyelination. Myelin exhibits a well defined subset of myelin-specific proteins, whose influence on membrane dynamics, i.e., myelin flexibility and stability, has not yet been explored in detail. In a first paper [W. Knoll, J. Peters, P. Kursula, Y. Gerelli, J. Ollivier, B. Demé, M. Telling, E. Kemner, and F. Natali, Soft Matter 10, 519 (2014)] we were able to spotlight, through neutron scattering experiments, the role of peripheral nervous system myelin proteins on membrane stability at room temperature. In particular, the myelin basic protein and peripheral myelin protein 2 were found to synergistically influence the membrane structure while keeping almost unchanged the membrane mobility. Further insight is provided by this work, in which we particularly address the investigation of the membrane flexibility in the low temperature regime. We evidence a different behavior suggesting that the proton dynamics is reduced by the addition of the myelin basic protein accompanied by negligible membrane structural changes. Moreover, we address the importance of correct sample preparation and characterization for the success of the experiment and for the reliability of the obtained results.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2023

Sex- and age-specific aspects of human peripheral T-cell dynamics

Background: The diversity of the antigenic T cell receptor (TCR) repertoire clonally expressed on T lymphocytes is a key element of the adaptive immune system protective functions. A decline in diversity in the older adults is associated with health deterioration. This diversity is generated by the rearrangement of TRB genes coding for TCR chains during lymphocyte differentiation in the thymus, but is essentially maintained by peripheral T lymphocytes proliferation for most of life. Deep sequencing of rearranged TRB genes from blood cells allows the monitoring of peripheral T cell repertoire dynamics. We analysed two aspects of rearranged TRB diversity, related to T lymphocyte proliferation and to the distribution of the T cell clone size, in a collection of repertoires obtained from 1 to 74 years-old donors. Results: Our results show that peripheral T lymphocytes expansion differs according to the recombination status of their TRB loci. Their proliferation rate changes with age, with different patterns in men and women. T cell clone size becomes more heterogeneous with time, and, in adults, is always more even in women. Importantly, a longitudinal analysis of TRB repertoires obtained at ten years intervals from individual men and women confirms the findings of this cross-sectional study. Conclusions: Peripheral T lymphocyte proliferation partially depends on their thymic developmental history. The rate of proliferation of T cells differing in their TRB rearrangement status is different in men and women before the age of 18 years old, but similar thereafter.

59 BASIC BIOLOGICAL SCIENCES↗

DOE OSTI2026

Imputation of urban environmental sensor data using gated attention bidirectional long short-term memory (GA-BiLSTM): methods, performance, and implications

Urban environmental monitoring networks frequently encounter significant data gaps due to sensor malfunctions, environmental disturbances, and communication failures. Reliable approaches to address these gaps are essential for ensuring the continuity and quality of environmental data streams. In this study, we developed a gated attention bidirectional long short-term memory (GA-BiLSTM) model to impute missing data in a dense urban monitoring network. Using observations from the CROCUS network in Chicago, we evaluated GA-BiLSTM against widely used approaches (XGBoost and K-nearest neighbors) under scenarios of both short-term intermittent gaps and prolonged outages. GA-BiLSTM consistently outperformed comparative methods, particularly during extended outages of up to ten days, demonstrating its ability to capture spatiotemporal dependencies across sensor nodes. Beyond performance metrics, feature importance and spatial network analyses highlighted the unexpected but critical predictive role of peripheral rural nodes, underlining their strategic value for maintaining robust urban monitoring systems. These results emphasize that advanced imputation methods can substantially improve the reliability of environmental monitoring networks and support more resilient data infrastructures for urban sustainability.

Data imputation↗

DOE OSTI2016

Mesoporous Silica Nanoparticle-Supported Lipid Bilayers (Protocells) for Active Targeting and Delivery to Individual Leukemia Cells

