The Middle Proterozoic Jacobsville Sandstone, located on the upper peninsula, Michigan, is the youngest rift- related sedimentary unit in the 1.1 Ga Midcontinent rift. Although outcrops of the Jacobsville Sandstone along the Lake Superior shoreline and in river gorges are well studied, these outcrops represent stratigraphically only the upper 300-400 feet of the estimated 9,000 feet thick Jacobsville Sandstone. I used drill cores and newly-studied outcrop samples; 1) to characterize stratigraphically continuous sections; 2) to compare the Jacobsville Sandstone in subsurface with the Jacobsville Sandstone in outcrop; 3) to identify lateral and vertical variations in texture and petrographic composition within the Jacobsville Sandstone; and 4) to determine petrographic provenance of the Jacobsville Sandstone.
Metamorphism in the Ollo de Sapo Antiform, part of the Variscan Orogen in NW Spain, was controlled by local, complex interactions of deformation, granitoid intrusions, and regional low pressure metamorphic (LPM) gradient. Detailed analysis of mineral parageneses, in conjunction with geothermobarometry and one-dimensional thermal modeling, have been used to constrain pressure-temperature-deformation (P-T-D) paths for rocks in the antiform.
It is recognized that the ecology of planktonic foraminiferal assemblages provides information about the chemical and physical properties of the water in which they live. Their areal and vertical distributions in the water column and in deep-sea sediments may be used to derive oceanographic and climatic models of Recent and past oceans.
A stratigraphic and paleontological analysis of 303 samples of Paleocene sediments of the eastern Gulf Coastal Plain of Mississippi, Alabama, and Georgia provided the basis for a geochronologic, quantitative paleoecologic, and paleoceanographic model.