Morphological variability of Globorotalia menardii in DSDP Sites 68-502 and 68-503


Autoria(s): Knappertsbusch, Michael W
Cobertura

MEDIAN LATITUDE: 7.773363 * MEDIAN LONGITUDE: -87.507877 * SOUTH-BOUND LATITUDE: 4.050700 * WEST-BOUND LONGITUDE: -95.636800 * NORTH-BOUND LATITUDE: 11.491800 * EAST-BOUND LONGITUDE: -79.378200 * DATE/TIME START: 1979-08-16T00:00:00 * DATE/TIME END: 1979-09-06T00:00:00

Data(s)

03/08/2007

Resumo

Variability in the test of Globorotalia menardii during the past 8 million years has been investigated at DSDP Site 502A (Caribbean Sea) and DSDP Site 503A (Eastern Equatorial Pacific). Measurements were made of spire height (delta x), maximum diameter (delta y), the tangent angles of the upper and lower peripheral keels (phi 1, phi 2, respectively), the number of chambers in the final whorl, and the area of the silhouette in keel view. Four morphotypes alpha, beta, gamma, and delta were distinguished. Morphotype alpha was found in strata ranging in age from the Late Miocene through the Holocene. It shows a continuous increase in delta x and delta y until the Late Pleistocene. During and after the final closure of the ancient Central American Seaway (between 2.4 Ma and 1.8 Ma) there was a rapid increase in the area of the test in keel view. At the Caribbean Sea site, morphotype beta evolved during the past 0.22 Ma. It is less inflated than alpha and has a more delicate test. In the morphospace of delta x vs. delta y, morphotypes alpha and beta can be distinguished by a separation line delta y = 3.2 * delta x - 160 (delta x and delta y in µm). Plots of morphotype alpha are below that line, those of beta are above it. Morphotype alpha is taken to be Globorotalia menardii menardii Parker, Jones & Brady (1865) and includes G. menardii 'A' Bolli (1970). Morphotype beta is identified as G. menardii cultrata (d'Orbigny). Morphotypes gamma and delta are extinct Upper Miocene to Pliocene forms which evolved from morphotype alpha. They have a narrower phi 1 angle and more chambers (>=7) than morphotype alpha commonly with 5 to 6 chambers (7 in transitional forms). In contemporaneous samples morphotype delta can be distinguished from gamma by a smaller value of phi 1 and 8 or more chambers in the final whorl. Morphotype gamma is taken to be G. limbata (Fornasini, 1902) and includes the junior synonym G. menardii 'B' Bolli (1970). Morphotype delta is G. multicamerata Cushman & Jarvis (1930). With the exception of the Late Pleistocene development of G. menardii cultrataonly in the Caribbean the morphological changes of G. menardii at DSDP Sites 502A and 503A are similar. The development from the ancestral G. menardii menardii of the G. limbata - G. multicamerata lineage during the Pliocene and of G. menardii cultrata during the Late Pleistocene suggests responses at the two sites to a changing palaeoceanography during and after the formation of the Isthmus of Panama.

Formato

application/zip, 4 datasets

Identificador

https://doi.pangaea.de/10.1594/PANGAEA.863580

doi:10.1594/PANGAEA.863580

Idioma(s)

en

Publicador

PANGAEA

Relação

Knappertsbusch, Michael W: Archive to: Raw data to Knappertsbusch, M. (2007). Morphological variability of Globorotalia menardii (planktonic foraminifera) in two DSDP cores from the Caribbean Sea and Eastern Equatorial Pacific. https://store.pangaea.de/Publications/KnappertsbuschM_2007/DSDP_502_503.zip (Zip file to file archive for "download all". Be carefull size is 1.48 GB!)

Documentation to: Raw data to Knappertsbusch, M. (2007). Morphological variability of Globorotalia menardii (planktonic foraminifera) in two DSDP cores from the Caribbean Sea and Eastern Equatorial Pacific (URI: https://store.pangaea.de/Publications/KnappertsbuschM_2007/INTRODUCTION.htm)

Direitos

CC-BY: Creative Commons Attribution 3.0 Unported

Access constraints: unrestricted

Fonte

Supplement to: Knappertsbusch, Michael W (2007): Morphological variability of Globorotalia menardii (planktonic foraminifera) in two DSDP cores from the Caribbean Sea and the Eastern Equatorial Pacific. Carnets de Geologie, CG2007_A04, http://paleopolis.rediris.es/cg/CG2007_A04/index.html

Palavras-Chave #Age; AGE; Age model, Berggren et al (1995) BKSA95; Deep Sea Drilling Project; Depth; DEPTH, sediment/rock; DSDP; Event; File name; File size; Label; mbsf; ODP sample designation; Sample code/label; Uniform resource locator/link to file; URL file
Tipo

Dataset