Many nanocarrier cancer therapeutics currently under development, as well as those used in the clinical setting, rely upon the enhanced permeability and retention (EPR) effect to passively accumulate in the tumor microenvironment and kill cancer cells. In leukemia, where leukemogenic stem cells and their progeny circulate within the peripheral blood or bone marrow, the EPR effect may not be operative. Thus, for leukemia therapeutics, it is essential to target and bind individual circulating cells. Here in this research, we investigate mesoporous silica nanoparticle (MSN)-supported lipid bilayers (protocells), an emerging class of nanocarriers, and establish the synthesis conditions and lipid bilayer composition needed to achieve highly monodisperse protocells that remain stable in complex media as assessed in vitro by dynamic light scattering and cryo-electron microscopy and ex ovo by direct imaging within a chick chorioallantoic membrane (CAM) model. We show that for vesicle fusion conditions where the lipid surface area exceeds the external surface area of the MSN and the ionic strength exceeds 20 mM, we form monosized protocells (polydispersity index <0.1) on MSN cores with varying size, shape, and pore size, whose conformal zwitterionic supported lipid bilayer confers excellent stability as judged by circulation in the CAM and minimal opsonization in vivo in a mouse model. Having established protocell formulations that are stable colloids, we further modified them with anti-EGFR antibodies as targeting agents and reverified their monodispersity and stability. Then, using intravital imaging in the CAM, we directly observed in real time the progression of selective targeting of individual leukemia cells (using the established REH leukemia cell line transduced with EGFR) and delivery of a model cargo. In conclusion, overall we have established the effectiveness of the protocell platform for individual cell targeting and delivery needed for leukemia and other disseminated disease.

60 APPLIED LIFE SCIENCES↗

NASA NTRS1987

Implications of lithospheric bending and faulting in lunar mare-terra tectonics

A qualitative model of lithospheric flexure and faulting is proposed which accounts for certain rille fault features around mare regions of the moon. It is suggested that the subsidence of lunar mare basins may be due to the existence of their mascons and their volcanic fills as loads that flexed the lithosphere, in addition to the effects of drying up and cooling of internal hot volumes. Differences in the internal attack against the lunar crust from above and below the mean surface are considered. The rille formation is shown to be characterized by peripheral bulging and bending, and it is suggested that asthenosphere-related effects in lunar tectonics may have been very important.

Raitala, Jouko↗

NASA NTRS1996

In Vitro Interleukin-1 and 2 Production and Interleukin 2 Receptor Expression in the Rhesus Monkey

Anti-human monoclonal antibodies were used to detect and quantify interleukins-1 and 2 and interleukin-2 receptor expression in peripheral blood mononuclear cells from a rhesus monkey. Interleukin-1 production could be induced by phorbol esters (PMA) and was potentiated by phytohemagglutinin (PHA). Interleukin-2 secretion could also be induced by the combination of PHA and PMA, but only weakly with PHA alone. Interleukin-2 receptor expression was present in a subpopulation of unstimulated lymphocytes and could be enhanced by PHA or PMA. These data show once again that the rhesus monkey immune system is cross-reactive with the human one and that rhesus macaque could be a good model to study interleukin therapy.

Schmitt, Didier A.↗

DOE OSTI2012

A geranyl acetophenone targeting cysteinyl leukotriene synthesis prevents allergic airway inflammation in ovalbumin-sensitized mice

Asthma is associated with increased pulmonary inflammation and airway hyperresponsiveness. The current use of corticosteroids in the management of asthma has recently raised issues regarding safety and lack of responsiveness in 5–10% of asthmatic individuals. The aim of the present study was to investigate the therapeutic effect of a non-steroidal small molecule that has cysteinyl leukotriene (cysLT) inhibitory activity, upon attenuation of allergic lung inflammation in an acute murine model. Mice were sensitized with ovalbumin (OVA) and treated with several intraperitoneal doses (100, 20, 2 and 0.2 mg/kg) of 2,4,6,-trihydroxy-3-geranylacetophenone (tHGA). Bronchoalveolar lavage was performed, blood and lung samples were obtained and respiratory function was measured. OVA sensitization increased pulmonary inflammation and pulmonary allergic inflammation was significantly reduced at doses of 100, 20 and 2 mg/kg with no effect at the lowest dose of 0.2 mg/kg. The beneficial effects in the lung were associated with reduced eosinophilic infiltration and reduced secretion of Th2 cytokines and cysLTs. Peripheral blood reduction of total IgE was also a prominent feature. Treatment with tHGA significantly attenuated altered airway hyperresponsiveness as measured by the enhanced pause (Penh) response to incremental doses of methacholine. These data demonstrate that tHGA, a synthetic non-steroidal small molecule, can prevent acute allergic inflammation. This proof of concept opens further avenues of research and development of tHGA as an additional option to the current armamentarium of anti-asthma therapeutics. -- Highlights: ► Safer and effective anti-asthmatic drugs are in great demand. ► tHGA is a new 5-LO/cysLT inhibitor that inhibits allergic asthma in mice. ► tHGA is a natural compound that can be synthesized. ► Doses as low as 2 mg/kg alleviate lung pathology in experimental asthma. ► tHGA is a potential drug lead for the treatment of allergic asthma.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2021

