Northern Portion Research Articles

Aerosol impacts on the East Asian winter monsoon: Insights from TaiESM1 and CMIP6 simulations

AbstractThe East Asian winter monsoon (EAWM) is an important climate pattern in Southeast Asia. This study delved into the aerosol effects on the EAWM by analysing simulations conducted with the Taiwan Earth System Model version 1 (TaiESM1) model, part of the Coupled Model Intercomparison Project Phase 6 (CMIP6). Our assessment, validated against observational and reanalysis data, revealed that TaiESM1 effectively replicates the robust circulation of the EAWM and aerosol concentrations, placing its performance above average level among CMIP6 models. Notably, the simulated global mean aerosol optical thickness exhibited an approximately 20% increase from 1850 to 2014. The increased aerosols corresponded to a weakened Aleutian Low and an intensified Siberian High, leading to a weakened EAWM in the lower atmosphere over extratropical areas. In addition, the cooling across the Northern Hemisphere might affect enhanced northerly winds at approximately 10°N, which are situated in the southern part of the EAWM. An analysis of the near‐surface temperature budget indicated that the aerosol‐induced cooling in East China and India was primarily driven by changes in shortwave and longwave radiation fluxes, albeit slightly offset by sensible heat and latent heat fluxes. Furthermore, our study also reveals that while the mechanisms through which anthropogenic aerosols affect the northern portion of the EAWM vary across most CMIP6 models, their impacts on the tropical region remain consistent.

Genetic Diversity Assessment of Cupressus gigantea W. C. Cheng & L. K. Fu Using Inter-Simple Sequence Repeat Technique

Cupressus gigantea W. C. Cheng & L. K. Fu is an endemic conifer tree species that is distributed widely along the northern portion of the deep gorge of the Yarlung Tsangbo River on the Tibetan Plateau. However, as a key plant species growing on the Tibetan plateau, C. gigantea has since become an endangered species due to habitat loss and degradation, overexploitation, and other factors. It has been listed as a first-grade national protected wild plant species in China. Accordingly, to conserve this plant species, we should obtain more information on its genetic structure. In this study, the genetic diversity and structure among 67 samples were evaluated by the inter-simple sequence repeat (ISSR) technique. Overall, 78 bands were produced with a molecular length of 200 bp to 3100 bp using 10 ISSR primers. The mean values for the average number of alleles (Na), effective number of alleles (Ne), Nei’s gene diversity (H), and Shannon’s information index (I) were 1.529, 1.348, 0.199, and 0.293, respectively. Additionally, the number of polymorphic loci (NPLs) and percentage of polymorphic loci (PPLs) averaged 41.25 and 52.90, respectively. Further, total variation among populations was 14.2%, while that within populations was 85.8%; accordingly, the within-population genetic differentiation was found to be significant (p < 0.001). These results demonstrated that a genetic structure model with K = 3 fitted the data best, which agreed with the unweighted pair group method with arithmetic average (UPGMA) cluster and the principal coordinate analysis (PCoA). These findings are beneficial for ensuring the development and genetic protection of C. gigantea populations in the future.

Callicebus oenanthe (Primates: Pitheciidae)

Abstract Callicebus oenanthe Thomas, 1924, commonly known as the San Martín Titi Monkey, is endemic to the northern portion of the department of San Martin, in the Alto Mayo and Huallaga river valleys. It lives in family groups, consisting of a monogamous pair and their offspring. It occurs at elevations between 200 and 1,000 m. Callicebus oenanthe feeds primarily on fruit, but includes other foods like leaves, flowers, and invertebrates in its diet. Although locally common, the species is listed as “Critically Endangered” (CR) both by the International Union for Conservation of Nature and under Peruvian legislation.

