Geology topics

Research about equatorial Pacific Ocean

Source-linked reports with geographic coverage including equatorial Pacific Ocean.

4 recordsLinked to original sources

USGS2005

Diatom biochronology for the early Miocene of the equatorial Pacific

The latest Oligocene and early Miocene diatom biostratigraphy (24.4 to 16.9 Ma) of equatorial Pacific ODP Site 199-1219 is documented and tied to paleomagnetic stratigraphy in 69 samples, allowing an average age resolution of about 100 kyrs. An updated taxonomy is provided and most of the 71 taxa are illustrated in 9 photographic plates. The equatorial Pacific diatom zonation for the latest Oligocene and early Miocene is updated: the Nitzschia maleinterpretaria Partial Range Zone is newly proposed to replace the Triceratium pileus Interval Zone and part of the Craspedodiscus elegans Partial Range Zone, and the C. elegans Zone is modified to be an interval zone. Absolute ages of 62 datum levels are estimated and compared with age estimates from elsewhere in the equatorial Pacific, as well as from the North Pacific and Southern Ocean. It is likely that many of these datum levels will be useful for correlations between the equatorial Pacific and higher latitude regions.

Stratigraphy↗

USGS2005

Scanning electron microscope studies of some early Miocene diatoms from the equatorial Pacific Ocean with descriptions of two new species, Actinocyclus jouseae Barron and Actinocyclus nigriniae Barron

Scanning electron microscope (SEM) and light microscope (LM) studies are used to propose and describe two new species, Actinocyclus jouseae Barron , sp. nov. and Actinocyclus nigriniae Barron , sp. nov. from lower Miocene sediments from equatorial Pacific ODP Site 1219. Parallel SEM and LM studies reveal that Thalassiosira bukryi Barron should be transferred to Azpeitia and suggest that Actinocyclus barronii Radionova is likely to be a variety of A. radionovae Barron

Proceedings of the California Academy of Sciences ↗

USGS2004

Oligocene and earliest Miocene diatom biostratigraphy of ODP leg 199 site 1220, equatorial Pacific

Completion of studies on material collected during Ocean Drilling Program Leg 199 at Site 1220 in the equatorial Pacific allows calibration of the ranges of >35 stratigraphically important diatoms to paleomagnetic stratigraphy for the Oligocene and earliest Miocene (~33.5–21.5 Ma). The taxonomy of these taxa is reviewed, and age estimates of their first and last occurrences are compiled. The diatom zonation for the Oligocene and earliest Miocene of the equatorial Pacific is revised and correlated with paleomagnetic stratigraphy. This biostratigraphy is likely to be applicable throughout the low-latitude regions of the world's oceans.

Proceedings of the Ocean Drilling Program: Scienti↗

USGS1998

The Holocene sea-level highstand in the equatorial Pacific: Analysis of the insular paleosea-level database

A review of the literature provides 92 estimates of the middle to late Holocene sea-level highstand on Pacific Islands. These data generally support geophysical model calculations that predict a +1 to 3 m relative sea-level highstand on oceanic islands due to the Earth’s rheological response to the melting of the last continental ice sheets and subsequent redistribution of meltwater. Both predictions and observations indicate sea level was higher than present in the equatorial Pacific between 5000 and 1500 y B.P. A non-linear relationship exists between the age and elevation of the highstand peak, suggesting that different rates of isostatic adjustment may occur in the Pacific, with the highest rates of sea-level fall following the highstand near the equator. It is important to resolve detailed sea-level histories from insular sites to test and refine models of climatic, oceanographic, and geophysical processes including hydroisostasy, equatorial ocean siphoning, and lithospheric flexure that are invoked as mechanisms affecting relative sea-level position. We use a select subset of the available database meeting specific criteria to examine model relationships of paleosea-surface topography. This new evaluated database of paleosea-level positions is also validated for testing and constraining geophysical model predictions of past and present sea-level variations.

Coral Reefs↗