Valle De Santiago Research Articles

Radiometric dating (40Ar/39Ar and 14C), compositions, and erupted volumes of volcanoes of the Valle de Santiago area (Michoacán-Guanajuato Volcanic Field, Mexico)

Radiometric dating (40Ar/39Ar and 14C), compositions, and erupted volumes of volcanoes of the Valle de Santiago area (Michoacán-Guanajuato Volcanic Field, Mexico)

Effect of inoculation with mycorrhizal fungi on the production of native corn (Zea mays L.) in Valle de Santiago, Gto

The experiment was established from june-december 2022 in a randomised block design with three replications in experimental plot 1 of the Sustainable and Protected Agriculture Career of the Universidad Tecnológica del Suroeste de Guanajuato (UTSOE), located in the municipality of Valle de Santiago. The objective was to evaluate two varieties of native corn of the race harinoso de ocho (red and white) with inoculation with two commercial products containing mycorrhizal fungi (Rhizovibac® and Tec-myc®), a chemical fertilisation based on INIFAP (2015), of 80-40-00 and a fertilisation with vermicompost at a dose of approximately 100 g/mata. The experimental unit consisted of three furrows of eight metres long and 75 cm apart, where root volume - weight and yield were evaluated. Significant differences were found in Fisher's LSD (p≤0.05) for the variables of root volume and weight in the white maize 128.3 cm3 above the mean 72.1 cm3 with chemical fertilisation; however, the criollo corn was the one that obtained the best yield. It can be identified that there is a high relationship between root volume and root weight. In the case of the treatments of the commercial products used in the white corn with Tecmyc®, the lowest root volume - weight and the lowest yield was obtained with the use of Rhizovibac® in comparison with the red corn.

Response of sorghum commercial hybrids to sugarcane aphid, Melanaphis sacchari (Hemiptera: Aphididae) and threshold-based chemical management in Guanajuato, Mexico

The sugarcane aphid, Melanaphis sacchari (Hemiptera: Aphididae) (SCA) affects grain sorghum, Sorghum bicolor (Poaceae) production. The response of sorghum hybrids to SCA was evaluated during 2017 in Guanajuato, Mexico. Experiments were established under strip-plot designs with two factors (hybrids, threshold-based chemical management -TBCM- treatments) and under irrigated or dryland conditions. Experiments were established on two sowing dates at Celaya and Valle de Santiago (irrigated) using the SCA-tolerant hybrids APACHE, BRS-70, MEZQUITE, SCAP-618, and SCA-susceptible UPM-219. Dryland experiments were established at Celaya, Valle de Santiago, and Pénjamo using MEZQUITE, and SCAP-618 (tolerant), and lines UPM-219, SHORTER, and MAJESTIC-355 (susceptible). The TBCM strategies were a) with TBCM (seed treatment with thiamethoxam; flupyradifurone or sulfoxaflor applied to foliage), and b) without TBCM (control). Significant differences (p < 0.05) between treatments under irrigated and dryland conditions for the number of aphids per leaf and grain yield were found. APACHE, BRS-70, and MEZQUITE had the highest grain yields under both TBCM and no-TBCM. UPM-219 was competitive under TBCM conditions, but without TBCM showed total yield losses. The yield–aphid cumulative density linear regressions were negatively significant (p ≤ 0.05) to sorghum cultivated without TBCM. Irrigation increased 64 % grain yields compared with dryland experiments. TBCM increased grain yield (50 % in irrigated and 100 % in dryland conditions). TBCM increased grain yields and reduced cumulative SCA populations under irrigated or rainfed conditions, mainly for susceptible sorghum. Resistant germplasm and TBCM could control SCA in sorghum cultivated in Guanajuato, mainly at late sowings frequently carried out under dryland conditions.