Updated geographic distributions for Texas reptiles

As is the case for many taxa in the Anthropocene, reptile conservation is challenged by an assortment of human-mediated factors. Distributional data for reptile species can be highly useful for informing conservation action. For example, species occurrence data can be used to model suitable habitat as well as quantify contraction, expansion, or shift in the distribution of a species. Texas, USA has a rich reptile fauna including one crocodilian, 32 testudine, 55 lacertilian, and 82 serpent species. However, literature pertaining to the distribution of these species has not been synthesized for over a decade. The goals of our study were to visually summarize all published distributional data for reptile species in the state with updated distribution maps; to tabulate all novel and historic distribution data that is absent from the last statewide synthesis; and to characterize any taxonomic, geographic, or temporal trends of distribution record reporting that have occurred in the state over the last decade. We discovered a total of 659 records that supplement the maps provided in the last statewide synthesis, 40% of which were found in published materials that predate that synthesis. Regarding distributional records published over the last decade, there was no apparent temporal trend – record reporting across years appeared to be stochastic. The number of records published for reptile families generally followed patterns of species richness, although several families had fewer or more records than would be expected. These results might be due to several factors including species biology, variable rates of potential range spread or contraction, and variable research attention (historically and contemporarily). Spatially, we found hot spots of record reporting in the southern, western, and northern portions of the state. We suspect these represent either a contemporary geographic bias of research attention, historically poor range characterization for reptile species occupying these regions, or a combination of both. We also found cold spots of record reporting in the northwestern portion of the Panhandle. These are likely due to natural patterns of reptile diversity as well as geographically biased research attention. Future work to be conducted on reptile distributions in Texas should include a thorough synthesis and revisiting of the voucher specimen data associated with these records.

A changing river: Long‐term changes of sinuosity and land cover in the Navasota River Watershed, Texas

AbstractThe Navasota River Basin, itself a tributary of the Brazos River in Texas, is a dynamic watershed undergoing many natural and anthropogenic changes. Local stakeholder involvement in this watershed is quite high, and many landowners in the southern portion of the watershed have concerns regarding the increasing frequency and duration of flooding on private property adjacent to the river, often attributing these impacts to the construction of the Lake Limestone dam. In this study, we examine historical flow data, channel morphology, land use/land cover, and precipitation. Our findings indicate that while there appears to be increasing flow in the northern portion of the watershed, temporal data gaps near the watershed outfall prevent the indication of such a trend in the southern portion of the watershed. Nevertheless, other natural and anthropogenic factors are evident in the watershed that may have a significant influence on downstream flooding. Overall river sinuosity (meandering) declined over the study period, with some river segments encountering significant straightening. Total river length declined by 4.3 km from 1972 to 2020. The number and length of offtake channels also decreased substantially during this period. Land use/land cover use shifted dramatically, with a 39.2% increase in impervious cover and a 12.5% decrease in herbaceous cover since 1972. Finally, yearly precipitation increased, with the change point occurring in 1972. Our findings suggest that the shortening and straightening of the river has reduced its volumetric capacity over time. Coupled with increasing impervious surface cover and precipitation, more water is being delivered downstream at a rate exceeding the watershed's ability to discharge it, thereby contributing to flooding issues expressed by stakeholders. We recommend that bathymetric data and supplemental flow monitoring and modeling within the watershed is needed to fully understand how anthropogenic and natural forces may further affect streamflow in the future.

Geological and anthropogenic contributions of metal(loid)s in the artisanal and small-scale mining-impacted Ocoña watershed of Arequipa, Peru

Strategies to resolve conflicts around water supply and quality in mining-impacted communities include a better understanding of the role and mitigation of mining activities proximal to surface water bodies. The Ocoña watershed of Arequipa (Peru) is one such region where there are conflicts between artisanal miners, fishers, and agriculture over local water resources. The aim of this study is to develop a workflow that leverages existing water quality monitoring and geological mapping to identify major processes that adversely impact water quality with a focus on the relative contribution of mining-related activities on the Ocoña watershed. This study integrates a statistical evaluation of water chemistry data, concentration-discharge relationships, and detailed mineralogy with geochemical modeling to identify sources and mechanisms of contaminant contributions to surface waters in the Ocoña watershed. This revealed that primary deposit mineralogy and seasonal variations exert direct effects on water quality in this mining-active watershed. Multivariate statistical analysis reveals two distinct hydrogeochemical signatures in Ocoña River water that likely represent natural geothermal activity in the northern portion and acid mine drainage contribution in the southern portion of the watershed. In both cases, anthropogenic activities such as mining and agricultural may increase contaminant mobilization. Interestingly, despite perceived challenges, water quality in the Ocoña watershed is better than that of neighbors potentially due to pH-controlled precipitation of Fe and resultant sorption of metals onto precipitants. However, copper released from acid mine drainage, and in particular peak concentrations during the high flow season, exert a potential for adverse ecotoxicological effects. This workflow could potentially be extrapolated to other regions with similar available data to better identify the relative contributions of natural and anthropogenic pressures to the release of toxic compounds in watersheds of concern.

