Evolution and taxonomic study of the Cretaceous planktic foraminiferal genus Helvetoglobotruncana Reiss, 1957

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doi: 10.2113/gsjfr.44.1.40
Author(s): Huber, Brian T.; Petrizzo, Maria Rose
Author Affiliation(s): Primary:
Smithsonian Institution National Museum of Natural History, Department of Paleobiology, Washington, DC, United States
Other:
Universita degli Studi di Milano, Italy
Volume Title: Journal of Foraminiferal Research
Source: Journal of Foraminiferal Research, 44(1), p.40-57. Publisher: Cushman Foundation for Foraminiferal Research, Ithaca, NY, United States. ISSN: 0096-1191 CODEN: JFARAH
Note: In English. NSF Grant EAR-0641956. 76 refs.; illus., incl. strat. cols., geol. sketch map
Summary: The evolution and taxonomy of the planktic foraminifer genus Helvetoglobotruncana Reiss, 1957, are investigated to improve stability in the concepts of the biomarker species Hv. praehelvetica and Hv. helvetica, which have been used to correlate uppermost Cenomanian-middle Turonian (Upper Cretaceous) marine sediments worldwide. The study focuses on exquisitely preserved specimens obtained from Turonian marine claystones drilled on the coastal margin of Tanzania, and these are compared with specimens reported from a number of Cenomanian/Turonian boundary sequences worldwide. Absence of discernable shell recrystallization in the Tanzanian specimens provides an unprecedented opportunity for detailed observations of the external wall texture and wall microstructures, allowing for a more concise characterization of similarities and differences between the two species. Abundance counts of Turonian planktic foraminifer assemblages from one Tanzania borehole reveals that Hv. helvetica occurs in trace abundance early in its range and reaches maximum abundance of 35-45% of the total assemblage shortly before the simultaneous and abrupt extinction of both helvetoglobotruncanid species. The ratio between Hv. helvetica and Hv. praehelvetica increases gradually up-section, with a 1:1 ratio reached nearly halfway above the lowest occurrence level of Hv. helvetica and 9:1 dominance by Hv. helvetica near the top of its range. The helvetoglobotruncanid and mixed whiteinellid species yield δ13C and δ18O values that are nearly identical and slightly more enriched in δ18O than co-occurring Globoheterohelix paraglobulosa, and they are slightly more enriched in d13C and more depleted in δ18O than co-occurring species of Dicarinella and Praeglobotruncana. These isotopic results indicate that helvetoglobotruncanids lived at relatively shallow depths in the mixed layer. Using an age model developed for the Rock Canyon Anticline Cenomanian/Turonian Global Stratotype Section and Point (GSSP) sequence near Pueblo, Colorado, the age of the first occurrence of Hv. helvetica is calculated as 93.52 Ma. The extinction of Hv. helvetica has not been properly calibrated, but it must be younger than 92.77 Ma, which is the age of its occurrence at the top of the Rock Canyon Anticline GSSP section.
Year of Publication: 2014
Research Program: DSDP Deep Sea Drilling Project
IPOD International Phase of Ocean Drilling
ODP Ocean Drilling Program
Key Words: 02 Geochemistry; 10 Paleontology, Invertebrate; 12 Stratigraphy, Historical Geology and Paleoecology; Africa; Biologic evolution; Biostratigraphy; Biozones; C-13/C-12; Carbon; Cretaceous; DSDP Site 463; Deep Sea Drilling Project; East Africa; Exmouth Plateau; First occurrence; Foraminifera; Hedbergellidae; Helvetoglobotruncana; IPOD; Indian Ocean; Invertebrata; Isotope ratios; Isotopes; Leg 122; Leg 62; Lindi Tanzania; Lithostratigraphy; Mesozoic; Microfossils; Mid-Pacific Mountains; Morphology; North Pacific; Northwest Pacific; O-18/O-16; ODP Site 763; Ocean Drilling Program; Oxygen; Pacific Ocean; Planktonic taxa; Protista; SEM data; Stable isotopes; Tanzania; Tanzanian Drilling Project; Taxonomy; Tests; Turonian; Upper Cretaceous; West Pacific
Coordinates: S203512 S203511 E1121232 E1121231
N212101 N212101 E1744004 E1744004
S100000 S100000 E0394300 E0394300
Record ID: 2014011357
Copyright Information: GeoRef, Copyright 2017 American Geosciences Institute. Abstract, Copyright, Cushman Foundation for Foraminiferal Research, Reference includes data from GeoScienceWorld, Alexandria, VA, United States