Ecotoxicology of agrochemicals used in valle de Santiago Guanajuato, Mexico

The application of pesticides in the agricultural sector represents multiple benefits such as pest and disease control, however, their application entails risks to the environment and the health of people, which can be accidental or due to improper handling. Therefore, this work focuses on the qualitative determination of the ecotoxicology of pesticides used by seasonal farmers in the Municipality of Valle de Santiago. Information on the most commonly used pesticides in the study area was collected through surveys of seasonal agricultural producers and the main points of sale for agrochemicals. The registry of commercial products with the Federal Commission for Protection against Sanitary Risks in Mexico was consulted to verify the active ingredient and its registered use. The environmental impact of the active ingredient was estimated based on a qualitative matrix to determine total ecotoxicology. The use of pesticides in the study area registered a total of 19 products, of which six are insecticides, 12 are herbicides, and one fungicide. The qualitative estimation of the total ecotoxicology of the active ingredients contained in the pesticides shows that the highest value is possessed by insecticides and to a lesser extent by herbicides.

Adaptation of blueberry crop (Vaccinium corymbosum) under macro-tunnel in Valle de Santiago, Gto.

In order to evaluate the adaptation of Ventura variety blueberry (Vaccinium corymbosum) cultivation under macro tunnel, an experiment was established at the Southwest Technological University of Guanajuato from January to April 2022. The study was established based on a completely randomized experimental design with five treatments and four repetitions. The treatments to be evaluated were four foliar fertilizers: Citan® (rooting hormones); formula 20-30-10 (N, P, K + Microelements); Bayfolan Forte® (N, P, K + Microelements); Demeter Poto® (K, B, Zn, P), applied weekly and an absolute control. The number of green sprouts developed three months after the first application was evaluated. The statistical analysis showed that there were no significant differences (p = 0.01) between the foliar fertilization treatments; however, an average of 13 to 16 green sprouts was counted, all with good development, vigor and physical appearance; largely due to foliar fertilization as a complement to nutrition via irrigation. The adaptation of the blueberry crop was achieved, as a recently introduced species in Valle de Santiago, under macro tunnel conditions, the microclimate and implemented agronomic management; however, it is necessary to improve some management aspects such as nutrition and above all, provide optimal protected conditions for cultivation.

Impact and analysis of electronic invoicing in the primary sector

Electronic invoicing in Mexico is considered under a tax verification scheme, derived by all sales and purchases made, either in a regular period or irregular period, by an economic authority, considering the egresses and also the income. In turn they can be used by buyers and also by sellers, offering the market a good or a service, expressing as a receipt to the authorities, whether federal, state or municipal, also used in internal and external audits. The electronic invoice is a document that verifies the making of a business transaction of a natural person or moral person to a natural or moral person depending on the assumption, and can be digitally or in printed form. This project is carried out in order to have a document that validates the inputs and outputs of goods, for this it is necessary to develop an Accounting-Administrative process, which processes the information and serves for the business management of the entity Granjero Feliz S de R.L de C.V., this process has an alternative that adapts to the rotation of said company which is the Marketing and transformation of pork cuts. The project is developed with the company information, which it has provided, for an accounting period. In this way, the referrals will be properly controlled. It is also important to mention that it can be easy for the authorities to give indications, under the grounds of laws where it obliges users, to use, develop or apply. Those provisions must also be analysed the situation raised which is addressed to the first sector, in this case it is applied to the primary sector, specifically to the primary sector, farmers. The purpose of this research is both to guide and structure the information of a farmer who, for different reasons, is unaware of federal and government provisions to be able to invoice. For the farmer it is very difficult, to understand and understand the tax provisions that challenge him, from the process of developing for obtaining the electronic signature, to the elaboration, issuance and cancellation of the invoice. This research aims to guide and support primary sector individuals, seeing it as an area of opportunity for their better understanding. Also to support you so that you know the administrative facilities from which you have benefit. Considering some of the objectives of this investigation, it is to manage the reality of the farmer's accounting, in accordance with tax procedures and provisions, giving a general diagnosis to the farmer, to contribute to decision-making in the electronic invoicing process. Considering the degree of knowledge of a farmer, he departed from there to provide support and to be able to apply a billing process, and knew the degree involved in this process, considering the obligations to which he is exposed, as part of this regime, of course that many farmers, do not know that they are obliged to invoice for sales made by the sale is a seed considering also in the mistake for the sale of livestock. In particular, the farmer's theme will be touched, through the billing process, thus giving a specific interpretation and analysis to each of the subject. The farmer's location is in a municipality belonging to Valle de Santiago, Gto. Mexico.