Mantle Sources and Geochemical Evolution of the Picture Gorge Basalt, Columbia River Basalt Group

The Columbia River Basalt Group (CRBG) is the youngest continental flood basalt province, proposed to be sourced from the deep-seated plume that currently resides underneath Yellowstone National Park. If so, the earliest erupted basalts from this province, such as those in the Picture Gorge Basalt (PGB), aid in understanding and modeling plume impingement and the subsequent evolution of basaltic volcanism. Using geochemical and isotopic data, this study explores potential mantle sources and magma evolution of the PGB. Long known geochemical signatures of the PGB include overall large ion lithophile element (LILE) enrichment and relative depletion of high field strength elements (HFSE) typical of other CRBG main-phase units. Basaltic samples of the PGB have 87Sr/86Sr ratios on the low end of the range displayed by other CRBG lavas and mantle-like δ18O values. The relatively strong enrichment of LILE and depletion of HFSE coupled with depleted isotopic signatures suggest a metasomatized upper mantle as the most likely magmatic source for the PGB. Previous geochemical modeling of the PGB utilized the composition of two high-MgO primitive dikes exposed in the northern portion of the Monument Dike swarm as parental melt. However, fractionation of these dike compositions cannot generate the compositional variability illustrated by basaltic lavas and dikes of the PGB. This study identifies a second potential parental PGB composition best represented by basaltic flows in the extended spatial distribution of the PGB. This composition also better reflects the lowest stratigraphic flows identified in the previously mapped extent of the PGB. Age data reveal that PGB lavas erupted first and throughout eruptions of main-phase CRBG units (Steens, Imnaha, Grande Ronde Basalt). Combining geochemical signals with these age data indicates cyclical patterns in the amounts of contributing mantle components. Eruption of PGB material occurred in two pulses, demonstrated by a ~0.4 Ma temporal gap in reported ages, 16.62 to 16.23 Ma. Coupling ages with observed geochemical signals, including relative elemental abundances of LILE, indicates increased influence of a more primitive, potentially plume-like source with time.

Hurricane Ian Damage Assessment Using Aerial Imagery and LiDAR: A Case Study of Estero Island, Florida

Remote sensing techniques have emerged as an essential tool for conducting damage assessments and are commonly used to improve disaster recovery planning and community resilience policies. The objective of this study was to use aerial imagery data and LiDAR to identify the hardest hit areas, quantify the extent of damages, and compare pre- and post-storm beach morphology conditions in Estero Island, Florida, relating to Hurricane Ian in 2022. This study identified >2400 structures that were impacted by Hurricane Ian, with 170 structures suffering extensive damage. Clustering of heavily damaged buildings was observed on the northern and central portions of the island, with lower levels of damage clustered on the southern part. Among the ‘severely damaged’ and ‘destroyed’ structures were seven mobile home subdivisions. The total assessed value of the heavily damaged structures was estimated at over USD 200 million. The results also indicated substantial post-storm debris and sand deposition across the entire island. Remote sensing provides advanced techniques that can help prioritize emergency response efforts after catastrophic impacts from a natural disaster.

Abstract LB139: Disparities in oral precancerous lesion surveillance in the United States upper Midwest

