990 resultados para Prehistoric -- New Mexico
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Preliminary detrital zircon age distributions from Mazatzal crustal province quartzite and schist exposed in the Manzano Mountains and Pedernal Hills of central New Mexico are consistent with a mixture of detritus from Mazatzal age (ca. 1650 Ma), Yavapai age (ca. 1720 Ma.), and older sources. A quartzite sample from the Blue Springs Formation in the Manzano Mountains yielding 67 concordant grain analyses shows two dominant age peaks of 1737 Ma and 1791 Ma with a minimum peak age of 1652 Ma. Quartzite and micaceous quartzite samples from near Pedernal Peak give unimodal peak ages of ca. 1695 Ma and 1738 Ma with minimum detrital zircon ages of ca. 1625 Ma and 1680 Ma, respectively. A schist sample from the southern exposures of the Pedernal Hills area gives a unimodal peak age of 1680 Ma with a minimum age of ca. 1635 Ma. Minor amounts of older detritus (>1800 Ma) possibly reflect Trans-Hudson, Wyoming, Mojave Province, and older Archean sources and aid in locating potential source terrains for these detrital zircon. The Blue Springs Formation metarhyolite from near the top of the Proterozoic section in the Manzano Mountains yields 71 concordant grains that show a preliminary U-Pb zircon crystallization age of 1621 ¿ 5 Ma, which provides a minimum age constraint for deposition in the Manzano Mountains. Normalized probability plots from this study are similar to previously reported age distributions in the Burro and San Andres Mountains in southern New Mexico and suggest that Yavapai Province age detritus was deposited and intermingled with Mazatzal Province age detritus across much of the Mazatzal crustal province in New Mexico. This data shows that the tectonic evolution of southwestern Laurentia is associated with multiple orogenic events. Regional metamorphism and deformation in the area must postdate the Mazatzal Orogeny and ca. 1610 Ma ¿ 1620 Ma rhyolite crystallization and is attributed to the Mesoproterozoic ca. 1400 ¿ 1480 Ma Picuris Orogeny.
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Data on the evolution of geomagnetic paleointensity are crucial for understanding the geodynamo and Earth’s thermal history. Although basaltic flows are preferred for paleointensity experiments, quickly cooled mafic dykes have also been used. However, the paleointensity values obtained from the dykes are systematically lower than those from lava flows. This bias may originate from the difference in cooling histories and resultant magnetic mineralogies of extrusive and intrusive rocks. To explore this hypothesis, the magnetic mineralogy of two feeder dyke-lave flow systems, from Thunder Bay (Canada) and La Cienega (New-Mexico), has been studied using magnetic and microscopy methods. Within each system, the flow and dyke show different stages of deuteric oxidation of titanomagnetite, but the oxidation stages also differ between the two systems. It is concluded that the tested hypothesis is viable, but the relationships between the magnetic and mineralogical properties of flows and dykes are complex and need a further investigation.
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Breast cancer incidence and mortality rates for Hispanic women are lower than for non-Hispanic white (NHW) women, but recently rates have increased more rapidly among Hispanic women. Many studies have shown a consistent increased breast cancer risk associated with modest or high alcohol intake, but few included Hispanic women. Alcohol consumption and risk of breast cancer was investigated in a New Mexico statewide population-based case-control study. The New Mexico Tumor Registry ascertained women, newly diagnosed with breast cancer (1992–1994) aged 30–74 years. Controls were identified by random digit dialing and were frequency-matched for ethnicity, age-group, and health planning district. In-person interviews of 712 cases and 844 controls were conducted. Data were collected for breast cancer risk factors, including alcohol intake. Recent alcohol intake data was collected for a four-week period, six months prior to interview. Past alcohol intake included information on alcohol consumption at ages 25, 35, and 50. History of alcohol consumption was reported by 81% of cases and 85% of controls. Of these women, 42% of cases and 48% of controls reported recent alcohol intake. Results for past alcohol intake did not show any trend with breast cancer risk, and were nonsignificant. Multivariate-adjusted odds ratios for recent alcohol intake and breast cancer suggested an increased risk at the highest level for both ethnic groups, but estimates were unstable and statistically nonsignificant. Low level of recent alcohol intake (<148 grams/week) was associated with a reduced risk for NHW women (Odds Ratio (OR) = 0.49 95% Confidence Interval (CI) 0.35–0.69). This pattern was independent of hormone-receptor status. The reduced breast cancer risk for low alcohol intake was present for premenopausal (OR = 0.29, 95% CI 0.15–0.56) and postmenopausal NHW women (OR = 0.56, 95% CI 0.35–0.90). The possibility of an increased risk associated with high alcohol intake could not be adequately addressed, because there were few drinkers with more than light to moderate intake, especially among Hispanic women. An alcohol-estrogen link is hypothesized to be the mechanism responsible for increased breast cancer risk, but has not been consistently substantiated. More studies are needed of the underlying mechanism for an association between alcohol intake and breast cancer. ^
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Although, elevated risk for lung cancer has been associated with certain industries and occupations in previous studies, the lack of cigarette smoking information in many of these investigations resulted in estimates that could not be adjusted for the effects of smoking. To determine lung cancer risk due to occupation and smoking, for New Mexico's Anglos and Hispanics, a population-based case-control study was conducted. Incident cases diagnosed 1980-1982, and controls from the general population, were interviewed for lifetime occupational and smoking histories. Specific high risk industries and occupations were identified in advance and linked with industrial and occupational codes for hypotheses-testings. Significantly elevated risks were found for welders (RR = 3.5) and underground miners (RR = 2.0) with adjustment for smoking. Because shipbuilding was the industry of employment for only five of the 18 cases who were welders, exposures other than asbestos could be causal agents. Among the underground for only five of the 18 cases who were welders, exposures other than asbestos could be causal agents. Among the underground miners, uranium, copper, lead and zinc, coal, and potash mining industries were represented. Low prevalence of employment in some of the industries and occupations of interest resulted in inconclusive results. ^
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"The pr1.mary purpose of this thea1a waa to learn about and t .o produce a aeries of pa1nt1n~.a that aymbolized. tbe oil induatry 1n Lea. Count,-, New ltexic.o. The secondary purpose waa to learn more about tho oil industry, which is the big business in Le.a Countj, :New Mexico"
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Soil erosion is a naturally occurring process that involves the detachment, transport, and deposition of soil particles. Disturbances such as thinning and wildfire can reduce cover greatly and increase erosion rates. Forest managers may use erosion prediction tools, such as the Universal Soil Loss Equation (USLE) and Water Erosion Prediction Project (WEPP) to estimate erosion rates and develop techniques to manage erosion. However, it is important to understand the differences and the applications of each model. Erosion rates were generated by each model and the model most applicable to the study site, Los Alamos, New Mexico was determined. It was also used to find the amount of cover needed to stabilize soil. The USLE is a simpler model and less complicated than a computer model like WEPP, and thus easier to manipulate to estimate cover values. Predicted cover values were compared to field cover values. Cover is necessary to establish effective erosion control guidelines.
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n.s. no.35(2003)
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v.14:no.8(1963)
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Thesis--Univ. of Pennsylvania.
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Issued Feb. 1977.
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Conference guide.
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Mode of access: Internet.