U-Pb ages of detrital zircons in lower Permian sandstone and siltstone of the Permian Basin, west Texas, USA: Evidence of dominant Gondwanan and peri-Gondwanan sediment input to Laurentia

2019 ◽  
Vol 132 (1-2) ◽  
pp. 245-262 ◽  
Author(s):  
Li Liu ◽  
Daniel F. Stockli

Abstract The Permian Basin of west Texas, one of the most economically significant hydrocarbon basins in the United States, formed along the southwest margin of Laurentia in the foreland of the Ouachita-Marathon orogen during the late Paleozoic. While its stratigraphic record temporally coincides with syn- and post-orogenic Ouachita-Marathon sedimentation, sediment provenance, sediment routing and dispersal, and paleo-drainage evolution have remained controversial. This study presents more than 2000 new detrital zircon U-Pb ages from 16 samples across the Permian Basin to elucidate early Permian sediment provenance and basin-fill evolution. The data show that Wolfcampian sandstones are dominated by 950–1070 Ma and 500–700 Ma detrital zircon U-Pb ages, whereas Leonardian sandstones and siltstones are dominated by 500–700 Ma and 280–480 Ma detrital zircon U-Pb ages. Most of these age clusters are not typical Laurentian basement ages, but rather indicative of a southern Gondwanan and peri-Gondwanan sources of Mexico and Central America. This interpretation is corroborated by zircons with peri-Gondwanan and Gondwanan rim-core relationships, as well as major age components of euhedral zircons, matching Maya block basement ages. Regional comparison of these new detrital zircon results with published data from Carboniferous and Permian sedimentary rocks in various terranes of Mexico and Central America, Appalachian foreland basins, Ouachita orogenic belt, midcontinent of United States, and Fort Worth Basin (Texas), indicates that most sediment influx to the Permian Basin during the early Permian (Wolfcampian and Leonardian) was derived from basement or recycled upper Paleozoic strata associated with Gondwanan and peri-Gondwanan terranes in modern Mexico and Central America. North American basements such as the Appalachian Grenville (950–1300 Ma), Granite-Rhyolite (1300–1500 Ma), and Yavapai-Mazatzal (1600–1800 Ma) provinces, appear to have provided only minor amounts of sediment. In light of depositional age constraints, the timing of Marathon-Ouachita collision, and careful detrital zircon U-Pb age spectra comparison, the sediment provenance shift from Wolfcampian to Leonardian points to a diachronous, oblique continent-continent collision between Gondwana/peri-Gondwanan terranes and Laurentia.

2021 ◽  
Vol 5 (1) ◽  
pp. 121-133
Author(s):  
Shyam Sheladia ◽  
P. Hemachandra Reddy

The emergence of age-related chronic diseases within the United States has led to the direct increase of Alzheimer’s disease (AD) as well as other neurological diseases which ultimately contribute to the development of dementia within the general population. To be specific, age-related chronic diseases such as cardiovascular disease, high cholesterol, diabetes, and kidney disease contribute greatly to the advancement and rapid progression of dementia. Furthermore, unmodifiable risk factors such as advancing age and genetics as well as modifiable risk factors such as socioeconomic status, educational attainment, exercise, and diet further contribute to the development of dementia. Current statistics and research show that minority populations such as Hispanic Americans in the United States face the greatest burden of dementia due to the increase in the prevalence of overall population age, predisposing genetics, age-related chronic diseases, low socioeconomic status, as well as poor lifestyle choices and habits. Additionally, Hispanic Americans living within Texas and the rural areas of West Texas face the added challenge of finding appropriate healthcare services. This article will focus upon the research associated with AD as well as the prevalence of AD within the Hispanic American population of Texas and rural West Texas. Furthermore, this article will also discuss the prevalence of age-related chronic diseases, unmodifiable risk factors, and modifiable risk factors which lead to the progression and development of AD within the Hispanic American population of the United States, Texas, and rural West Texas.


2003 ◽  
Vol 17 (6) ◽  
pp. 267-275 ◽  
Author(s):  
Amy Rock Wohl ◽  
Sharon Lu ◽  
Jane Turner ◽  
Andrea Kovacs ◽  
Mallory Witt ◽  
...  

1970 ◽  
Vol 102 (10) ◽  
pp. 1268-1290 ◽  
Author(s):  
Marcos Kogan ◽  
E. F. Legner

AbstractExtensive collections of synanthropic fly parasitoids in animal excrement accumulations in the United States, Mexico, Costa Rica, Puerto Rico, Uruguay, Chile, Denmark, Israel, and South Africa yielded seven forms of a Muscidifurax complex which were totally or partially reproductively isolated. Morphological studies of female and male parasitoids coupled with biological and zoogeographical information permitted the identification of five sibling species. Muscidifurax raptor Girault and Sanders 1910 is redescribed and four additional species are described as new: M. zaraptor, from the southwestern United States; M. raptoroides from Central America and Mexico; M. uniraptor from Puerto Rico, and M. raptorellus from Uruguay and Chile. Biological notes are added to the descriptions, and it was postulated that the genus is undergoing a process of speciation with local populations slowly becoming reproductively isolated and eventually giving rise to morphologically distinguishable entities. Most evidence suggests the establishment of Muscidifurax in the New World, concomitant with or shortly following the establishment of muscoid flies in accumulated excrement. Scanning electronmicroscopy was used in the analysis of some morphological structures.


1983 ◽  
Vol 62 (2) ◽  
pp. 466
Author(s):  
Robert D. Crassweller ◽  
Walter LaFeber

1971 ◽  
Vol 3 (2) ◽  
pp. 151-172 ◽  
Author(s):  
Kenneth J. Grieb

The militarycoup d'étatwhich installed General Maximiliano Hernández Martínez as President of El Salvador during December 1931 created a crisis involving the 1923 Washington Treaties. By the terms of these accords, the Central American nadons had pledged to withhold recognition from governments seizing power through force in any of the isthmian republics. Although not a signatory of the treaty, the United States based its recognition policy on this principle. Through this means the State Department had attempted to impose some stability in Central America, by discouraging revolts. With the co-operation of the isthmian governments, United States diplomats endeavored to bring pressure to bear on the leaders of any uprising, to deny them the fruits of their victory, and thus reduce the constant series ofcoupsandcounter-coupsthat normally characterized Central American politics.


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