Abstract Objective: To determine whether geographic representation and race of patients in a regional oral cancer surveillance program (University of Minnesota Cancer Active Surveillance Population (UMN CASP)) mirror characteristics in the corresponding National Cancer Institute (NCI) designated comprehensive cancer center catchment. Introduction: Oral cancer poses a significant public health concern that may be mitigated through lesion surveillance. Representation of patients for clinical trials throughout an NCI cancer center catchment area is a crucial goal to promote improved health outcomes. This study investigates the demographic landscape of patients with preneoplastic oral lesions seen at the CASP. Methods: Through the UMN Clinical and Translational Sciences Institute, we queried 30 International Classification of Disease (ICD) 9 and 10 codes corresponding to 120 unique mucosal oral precancerous lesion descriptors of CASP patients. Automated extraction of electronic medical record (EMR) data for 4,496 patients treated by the senior author between 2011 and 2023 identified 1,375 patients with preneoplastic lesions. The proportion of patients residing in three-digit zip code regions of Minnesota were compared to 2021 American Community Survey state population data. Additionally, race data were compared between CASP patients and the UMN Masonic Cancer Center (MCC) patient catchment data. Results: CASP patients were over-represented relative to state population distributions within the Minneapolis-St. Paul metropolitan area and surrounding suburbs (region 554 p<0.0001 and region 551 p<0.0001). Under-representation of CASP patients was observed in all western and southern border regions (regions 559 p<0.0001, 560 p<0.0001, 561 p<0.0001, 562 p=0.0037, 565 p<0.0001, and 567 p=0.0006) as well as portions of central (563 p<0.0001), northern (566 p=0.0015), and north-eastern (558 p<0.0001) Minnesota. Proportional representation was observed in several regions of central (553 and 564), eastern (550), and north-eastern (557 and 556) Minnesota. Comparisons of CASP race data revealed a higher proportion of black patients (CASP 8.59% [95% CI 7.17-10.27%] vs. MCC 7.16% [95% CI 7.14-7.17%]) and a lower proportion of Asian/Pacific Islander patients (CASP 3.74% [95% CI 2.82-4.94%] vs. MCC 5.32% [95% CI 5.30-5.34%]) relative to MCC catchment patients. White, American Indian/Alaskan Native, and mixed-race groups were proportionally represented in both data sets. Conclusions: These data show that system wide EMR searches can be implemented to identify patients in an NCI cancer center catchment area with precancerous or other at-risk conditions for cancer. Importantly, Native patients were proportionally represented in the screening program while several rural locations were under-represented. This information can instruct the expenditure of additional resources for under-represented groups and permit streamlined enrollment of patients for cancer prevention clinical trials. Citation Format: Alexander J. Dwyer, Lindsey Mortensen, Beverly R. Wuertz, Frank G. Ondrey. Disparities in oral precancerous lesion surveillance in the United States upper Midwest [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr LB139.

Remote Sensing-based Morphometry on the Petroliferous Cambay Rift Basin (Gujarat, Western India)

Abstract The Cambay Rift Basin (CRB) is a product of rifting in western India that formed during India’s drift following the breakup of Gondwanaland during the Early Jurassic and Tertiary Periods. Being petroliferous, the basin has attained paramount attention. Seismicity in CRB proves its present-day tectonic sensitivity. Several NNW-SSE, NW-SE and NE-SW trending faults regulate the channel morphology within a portion of the basin. Drainage network systems are proxies of active faulting. Geomorphic indices e.g., long profile analysis, basin-scale parameters, stream length gradient index and sinuosity index along the main channels in the five watersheds have been evaluated in this work. The Index of Active Tectonics (IAT) is derived from the basin-scale parameters and is clubbed into three classes: class 1 (IAT = 1.4 - 1.9), class 2 (IAT = 1.91 - 2.4) and class 3 (IAT = 2.41 - 2.9). IAT Class 1 indicates a higher present-day tectonic activity than the other watersheds such as 1, 2 and 5. Watersheds in the northern and eastern Cambay region (watersheds 3 and 4, and portions of 1 and 5) exhibit higher tectonic activity. Slope breaks and low sinuosity index near the crossing-points in these northern and eastern portions indicate active / weak zones. Along these zones, channels incise vertically and more efficiently than laterally in watersheds 3 and 4. These weak zones may indicate older structures such as lineaments and faults. The Ahmedabad-Mehsana block in watershed 3 and partly in watershed 1 within the CRB with several oil fields are tectonically highly active. Therefore, well-bore stability studies need to be carried out in this block.