Impact and analysis of electronic invoicing in the primary sector

Electronic invoicing in Mexico is considered under a tax verification scheme, derived by all sales and purchases made, either in a regular period or irregular period, by an economic authority, considering the egresses and also the income. In turn they can be used by buyers and also by sellers, offering the market a good or a service, expressing as a receipt to the authorities, whether federal, state or municipal, also used in internal and external audits. The electronic invoice is a document that verifies the making of a business transaction of a natural person or moral person to a natural or moral person depending on the assumption, and can be digitally or in printed form. This project is carried out in order to have a document that validates the inputs and outputs of goods, for this it is necessary to develop an Accounting-Administrative process, which processes the information and serves for the business management of the entity Granjero Feliz S de R.L de C.V., this process has an alternative that adapts to the rotation of said company which is the Marketing and transformation of pork cuts. The project is developed with the company information, which it has provided, for an accounting period. In this way, the referrals will be properly controlled. It is also important to mention that it can be easy for the authorities to give indications, under the grounds of laws where it obliges users, to use, develop or apply. Those provisions must also be analysed the situation raised which is addressed to the first sector, in this case it is applied to the primary sector, specifically to the primary sector, farmers. The purpose of this research is both to guide and structure the information of a farmer who, for different reasons, is unaware of federal and government provisions to be able to invoice. For the farmer it is very difficult, to understand and understand the tax provisions that challenge him, from the process of developing for obtaining the electronic signature, to the elaboration, issuance and cancellation of the invoice. This research aims to guide and support primary sector individuals, seeing it as an area of opportunity for their better understanding. Also to support you so that you know the administrative facilities from which you have benefit. Considering some of the objectives of this investigation, it is to manage the reality of the farmer's accounting, in accordance with tax procedures and provisions, giving a general diagnosis to the farmer, to contribute to decision-making in the electronic invoicing process. Considering the degree of knowledge of a farmer, he departed from there to provide support and to be able to apply a billing process, and knew the degree involved in this process, considering the obligations to which he is exposed, as part of this regime, of course that many farmers, do not know that they are obliged to invoice for sales made by the sale is a seed considering also in the mistake for the sale of livestock. In particular, the farmer's theme will be touched, through the billing process, thus giving a specific interpretation and analysis to each of the subject. The farmer's location is in a municipality belonging to Valle de Santiago, Gto. Mexico.

