Integrated Late Eocene-Oligocene Stratigraphy of the Alabama Coastal Plain: Correlation of Hiatuses and Stratal Surfaces to Glacioeustatic Lowerings

We integrated strontium and oxygen isotopic, biostratigraphic, and magnetostratigraphic studies of two upper Eocene-Oligocene boreholes drilled near Bay Minette and St. Stephens Quarry (SSQ), Alabama. Continuous coring provided fresh, unweathered material for magnetostratigraphic studies, minimizing problems reported from nearby outcrops. Difficulties with each technique were encountered because of diagenesis, absence of marker fossils, and the presence of unconformities; however, by integrating results from isotopic stratigraphy, biostratigraphy, and magnetostratigraphy, we correlated these relatively shallow-water deposits to the geomagnetic polarity time scale (GPTS). At the SSQ borehole, the upper Eocene to lower Oligocene section is apparently complete within our stratigraphic resolution (0.2-0.5 m.y.), allowing us to estimate the ages of several stratal surfaces. Late Eocene Sr isotope age estimates are as expected at the SSQ borehole, but Oligocene ages are ~1 m.y. older than expected due to diagenesis. At the Bay Minette borehole, a latest Eocene-earliest Oligocene and a late early Oligocene hiatus were detected. We correlate these two hiatuses and stratal surfaces at SSQ with global δ^18O increases inferred to represent glacioeustatic lowerings and with evidence for hiatuses on other continental margins: (1) a distinct disconformity at the base of the Chickasawhay Limestone at both boreholes and a hiatus at Bay Minette correlates with a global δ^18O increase; we revise the age of this surface (equivalent to the TB 1.1 sequence boundary) making it ~2 m.y. older than previously reported; and (2) a surface at the top of the Shubuta Member (lowermost Oligocene) has been interpreted both as a condensed section and a disconformity; this surface at SSQ and a hiatus at Bay Minette correlate with a sharp global δ^18O increase and with hiatuses on the New Jersey and Irish margins. The timing of the hiatuses and stratal surfaces correlates with the inflection of the δ^18O increases and not with the maximum values, supporting models that indicate that unconformities form during the maximum rates of sea level fall

Menderes Massif (Western Turkey): structural, metamorphic and magmatic evolution - a synthesis

The Menderes Massif covers large areas in western Turkey. The better understanding of its tectono-metamorphic history would provide insight for the Alpine evolution of western Turkey and the entire eastern Mediterranean region. This paper summarizes the available literature on the metamorphic rocks of western Turkey and that of the Menderes Massif with special reference and emphasis to the papers presented in the special issue

First occurrence of Fe-Mg-carpholite documenting a high-pressure metamorphism in metasediments of the Lycian Nappes, SW Turkey

In the basal thrust sheets of the Lycian nappes fresh Fe-Mg-carpholite documents low-grade. high-pressure (HP) metamorphism. Here we describe the first occurrences of this HP indicator mineral in Turkey, its regional distribution and geodynamic consequences. Carpholite and its breakdown products, such as chloritiod and pyrophyllite, occur in the Lycian nappes s.s. Relics of Fe-Mg-carpholite were also found in klippen of Lycian nappe material located on top of the Menderes crystalline massif. The distribution of the Fe-Mg-carpholite and its relies traces an extensive area of HP metamorphism in the sediments of a passive continental margin

Eclogites within the Menderes Massif western Turkey

Metagabbros in the core series of the Menderes Massif, for some time considered as post orogenic Miocene intrusives, revealed a strong poly-metamorphic history. The metagabbro bodies exhibit a pronounced zonation. Within their cores, igneous minerals are still preserved. Coronitic textures are interpreted as results of a high temperature, possibly granulitic overprint. The outer parts of the metagabbro bodies mostly consist of strongly to completely retrograded gamet-amphibo-lites, but occasionally contain relies of eclogites. Petrologic investigations confirmed a high pressure overprint and allowed preliminary P, T estimates (650 degrees C, equal to or greater than 1.3 GPa). The intensity of the HP metamorphism seems to rise from south to north within the Menderes basement, thus pointing to a northward subduction as the cause. The age of the high pressure event still awaits clarification. However, its very existence reanimates the question, how close the relationship between Menderes and the Cyclades evolution might have been. (C) 1997 Elsevier Science B.V

Blueschist relics in the Mesozoic cover series of the Menderes Massif and correlations with Samos Island, Cyclades

In the western part of the Menderes Massif, Selcuk-Dilek Peninsula, relies of Tertiary HP metamorphism under epidote-blueschist facies conditions were recognized in the Mesozoic cover series. This subduction-related high-pressure metamorphism, with temperature of less than 470 degrees C and minimum pressure of about 10 kbar, was subsequently followed by a Barrovian-type overprint under greenschist facies conditions during Late Eocene/Early Oligocene. Based on the lithostratigraphy and the two-fold Tertiary metamorphism, the Mesozoic cover series in this area can be correlated with the Vourliutes unit on Samos Island, belonging to the Cycladic Crystalline Complex