Basin Analysis and Tectonic Evolution of the Upper Campanian- Maastrichtian Succession, Southern Iraq

The tectonic development of the Mesopotamia basin in southern Iraq was studied by calculating subsidence and sedimentation rates for eleven wells distributed over the study area. This was done by calculating backstripping for the Upper Campanian-Maastrichtian sequence. The subsidence rates increased in the south of the region near the Su-4, Su-1, and Lu-2 wells in the Hartha Formation, while the basin of the Shiranish Formation appeared to increase towards the northwest near the Ns-2 well. Then, the subsidence rates in the next formation, Tayarat, increase towards the south, near the wells. Su-1, Su-4, Lu-2. The Hartha Basin was divided into two tectonic parts based on the above. The Shiranish Basin was affected by uplift from the northeast and southeast directions, and due to this, an extremely shallow basin formed with its northern portion exposed during the transgression. At the end of this period, it became the regression stage, where the tectonic uplift began to decrease towards the southwest, and this indicates that the tectonic movement's reactivation due to continental collision, which is evident in the next stage with the deposition of the Alaiji Formation. According to these stratigraphic features, the studied area was divided into two tectonic basins, the northeast basin (Samawa-Nasiriya Subzone) and the southwest basin (Zubair Subzone) separated by tectonic lineament extending from Nasiriya-West Qurna and Zubair oil fields.

Modeling the timing of Patagonian Ice Sheet retreat in the Chilean Lake District from 22–10 ka

Abstract. Studying the retreat of the Patagonian Ice Sheet (PIS) during the last deglaciation represents an important opportunity to understand how ice sheets outside the polar regions have responded to deglacial changes in temperature and large-scale atmospheric circulation. At the northernmost extension of the PIS during the Last Glacial Maximum (LGM), the Chilean Lake District (CLD) was influenced by the southern westerly winds (SWW), which strongly modulated the hydrologic and heat budgets of the region. Despite progress in constraining the nature and timing of deglacial ice retreat across this area, considerable uncertainty in the glacial history still exists due to a lack of geologic constraints on past ice margin change. Where the glacial chronology is lacking, ice sheet models can provide important insight into our understanding of the characteristics and drivers of deglacial ice retreat. Here we apply the Ice Sheet and Sea-level System Model (ISSM) to simulate the LGM and last deglacial ice history of the PIS across the CLD at high spatial resolution (450 m). We present a transient simulation of ice margin change across the last deglaciation using climate inputs from the National Center for Atmospheric Research Community Climate System Model (CCSM3) Trace-21ka experiment. At the LGM, the simulated ice extent across the CLD agrees well with the most comprehensive reconstruction of PIS ice history (PATICE). Coincident with deglacial warming, ice retreat ensues after 19 ka, with large-scale ice retreat occurring across the CLD between 18 and 16.5 ka. By 17 ka, the northern portion of the CLD becomes ice free, and by 15 ka, ice only persists at high elevations as mountain glaciers and small ice caps. Our simulated ice history agrees well with PATICE for early deglacial ice retreat but diverges at and after 15 ka, where the geologic reconstruction suggests the persistence of an ice cap across the southern CLD until 10 ka. However, given the high uncertainty in the geologic reconstruction of the PIS across the CLD during the later deglaciation, this work emphasizes a need for improved geologic constraints on past ice margin change. While deglacial warming drove the ice retreat across this region, sensitivity tests reveal that modest variations in wintertime precipitation (∼10 %) can modulate the pacing of ice retreat by up to 2 ka, which has implications when comparing simulated outputs of ice margin change to geologic reconstructions. While we find that TraCE-21ka simulates large-scale changes in the SWW across the CLD that are consistent with regional paleoclimate reconstructions, the magnitude of the simulated precipitation changes is smaller than what is found in proxy records. From our sensitivity analysis, we can deduce that larger anomalies in precipitation, as found in paleoclimate proxies, may have had a large impact on modulating the magnitude and timing of deglacial ice retreat. This fact highlights an additional need for better constraints on the deglacial change in strength, position, and extent of the SWW as it relates to understanding the drivers of deglacial PIS behavior.