Impact and analysis of electronic invoicing in the primary sector

Electronic invoicing in Mexico is considered under a tax verification scheme, derived by all sales and purchases made, either in a regular period or irregular period, by an economic authority, considering the egresses and also the income. In turn they can be used by buyers and also by sellers, offering the market a good or a service, expressing as a receipt to the authorities, whether federal, state or municipal, also used in internal and external audits. The electronic invoice is a document that verifies the making of a business transaction of a natural person or moral person to a natural or moral person depending on the assumption, and can be digitally or in printed form. This project is carried out in order to have a document that validates the inputs and outputs of goods, for this it is necessary to develop an Accounting-Administrative process, which processes the information and serves for the business management of the entity Granjero Feliz S de R.L de C.V., this process has an alternative that adapts to the rotation of said company which is the Marketing and transformation of pork cuts. The project is developed with the company information, which it has provided, for an accounting period. In this way, the referrals will be properly controlled. It is also important to mention that it can be easy for the authorities to give indications, under the grounds of laws where it obliges users, to use, develop or apply. Those provisions must also be analysed the situation raised which is addressed to the first sector, in this case it is applied to the primary sector, specifically to the primary sector, farmers. The purpose of this research is both to guide and structure the information of a farmer who, for different reasons, is unaware of federal and government provisions to be able to invoice. For the farmer it is very difficult, to understand and understand the tax provisions that challenge him, from the process of developing for obtaining the electronic signature, to the elaboration, issuance and cancellation of the invoice. This research aims to guide and support primary sector individuals, seeing it as an area of opportunity for their better understanding. Also to support you so that you know the administrative facilities from which you have benefit. Considering some of the objectives of this investigation, it is to manage the reality of the farmer's accounting, in accordance with tax procedures and provisions, giving a general diagnosis to the farmer, to contribute to decision-making in the electronic invoicing process. Considering the degree of knowledge of a farmer, he departed from there to provide support and to be able to apply a billing process, and knew the degree involved in this process, considering the obligations to which he is exposed, as part of this regime, of course that many farmers, do not know that they are obliged to invoice for sales made by the sale is a seed considering also in the mistake for the sale of livestock. In particular, the farmer's theme will be touched, through the billing process, thus giving a specific interpretation and analysis to each of the subject. The farmer's location is in a municipality belonging to Valle de Santiago, Gto. Mexico.

Numerical analysis of the indoor climate in a Zenith-type greenhouse in the Valle de Santiago region, Guanajuato

The objective of this project was to carry out an analysis of the indoor climate of the greenhouse located in the Valle de Santiago region, Guanajuato. It is a zenith-type greenhouse with two wings with a symmetrical face. An orthogonal mesh was made of 50 nodes (25 nodes for each height) Total Den located in the cultivable area and taking the value at the midpoint of each rectangle considering two heights 0.25m and 1.30m with respect to the ground. Humidity and temperature readings were taken in each of the nodes for three weeks and subsequently a data analysis was made and a comparison with the data collected in the different situations; also the temperature was analyzed with the double sum of Riemann and the rule of the middle point. In conclusion, it was determined that the greenhouse yields heat on warm days, while it receives heat on cold days. This behavior coincides with previous studies; however, it occurs that with the hydroponic method there is a greater growth of the crop.

Total CO2 output and carbon origin discharged from Rincón de Parangueo Maar (México)

A geochemical survey was carried out (May 2016) in the Rincón de Parangueo maar in Valle de Santiago, México. The challenge was to measure CO2 and CH4 fluxes discharged from soil and to investigate the chemical and isotopic compositions of interstitial soil gases and remaining vents at the bottom of maars system subjected to critical and high rate drawdown aquifer. Total CO2 flux calculated by sequential Gaussian simulation is 10.6 ton d−1 (±2.1 ton d−1) over the entire crater maar area. Two degassing groups were recognized: Group A (background degassing) with values lower than 10 g m−2 d−1 (40% of the total measurements) and Group B with values ranging between 10 and 347.1 g m−2 d−1 (60% of the total amount of measurements). CH4 flux ranges from 2.1 to 1577 g m−2 d−1. CH4/CO2 flux mean ratio is ~20.51 while CH4/CO2 concentration ratios are 78 and 119 for bubbling gases and 8.4 for interstitial gases. The δ13C-CH4 values are ~65 per mil vs V-PDB indicating a biogenic origin of methane in bubbling and interstitial gases. The δ13C-CO2 values, ranging from −10.6 to −27.6 and −1.9 per mil vs V-PDB for bubbling gases and the interstitial gases, respectively, suggest secondary CO2 consumption within the soil.

