Late Cretaceous and Cenozoic History of Laramie Basin Region, Southeast Wyoming

Author(s):  
D. L. Blackstone
Genes ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 517
Author(s):  
Marcel Tongo ◽  
Darren P. Martin ◽  
Jeffrey R. Dorfman

The Congo Basin region is believed to be the site of the cross-species transmission event that yielded HIV-1 group M (HIV-1M). It is thus likely that the virus has been present and evolving in the region since that cross-species transmission. As HIV-1M was only discovered in the early 1980s, our directly observed record of the epidemic is largely limited to the past four decades. Nevertheless, by exploiting the genetic relatedness of contemporary HIV-1M sequences, phylogenetic methods provide a powerful framework for investigating simultaneously the evolutionary and epidemiologic history of the virus. Such an approach has been taken to find that the currently classified HIV-1 M subtypes and Circulating Recombinant Forms (CRFs) do not give a complete view of HIV-1 diversity. In addition, the currently identified major HIV-1M subtypes were likely genetically predisposed to becoming a major component of the present epidemic, even before the events that resulted in the global epidemic. Further efforts have identified statistically significant hot- and cold-spots of HIV-1M subtypes sequence inheritance in genomic regions of recombinant forms. In this review we provide ours and others recent findings on the emergence and spread of HIV-1M variants in the region, which have provided insights into the early evolution of this virus.


2021 ◽  
pp. SP495-2021-72
Author(s):  
Domenico Chiarella ◽  
Daniel Joel

AbstractDeep-marine gravity-driven deposits represent one of the more investigated depositional systems due to their potential interest as target for exploration and carbon capture and storage activities, as well as an important record of the depositional history of a basin through time. Although the Halten Terrace (Norwegian Sea) is one of the main successful exploration areas, we still have poor understanding of the post-rift Cretaceous interval. Here, 3D seismic reflection and borehole data are integrated to investigate the stratigraphic distribution and sedimentological characteristics of the Cenomanian-Turonian intra Lange Sandstones in the Gimsan Basin and Grinda Graben. The Lange Formation records the deposition in a deep-marine environment of a thousand meter thick shale unit punctuated by tens of meters thick gravity-driven coarse-grained sandstone intervals sourced from the Norwegian mainland. The presence of gravity-driven deposits and the deep-marine setting is supported by seismic interpretation, architectural elements and the facies analysis of cored material acquired within the studied stratigraphic interval. Borehole data indicate the presence of both turbidites and hybrid-event beds rich in mud content. The results of this study have implications for the understanding of the distribution and reservoir potentiality of the Late Cretaceous Lange Formation in the Halten Terrace.


Author(s):  
Alan Graham

The arrangement of vegetation over the landscape is a product of interactions between the environment, the ecological characteristics of individual organisms, barriers, dispersal potential, epidemic disease, anthropogenic influences, and the partially serendipitous factor of propagule availability. Within the complex of environmental factors, several are of special importance in tracing the history of North American plant communities. They include climate; plate tectonics as a mechanism for orogeny, volcanism, land bridges, and terranes; and catastrophes. Each have numerous interacting subcomponents, feedbacks, and amplifiers, and although constraints of format make it necessary to discuss these separately and sequentially, they are interconnected and pertubation of one affects the entire system. Diagrams summarizing these factors are presented at the end of the following sections. The diagrams are not intended as models for, indeed, the single factor of climate could be expanded into a component so vastly complex that it would be counterproductive to a general summary. Similarly, the hydrological cycle, which involves the largest movement of any substance on Earth, cannot be fully treated because a “systems” view of its role in influencing climate is not available (Chahine, 1992) and the roles of water vapor (a greenhouse gas) and cloud cover are just now being quantified (Cess et al., 1995; Ramanathan et al., 1995). Rather, the diagrams illustrate some of the factors and relationships discussed in the text and serve as a reminder of the complex interactive nature of physical and biotic events. Plants are limited in their ecological amplitude. Several important corollaries follow from this observation; one of the most fundamental is that changes in climate cause extinctions promote evolution, and alter the range and habitats of organisms. Because climate plays a central role in the arrangement of modern communities (Gates, 1993; Kareiva et al., 1993; Woodward, 1987) and in the development and distribution of past assemblages (Brenchley, 1984; Crowley and North, 1991; Hecht, 1985a), reference to some elements of general climatology is necessary for understanding the diversification, radiation, and reshuffling of North American paleocommunities during the Late Cretaceous and Cenozoic.


1982 ◽  
Vol 22 (1) ◽  
pp. 227
Author(s):  
O. J. W. Bowering

Recent oil discoveries in the Eromanga Basin in sediments ranging in age from Early Jurassic to Early Cretaceous provide strong evidence for an oil source within the basin.A recent study of the thermal history of Eromanga Basin sediments within the licence areas of Delhi Petroleum Pty Ltd and Santos Limited indicates that generation and primary migration of oil within the basin occurred within a period ranging approximately from late Cretaceous to Early Tertiary and that these events pre-dated the artesian system, which developed in Plio-Pleistocene times. Generation is believed to have occurred within deeper basin depocentres; migration toward the shallower marginal areas followed.The present artesian system is unlikely to have flushed oil out of existing traps. However, there is evidence that the artesian flow was stronger previously, and may have influenced secondary migration of oil. A mound spring has furnished evidence of possible migration to the western margin of the basin.


1991 ◽  
Vol 31 (1) ◽  
pp. 143 ◽  
Author(s):  
D.C. Lowry ◽  
I.M. Longley

The tectonic history of the northern flank of the offshore Gippsland Basin can be divided into three phases:an Early Cretaceous rift phase (120-98 Ma) with deposition of the Strzelecki Group and extension in a northeast-southwest direction.a mid-Cretaceous phase (98-80 Ma) with deposition of the Golden Beach Group and extension in a northwest- southeast direction anda Late Cretaceous to Tertiary sag phase with intermittent compression or wrenching.Previous workers have described the first and third phases. This paper argues for a distinctive second phase with extension at right angles to the first phase. The complex Cretaceous structure in the Kipper-Hammerhead area is interpreted in terms of a model in which transfer faults of the first phase became domino faults of the second phase.


2007 ◽  
Vol 97 (6) ◽  
pp. 1331-1352 ◽  
Author(s):  
Krenn Kurt ◽  
Fritz Harald ◽  
Mogessie Aberra ◽  
Schaflechner Johannes

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