Origin and Geological Implications of Monzogranites and Rhyolitic Porphyries in the Wunugetu Porphyry Copper–Molybdenum Deposit, Northeast China: Evidence from Zircon U-Pb-Hf Isotopes and Whole-Rock Geochemistry

The Wunugetu deposit, a large-scale porphyry copper–molybdenum deposit, is located in the southern Erguna block. Its ore bodies are primarily found within monzogranites, granite porphyries, and biotite monzogranites. Additionally, the deposit contains late-stage intrusive dykes of rhyolitic porphyries. This study examined the deposit’s monzogranites and rhyolitic porphyries using lithogeochemistry, zircon U-Pb dating, and Hf isotopic analysis. The main findings include: (1) Zircon U-Pb dating showed that the monzogranites formed around 209.0 ± 1.0 Ma, whereas the rhyolitic porphyries in the northern portion formed around 170.49 ± 0.81 Ma, suggesting magmatic activity in the deposit spanned from the Late Triassic to the Middle Jurassic. (2) The monzogranites exhibited high silicon content (73.16–80.47 wt.%) and relatively low aluminum content (10.98–14.37 wt.%). They are enriched in alkalis (content: 3.42–10.10 wt.%) and deficient in magnesium and sodium, with aluminum saturation indices (A/CNK) ranging from 1.1 to 2.9. In addition, the monzogranites are enriched in large-ion lithophile elements (LILEs) such as Rb, K, and Ba and deficient in high-field-strength elements (HFSEs) like Nb, P, and Ti. (3) The monzogranites have low Zr + Nb + Ce + Y contents of (151.3–298.6 ppm) × 10−6 and 10,000 × Ga/Al ratios varying between 1.20 and 2.33, suggesting that they are characteristic of I-type granites. (4) Positive zircon εHf(t) values ranging from +0.3 to +7.6 in both rhyolitic porphyry and monzogranite samples, increasing with younger emplacement ages, imply that the deposit’s rocks originated from magmatic mixing between mantle-derived mafic magmas and remelts of the juvenile crust. Considering these results and the regional geological evolution, this study proposes that the Wunugetu deposit was formed in an active continental margin setting and was influenced by the Late Triassic–Middle Jurassic southeastward subduction of the Mongol-Okhotsk Ocean.

Using remote sensing to map degraded mountain peatlands with high climate mitigation potential in Colombia's Central Cordillera

Peatlands are the most carbon-dense ecosystems on earth. In tropical mountains, peatlands are numerous and susceptible to rapid degradation and carbon loss after human disturbances. Quantifying where peatlands are located and how they are affected by land use is key in creating a baseline of carbon stocks and greenhouse gas fluxes from tropical mountain peatlands. However, mapping peatlands in the páramo of the Northern Andes is difficult because they are in a topographically complex environment with nearly continuous cloud cover and frequent conversion to pastures or cropland. The goal of this effort was to identify the different types of páramo peatlands and their degradation patterns in the Colombian Central Cordillera. Moderate resolution cloud-free composites of optical imagery, temporal variance in ALOS- PALSAR L-band SAR, Sentinel-1 C-band SAR, and topography data were used as inputs in a machine learning classifier to identify was used to map 12 land cover classes including peatlands with natural vegetation and peatlands converted to pasture. Field data from 507 control points collected across the study area, including information on the vegetation and carbon content on the top 20 cm of the soil, were used to train and validate the classifier. Results show that the use of multiple platforms and image dates, including variance of the radar returns, is necessary for a clear separation of disturbed and undisturbed peatland classes. Peatland area varied across the study region, covering 7% and 20% of the landscape in the northern and southern portions of the study area, respectively. Disturbed peatlands with exotic grasses cover nearly 2% of the area. The overall accuracy of the peatland classes was 82.6%. Disturbed peatlands with exotic grasses had less carbon in the top 20 cm than undisturbed peatlands with natural vegetation. These results highlight the prevalence of peatlands in the tropical Andes and a promising approach to detecting peatlands converted to agriculture. Understanding the distribution and extent of these carbon dense ecosystems can facilitate the restoration and protection of peatlands in the northern Andes, with implications for the future trajectories of the national greenhouse gas inventory.