The impact of insecurity and violence on the sales of Micro and Small companies in the city of Valle de Santiago, Guanajuato

Nationwide, 63.0% of companies consider insecurity and crime as a major problem that affects them. (INEGI, 2018). On 2018 in Guanajuato, 93.3% of companies considered it unsafe, with an increase of 38.3% over 2016 (INEGI, 2018). Their municipalities are no exception, in the case of Valle de Santiago, we seek to analyze the relationship between insecurity and violence with respect to annual sales of micro and small enterprises, the research is conducted through a cross-descriptive design, with a quantitative approach, through the questionnaire as an instrument, obtaining a sample of 550 companies. As a result of the research it was obtained that 90.7% of the directors of the micro and small companies express to be worried by the insecurity and violence that occurs in the municipality and therefore an impact is observed in the annual sales according to the calculation of the R square, obtaining 0.765. Given the importance that micro and small enterprises have for the economic development of the municipality, the issue of insecurity and violence must be considered a priority due to its growing incidence, not only at the local level.

Effects of the transition to the RIF of microenterprises in the city of Valle de Santiago, Guanajuato

As a measure to reduce tax evasion and informality, the Fiscal Incorporation Regime (RIF) arises with the 2014 tax reform, which generated a radical change in tax obligations and in the way taxpayers must comply, a situation that mainly affects micro and small enterprises, so this work aims to identify the affectations and benefits derived from the incorporation into the RIF of micro-enterprises in the city of Valle de Santiago, Guanajuato. The research is based on a qualitative study, applying the in-depth semi-structured interview technique to 30 taxpayers who have been taxing in the RIF since January 1, 2014. The main results indicate that the tax reform is not entirely negative, the intention of the government of reducing informality has been met, however, the execution has setbacks, as small business owners do not have sufficient fiscal culture or technological preparation to fulfill their obligations on their own, in addition to the fact that the increase in operating expenses represents a strong load for companies, a situation that places them at a disadvantage with respect to their competitors.

Impacto e Interpretación de estados financieros en MYPIMES en la región

Accounting is such an ancient activity or discipline that some authors consider it to be art, science or discipline, which teaches the rules and procedures for classifying and recording operations carried out by economic authorities, who are constituted as natural persons or moral persons with commercial, industrial, scientific, religious, government, basic information that serves as a livelihood to develop financial and useful information to the economic body in the taking of of their economic decisions in regular and irregular periods. Whereas some of the objectives of presents her research consists in quantifying the financial reality of the company, according to the rules, procedures and fiscal provisions, through the application of various financial reasons, giving a diagnosis generally to the economic entity, to contribute to decision-making on resource optimization. The present project was carried out with the aim of measuring the economic and financial reality in which most of the companies located in the region are located, it is an important derived issue, where many companies only the objective is to invest, but is not reanalyzed , a financial accounting diagnostic to verify profitability and whether it is appropriate to continue investing, or otherwise make a small modification, and find the right investment point in the business. In particular, the company "Cadena de tiendas Cristyfer" will be discussed through the application of financial reasons, thus giving a specific interpretation and analysis to each of these. Located in the community of San Ignacio de Mogotes, municipality of Valle de Santiago, Gto. México.

Efectos de la transición al RIF de microempresas de la ciudad de Valle de Santiago, Guanajuato

As a measure to reduce tax evasion and informality, the Fiscal Incorporation Regime (RIF) arises with the 2014 tax reform, which generated a radical change in tax obligations and in the way taxpayers must comply, a situation that It mainly affects micro and small businesses, so this work aims to identify the affectations and benefits derived from the incorporation into the RIF of micro-enterprises in the city of Valle de Santiago, Guanajuato; It is based on a qualitative study, applying the in-depth semi-structured interview technique to 30 taxpayers who have been taxing in the RIF since January 1, 2014. The main results indicate that the tax reform is not entirely negative, the intention of the government of reducing informality has been met, however, the execution has setbacks, as small business owners do not have a sufficient fiscal culture or technological preparation to fulfill their obligations on their own, in addition to the fact that the increase in operating expenses represents a strong load for companies, a situation that places them at a disadvantage with respect to their competitors.