Conceptual Design of Temperature-Controlled Fueled-Salt Irradiation Experiment to Support Demonstration of Advanced Nuclear Reactors

The irradiation testing of fuel-bearing molten salts is critical to supporting the development and demonstration of molten salt reactors (MSRs). These experiments can inform several important reactor design and safety parameters, including source term modeling, evolution of thermophysical properties with burn-up, and the degradation of structural materials under reactor relevant conditions. Idaho National Laboratory is designing an instrumented and heated high temperature molten salt-fueled irradiation capsule to study the behavior of the fuel salt during in-pile irradiation. This paper details the neutronics, thermal, and mechanical analysis performed to-date. Parametric studies are performed to assess a range of material, different experiment dimensions, two in-reactor positions, and the fuel enrichment used. Principal recommendations are to opt for a peripheral reactor position to alleviate neutronic constraints, a thin salt annulus to alleviate thermal constraints, and high-temperature alloys that provide additional safety margins.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

DOE OSTI2021

Coherent $\mathrm{J}/\psi $ and ψ photoproduction at midrapidity in ultra-peripheral Pb–Pb collisions at $\sqrt{s_{\mathrm {NN}}}~=~5.02$ TeV

The coherent photoproduction of J/ψ and ψ' mesons was measured in ultra-peripheral Pb–Pb collisions at a center-of-mass energy $\sqrt{s_{\mathrm {NN}}}~=~5.02$ TeV with the ALICE detector. Charmonia are detected in the central rapidity region for events where the hadronic interactions are strongly suppressed. The J/ψ is reconstructed using the dilepton (l + l - ) and proton–antiproton decay channels, while for the ψ' the dilepton and the l + l - π + π - decay channels are studied. The analysis is based on an event sample corresponding to an integrated luminosity of about 233 μb -1 . The results are compared with theoretical models for coherent J/ψ and ψ' photoproduction. The coherent cross section is found to be in a good agreement with models incorporating moderate nuclear gluon shadowing of about 0.64 at a Bjorken-x of around 6×10 -4 , such as the EPS09 parametrization, however none of the models is able to fully describe the rapidity dependence of the coherent J/ψ cross section including ALICE measurements at forward rapidity. The ratio of ψ' to J/ψ coherent photoproduction cross sections was also measured and found to be consistent with the one for photoproduction off protons.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

NASA NTRS2014

HEMODOSE: A Set of Multi-parameter Biodosimetry Tools

After the events of September 11, 2001 and recent events at the Fukushima reactors in Japan, there is an increasing concern of the occurrence of nuclear and radiological terrorism or accidents that may result in large casualty in densely populated areas. To guide medical personnel in their clinical decisions for effective medical management and treatment of the exposed individuals, biological markers are usually applied to examine the radiation induced changes at different biological levels. Among these the peripheral blood cell counts are widely used to assess the extent of radiation induced injury. This is due to the fact that hematopoietic system is the most vulnerable part of the human body to radiation damage. Particularly, the lymphocyte, granulocyte, and platelet cells are the most radiosensitive of the blood elements, and monitoring their changes after exposure is regarded as the most practical and best laboratory test to estimate radiation dose. The HEMODOSE web tools are built upon solid physiological and pathophysiological understanding of mammalian hematopoietic systems, and rigorous coarse-grained biomathematical modeling and validation. Using single or serial granulocyte, lymphocyte, leukocyte, or platelet counts after exposure, these tools can estimate absorbed doses of adult victims very rapidly and accurately. Some patient data in historical accidents are utilized as examples to demonstrate the capabilities of these tools as a rapid point-of-care diagnostic or centralized high-throughput assay system in a large scale radiological disaster scenario. Unlike previous dose prediction algorithms, the HEMODOSE web tools establish robust correlations between the absorbed doses and victim's various types of blood cell counts not only in the early time window (1 or 2 days), but also in very late phase (up to 4 weeks) after exposure