Interpretation of Geological Features and Volcanic Activity in the Tsiolkovsky Region of the Moon

The Tsiolkovsky crater is located on the farside of the Moon. It formed in the late Imbrian epoch and was filled with a large area of mare basalts. Multisource remote sensing data are used to interpret the geological features of the Tsiolkovsky area. Compared with previous studies, new remote sensing data and a chronological model based on crater size–frequency distribution are used to further refine the stratigraphic units and determine the absolute ages of the mare basalt units. The evolution of volcanic activity in this crater is discussed. The results are as follows: Abundances of major elements, Th, and silicate minerals suggest that the mare basalt in the crater floor is not a uniform unit but rather nine units with different compositions. The nine basalt units are divided into two episodes of volcanic activity: The first occurred at 3.5–3.7 Ga, when highly evolved lava erupted at the crater floor at a large scale; the second occurred at ~3.4 Ga, when a small area of more primitive lava extended to the northern portion of the crater floor.

The Manantiales Basin, Southern Central Andes (∼32°S), Preserves a Record of Late Eocene–Miocene Episodic Growth of an East‐Vergent Orogenic Wedge

AbstractThe Manantiales basin contains >4 km of nonmarine sedimentary strata that accumulated at 31.75–32.5°S during construction of the High Andes. We report field and analytical data from the underexplored northern portion of this basin. The basin contains upper Eocene–middle Miocene strata that accumulated in back‐bulge or distal foredeep through inner‐wedge‐top depozones of the Andean foreland basin as it migrated through this region. A revised accumulation history for the basin‐filling Río de los Patos and Chinches Formations supports a regional pattern of flexure in front of an east‐vergent orogenic wedge. The former formation consists of eolian and localized fluviolacustrine deposits which accumulated between ca. 38 Ma and ≤34 Ma during thrust belt development in Chile. A subsequent ≤12 Myr hiatus may reflect passage of the flexural forebulge or cessation of subsidence during orogenic quiescence. The overlying Chinches Formation records a transition from the foredeep to wedge‐top depozones. Foredeep deposits of east‐flowing, meandering streams were incised prior to ca. 18 Ma, after which deposits of axial rivers, playas, and perennial lakes ponded in a depression behind orogenic topography to the east. After ca. 15 Ma, alluvial‐fan deposits were syndepositionally deformed adjacent to growing thrust‐belt structures along the western basin margin. Although the basin record supports a westward step in the locus of deformation during Early–Middle Miocene time, it conflicts with models involving west‐vergence of the orogenic wedge. Rather, this pattern can be explained as out‐of‐sequence deformation alternating with wedge forward propagation, consistent with Coulomb wedge models incorporating syntectonic sedimentation.

Metasedimentary rocks of the northern portion of thema Cururé domain, Sergipano belt, Northeastern Brazil: geochemical characterization of their protoliths and tectonic implications

Caracterização dos protólitos de rochas metaclásticas de unidades metamórficas do domínio Macururé, Cinturão Sergipano, com base em elementos maiores e traços, é discutida neste trabalho. Dados geoquímicos para essas rochas metassedimentares indicam predominância de grauvacas nos protólitos que contem também folhelhos e arcóseos subordinados. Elementos maiores, traços e terras raras sugerem fonte para estas rochas com composição da crosta superior média para os protólitos das rochas metassedimentares deste domínio. Mistura de fonte de detritos são indicados para estas rochas resultantes principalmente de detritos de composição intermediária a ácido. Dados de rocha total sugerem arco de ilhas e/ou de margem ativa como cenário geodinâmico mais provável para deposição dos precursores sedimentares das unidades estudadas. Neste contexto, uma configuração back-arc explicaria a natureza mista das áreas fontes inferidas, com detritos do embasamento soerguido e relacionadas ao arco como membros finais das misturas. A geoquímica semelhante das metassedimentares e litologias subjacentes atesta derivação a partir de uma mesma fonte crustal.