Transferencia y conservación de la infraestructura hidroagrícola en el Alto Río Lerma, Guanajuato

<div class="page" title="Page 1"><div class="layoutArea"><div class="column"><p><span><strong>Objetivo - </strong></span><span>evaluar el estado de conservación de la infraestructura hidroagrícola, como resultado del proceso de transferencia a los usuarios del D.R. 011.</span></p><p><strong>Método - </strong><span>análisis estadístico de series de tiempo de las variables de inversión en mantenimiento y conservación, cuotas de riego y volúmenes de agua disponible para riego en el D.R. 011.</span></p><p><strong>Resultados - </strong>la inversión en conservación y mantenimiento no presenta una tendencia creciente en el período posterior al proceso de transferencia, no obstante que se incrementaron las cuotas de riego pagadas por los usuarios, lo que ha incidido negativamente en el estado físico de las obras.</p><p><strong>Limitaciones - </strong>no hay información disponible suficiente para realizar el análisis estadístico de cada uno de los módulos estudiados.</p><p><strong>Principales hallazgos - </strong>a más de dos décadas de la transferencia del manejo de las obras a los usuarios del D.R. 011, las estructuras de riego presentan un notable deterioro, particularmente los módulos Valle de Santiago y Cortázar, donde gran parte de los canales de distribución de la red menor, se encuentran sin revestir y en malas condiciones.</p></div></div></div>

Economic spillover for the patron saint festivities and events of the GTO brand

The research is based on the fact that so much economic spill leave the patron celebrations or events of the GTO brand, in the state of Guanajuato and in its different municipalities where these events are held, to which a wide publicity is carried out by different means, evoking to that the society consumes local and handmade products, to mention an example in the municipality of Valle de Santiago, the chubby festival was held last June “8 thousand people gathered at the chubby festival , about 20 thousand chubby were consumed, had an economic spill of about 4.5 MDP in a single day ”, this published on the page gourmetaro.com.

Balance de nutrientes en sistemas de cultivo de maíz y retos para su sustentabilidad

Introduction: Nutrition management in the maize crop in Guanajuato, Mexico, is based on mineral fertilization, with high doses of nitrogen and reduced application of phosphorus and potassium. Objective: To diagnose the management of mineral nutrition and residues from the maize cropping system, and identify opportunities for their efficient use. Methodology: 68 maize farmers from the municipalities of Salvatierra and Valle de Santiago, Guanajuato, were surveyed. Plot soils were sampled, and yield, nutrient concentration and C mineralization were estimated. With the data obtained, graphs of the balance of N, P, K and C were made. Results: Nutrition management and biomass production varied among farmers. Currently, P and K are not limiting factors, unlike N, since the soil only contributes 11 % of the total available nitrogen. Residue management showed that there is an imbalance between soil C mineralization and the incorporation of residues. Study limitations: The analysis focused on only one agricultural cycle. Originality: The focus of the study, including the graphical analysis, is scarcely applied in the region’s maize farming systems. Conclusions: An integral vision is required for the management of organo-mineral nutrition and residues to contribute to their efficient and sustainable use.

Bioarqueología del Bajo Magdalena, norte de Colombia, América del Sur

The Pre-Hispanic human skeletal collection housed at the museo Mapuka (Universidad del Norte) has been studied in order to contribute to the reconstruction of the life conditions in the past in the Bajo Magdalena. This series integrates the human remains excavated by Angulo Valdes between 1950 and 1980 in the sites Malambo, Cienaga de Guajaro, Tubara and Valle de Santiago. Forty-one individualized skeletons and several assemblages of skeletal elements (MNI, minimal number of individuals, 45) were studied. Although the sample does not allow general conclusions about the populations, because of its MNI and its preservation, the anomalies observed allow approaching to their sufferings.