Hu, Shaowen↗

DOE OSTI2026

Data Summarization and Inference at Scale

This is the final report for the DOE ASCR grant SC-0022260, Data Summarization and Inference at Scale, PI: Alex Pothen, Purdue University. The goal of the project was to solve data-intensive and compute-intensive problems in the physical sciences, engineering, information science, data science, etc. by designing and implementing new algorithms that could work with a subset of the data. The four subgoals were: (a) The solution of problems where the data is too large to be stored in the memory of a computer. In this streaming model of computation, the data arrives as a stream of elements to the computer, each element is processed as it arrives, and a decision is made to discard the data or to store it; only a small subset of the data proportional to the size of the output solution is stored, and when all the data has been streamed, a solution to the problem is computed from the stored subset. (b) The use of machine learning methods to compute solutions to data-intensive problems. The use of GPUs is critical to obtain high performance on machine learning tasks, but their memory sizes are smaller relative to that of CPUs. For large-scale problems, the data is sampled many times, and small samples are used with repetition, for robustness, to compute solutions to inference tasks. This sampling reduces the memory required to solve the problem, but attention is needed to avoid slow convergence to the solutions, and reduced accuracy of inference. We propose submodular optimization, Large Language Models, and physics-informed neural networks to enable GPU computations here. (c) Modeling and visualization of high-dimensional data using interpretable features. Clinical proteomic data sets from immunology for the detection of cancer and other diseases are temporal and high-dimensional, and algorithms for visualizing these data sets using clinically interpretable features are lacking. We propose methods that compute distances based on the optimal transportation problem and graph edit distances to address this problem. We also propose the use of optimal transport-based distances, spatial statistics, and network structure to classify image data sets, We apply these algorithms to electron micrographs of the peripheral nervous system in the digestive tract. (d) The design of data-intensive algorithms on emerging architectures, specifically, noisy, intermediate-scale quantum (NISQ) devices. Quantum computers offer the possibility of exploring large solution spaces due to the principle of superposition, but current quantum computers are limited by few qubits, short coherence times due to noise, poor interconections among the qubits, etc. We propose the use of the divide and conquer paradigm to solve large-scale problems, wherein collections of small subproblems are solved on the quantum devices, and the solutions to the subproblems are integrated into a solution for the original problem on a classical computer.

97 MATHEMATICS AND COMPUTING↗

NASA NTRS1992

Alterations in Skeletal Muscle Microcirculation of Head-Down Tilted Rats

In this study we assessed the function of microscopic blood vessels in skeletal muscle (cremaster muscle) for alterations which may contribute to the observed elevation of blood pressure associated with head-down tilted whole body suspension (HDT/WBS), a model of weightlessness. Arteriolar baseline diameters, vasoconstrictor responses to norepinephrine (NE) and vasodilation to nitroprusside (NP) were assessed in control rats, rats suspended for 7 or 14 day HDT/WBS rats, and rats allowed to recover for 1 day after 7 days HDT/WBS. Neither baseline diameters nor ability to dilate were influenced by HDT/WBS. Maximum vasoconstriction to norepinephrine was significantly greater in arterioles of hypertensive 14 day HDT/WBS rats. This first study of the intact microvasculature in skeletal muscle indicates that an elevated contractility of arterioles to norepinephrine in suspended rats, and suggests an elevated peripheral resistance in striated muscle may contribute to the increase in blood pressures among animals subjected to HDT/WBS.

Musacchia, X. J.↗

NASA NTRS1987

Ancient dorsa-related stresses of the Tharsis region on Mars

The early structural history of the Martian Tharsis bulge was studied in terms of a compensation model proposed by Froidevaux and Isacks (1984) proposed for terrestrial plateau uplift. The analysis was based on the regional topographic data on the bulge and the distribution of compressional tectonic features and major volcanoes. The results indicate that the initial phases of the Tharsis formation were dominated by the mantle plume doming, followed by extrusional dome raising; the volcanism became the most important bulge building factor only after thickening of the crust. The formation of the Tharsis bulge and the partial relaxation of this bulge have led to significant horizontal stresses and compression within the peripheral areas. The compressional peripheral zone around the bulge gave rise to dorsa formation while the high bulge crests have been in tensional state.

Raitala, Jouko↗