Giant Aufeis in the Pangong Tso Basin: Inventory of a Neglected Cryospheric Component in Eastern Ladakh and Western Tibet

Cryosphere studies in High Mountain Asia (HMA) typically focus on glaciers, seasonal snow cover, and permafrost. As an additional and mostly overlooked cryosphere component, aufeis occurs frequently in cold-arid regions and covers extensive areas of the Trans-Himalaya and Tibetan Plateau. This largely neglected cryosphere component generally forms in winter from repeated freezing of seepage or overflow. In this article, the occurrence of aufeis fields in the endorheic Pangong Tso Basin (PTB), with a total area of 31,000 km2, is inventoried and examined. Based on a semi-automatic remote sensing approach using Sentinel-2 imagery, about 1000 aufeis fields were detected in the spring of 2019, covering a total area of approximately 86 km2 and with an average individual size of 0.08 km2, while the largest field covered an area of 14.8 km2. A striking contrast between the northern and southern portions of the PTB characterized the spatial distribution of large aufeis fields. All large (>0.5 km2) and 13 persisting aufeis fields were located along broad valleys in the northern portion. Furthermore, a multi-temporal comparison between 1994 and 2023 shows that the number of remaining aufeis fields in autumn varied between 8 and 29, with a maximum in 2019. Their total area ranged between about 0.3 km2 in 1994 and 2023 to about 1.2 km2 in 2015 and 2019. This study complements recent aufeis inventories from the Trans-Himalayan region of Ladakh and closes the gap to the Tibetan Plateau.

Genetic structuring of Fishers in British Columbia, Canada: implications for population conservation and management

Abstract In the westernmost Canadian province of British Columbia, fishers (Pekania pennanti) occur in low-elevation forested ecosystems in the central and northern portions of the province, with several substantial mountain ranges and rivers bisecting this distribution. The effect of these geographic features on gene flow and population structuring is unknown and may contribute to fishers differentiating into 2 or more populations within the province. To better understand population structuring within the range of fishers in British Columbia, we collected tissue samples from 491 fishers from throughout the province and evaluated variation of neutral genetic markers using a 385-base pair section of the mitochondrial DNA control region and 13 microsatellite loci. Fishers appeared to be genetically structured as hierarchical stepping-stone populations where an upper hierarchical level of genetic partitioning resulted in 2 populations at the provincial scale, with 3 subpopulations occurring in the central interior region. We observed gene flow of 2 to 5 migrants per generation between the 2 upper populations, which was substantially less than the 90 migrants per generation estimated as needed to maintain genetic homogeneity. This resulted in differentiated upper populations (haplotype FST = 0.272, microsatellite FST = 0.049) characterized by relatively low Ne (Columbian population = 252, 95% CI = 185 to 332; Boreal population [British Columbia only] = 136, 95% CI = 92 to 234). The consequence of low gene flow and resultant population structuring is that the Columbian population likely receives relatively little genetic and demographic support from other populations and, combined with precipitous recent declines in its numbers, puts this population at heightened conservation risk. As a result, swift and effective actions are needed to conserve this vulnerable population of fishers.

Climate Change Impacts on Water Temperatures in Urban Lakes: Implications for the Growth of Blue Green Algae in Fairy Lake

Cyanobacteria, also known as blue-green algae, are photosynthetic bacteria that play a crucial role in aquatic ecosystems and are susceptible to changes in temperature. Hence, as global temperatures rise due to climate change, some Cyanobacterial species will thrive in warmer temperatures, which will result in increased blooms during the growing season. The MIKE-3 model is calibrated to existing (2022) conditions and is used to assess the impact of the RCP 4.5 scenario for the year 2050 in Fairy Lake (a shallow urban lake in Ontario). The simulations projected indicate that in 2050, in the central parts of Fairy Lake’s central basin, water temperatures will be above 20 °C for 2281 h compared to 2060 h in 2022. This situation indicates there will be a 10.7% increase in the duration of Cyanobacteria blooms in the central area of Fairy Lake. Similarly, in the northern area of Fairy Lake, the MIKE-3 model results indicate that surface temperature durations above 20 °C will increase from 1628 h to 2275 h for the year 2050, resulting in an additional 647 h of increased temperatures at the surface under RCP 4.5 scenario conditions. This situation indicates there will be a 39.7% increase in the duration of Cyanobacteria blooms in the northern portion of Fairy Lake. These modeling conditions indicate there will be significantly more habitat amenable to Cyanobacteria growth when surface water temperatures are above 20 °C, indicating substantial increases in the available growth time of Cyanobacteria due to climate change, all of which translate to major concerns caused by climate change.