Petrology and geochemistry of the Valle de Santiago lower-crust xenoliths: Young tectonothermal processes beneath the central Trans-Mexican volcanic belt

We present a comprehensive petrologic study of lower-crust mafic and felsic xenoliths hosted by Quaternary alkaline basalts of the Valle de Santiago monogenetic volcanic field. This is the only locality along the entire Trans-Mexican volcanic belt where the abundance and size of xenoliths allow the understanding in great detail of processes associated with interactions of young subduction-related magmatism and the deep continental crust. Mafic xenoliths (two pyroxene ± spinel granulites and metanorthosites), olivine-rich gabbroic xenoliths, and transitional xenoliths compose the bulk of the population, although a few belong to the charnockitic suite (enderbite and faersundite). Thermobarometric calculations (two-pyroxene, ilmenite-magnetite, Ti-in amphibole, amphibole-plagioclase, and phase equilibria in the system NCMAS (Na-Ca-Mg-Si)) result in pressures around 9 kbar and temperatures of 1000–1100 °C for the granulite-facies metamorphism, which would give a very hot lower crust, ∼33 km thick, beneath Valle de Santiago and a mean geothermal gradient of ∼30 °C/km. Igneous zircons (Th/U = 0.03–0.87) extracted from one of the felsic granulites yielded a major peak of latest Cretaceous age (67.1 Ma), interpreted as the crystallization age of the granitic protolith, without inheritance from Precambrian or Paleozoic crust. Minor peaks at 45.1 and 25.5 Ma are interpreted as partial Pb losses from some of the Cretaceous zircons. Trace-element geochemistry, as well as Sr, Nd, and Pb isotopic studies performed on two granulites, is consistent with the juvenile and coeval nature of both the mafic metagabbroic xenoliths and the alkaline basaltic magmas that lifted the xenoliths from the lower crust. Two intermediate stages in the thermal evolution of the sampled xenoliths include the emplacement at different depths of volatile and K-Fe-Ti–rich oxidized melts represented by igneous assemblages with kaersutite, biotite, titanomagnetite, spinel, plagioclase, Fe-rich epidote, clinopyroxene, fayalitic olivine, and glasses that pervasively invaded most granulite xenoliths before being taken to the surface. A preferred plumbing system model is presented depicting a protracted Miocene to Quaternary basaltic intraplate magmatic system that sampled former basaltic batches stationed in the lower crust, together with the Late Cretaceous deep-seated granitoids beneath Valle de Santiago in the backarc of the central Trans-Mexican volcanic belt. Both components were later subjected to granulite-facies conditions in the lower crust, most probably related to the continued heating of the crust by basaltic magmas underplated in the central Trans-Mexican volcanic belt backarc region.

Holocene climate change and human impact, central Mexico: a record based on maar lake pollen and sediment chemistry

This paper presents multiproxy (pollen, magnetic susceptibility, sediment chemistry) records from two maar crater lakes in the Valle de Santiago of Guanajuato, Mexico: Hoya San Nicolás and Hoya Rincon de Parangueo. Sediment cores from the two sites have basal dates of ca 11,600 and 9600 cal yr BP, respectively. The San Nicolás results show that the lake desiccated several times during the Holocene, and this resulted in the selective destruction of the less resistant pollen types. A comparative analysis of data from both sites indicates that during the earliest Holocene (ca 11,600–9000 cal yr BP) there were short term oscillations of wetter and drier climate; during the early Holocene (ca 9000–5700 cal yr BP) it was on average wetter; during the middle Holocene (ca 5700–3800 cal yr BP) drier; and during the middle to late Holocene (ca 3800–2200 cal yr BP) wetter. Increasing human disturbance during the late Holocene of environment obscures the climatic record. Agricultural activities in the area began as early as ca 5700 cal yr BP and intensified around 2400 cal yr BP.