Radiolarian Biostratigraphy and Faunal Turnover across the Early/Middle Miocene Boundary in the Equatorial Pacific

2019 ◽  
Vol 23 (4) ◽  
pp. 245 ◽  
Author(s):  
Shin-Ichi Kamikuri ◽  
Theodore C. Moore ◽  
Hiroki Matsui ◽  
Hiroshi Nishi
Keyword(s):  
Middle Miocene ◽  
Equatorial Pacific ◽  
Faunal Turnover ◽  
Radiolarian Biostratigraphy

Late Neogene–Quaternary Planktic Foraminiferal Biostratigraphy and Biochronology from ODP Site 807A, Ontong Java Plateau, Western Equatorial Pacific

2020 ◽  
Vol 50 (2) ◽  
pp. 111-127
Author(s):  
Tushar Kaushik ◽  
Ashutosh Kumar Singh ◽  
Devesh Kumar Sinha
Keyword(s):  
Equatorial Pacific ◽  
Ocean Drilling Program ◽  
Ontong Java Plateau ◽  
Faunal Turnover ◽  
Ocean Drilling ◽  
Late Neogene ◽  
Western Equatorial Pacific ◽  
Globorotalia Truncatulinoides ◽  
Oceanographic Conditions ◽  
Foraminiferal Biostratigraphy

ABSTRACT A biostratigraphic and biochronological study from the late Neogene–Quaternary section of Ocean Drilling Program (ODP) Site 807A, located on the Ontong Java Plateau, western equatorial Pacific, revealed 50 planktic foraminiferal events, enabling the identification of eight late Neogene–Quaternary biozones, from the Globorotalia plesiotumida Interval Zone to the Globorotalia truncatulinoides Interval Zone. A significant faunal turnover (17 events) from late Pliocene identified in cores 7 and 8, between 70 and 55 meters below seafloor (mbsf), and spanning 0.67 million years (Myr). This noteworthy turnover may be the result of a shift in oceanographic conditions pertaining to the closure of the Indo–Pacific Seaway, followed by the Northern Hemisphere Glaciation. This study provides a high resolution biostratigraphic and biochronological framework for ODP Site 807A that will aid in correlation and timing the various paleoceanographic changes over the last 6 million years in the western equatorial Pacific.

Middle Miocene to Pleistocene Planktonic Foraminiferal Biostratigraphy in the Eastern Equatorial Pacific Ocean

2013 ◽  
Vol 17 (1) ◽  
pp. 91-109 ◽  
Author(s):  
Hiroki Hayashi ◽  
Kyoko Idemitsu ◽  
Bridget S. Wade ◽  
Yuki Idehara ◽  
Katsunori Kimoto ◽  
...  
Keyword(s):  
Pacific Ocean ◽  
Middle Miocene ◽  
Equatorial Pacific ◽  
Equatorial Pacific Ocean ◽  
Eastern Equatorial Pacific ◽  
Eastern Equatorial Pacific Ocean ◽  
Foraminiferal Biostratigraphy

scholarly journals The Late Eocene – Recent <i>Bradleya johnsoni</i> Benson lineage (Crustacea, Ostracoda) in the Central Equatorial Pacific

1988 ◽  
Vol 7 (2) ◽  
pp. 187-199 ◽  
Author(s):  
P. Lewis Steineck ◽  
David Yozzo
Keyword(s):  
Middle Miocene ◽  
Late Eocene ◽  
Equatorial Pacific ◽  
General Increase ◽  
Reticular Pattern ◽  
Lower Oligocene ◽  
Upper Oligocene ◽  
Central Equatorial Pacific ◽  
Stratigraphic Ranges ◽  
Direct Ancestor

Abstract. Three stratigraphically successive species of Bradleya Hornibrook, 1952 from abyssal sediments of the central equatorial Pacific (Leg 85, Deep Sea Drilling Project) form an unbranching evolutionary sequence designated as the B. johnsoni Benson lineage. These taxa are B. sp. 1 (Lower Oligocene), B. johnsoni (Upper Oligocene – Middle Miocene) and B. thomasi n. sp. (Upper Miocene – Recent). A shared synapomorphic character, the posterior bridge complex, establishes the kinship of these species. Their stratigraphic ranges and a traceable series of changes in the organisation and mass of the reticulum are consistent with the hypothesis of direct ancestor/descendant relationships between them. Bradleya johnsoni is distinguished from B. sp. 1 by the appearance of new primary muri in the posteroventral region and by a general increase in reticular mass. In B. thomasi, the overall reticular pattern is maintained but it becomes more delicate and less rectilinear. Each species of this lineage shows similar variation in the posteroventral reticulum.

scholarly journals Were late Gomphotheres (Plio-Pleistocene) of the Siwaliks at more Stress as Compared to early Gomphotheres (middle to late Miocene)?

2020 ◽  
Vol 7 (4) ◽  
pp. 117-130
Author(s):  
MUHAMMAD AMEEN ◽  
ABDUL MAJID KHAN ◽  
MUHAMMAD TAHIR WASEEM ◽  
RANA MANZOOR AHMAD ◽  
MUHAMMAD IMRAN ◽  
...  
Keyword(s):  
Late Miocene ◽  
Middle Miocene ◽  
Time Span ◽  
Middle Pleistocene ◽  
Faunal Turnover ◽  
Ecological Stress ◽  
Vegetational Change ◽  
Linear Enamel Hypoplasia ◽  
Ecological Changes ◽  
Aridity Indices

Gomphotheres existed in the Siwaliks from the middle Miocene (14.2Ma) to the middle Pleistocene (0.8Ma) and became extinct later on. In this paper, we tried to discuss the reasons of such extinction of gomphotheres in the lower Pleistocene time span by considering Linear Enamel Hypoplasia (LEH) among 114 isolated tooth samples to assess whether ecological changes correlate with the stress factor in gomphotheres. For this purpose, the Siwalik gomphotheres were divided into two Groups viz. early gomphotheres (middle Miocene to late Miocene) and late gomphotheres (Pliocene to middle Pleistocene). We presented the hypothesis, that as the gomphotheres are characterized by the brachydonty and relied on browsing for their feeding while inhabiting the semi forest land setting thus, expected to have higher stress in Plio-Pleistocene time span as vegetational change around ~6 Ma may have exerted stress on late gomphotheres. The results for the occurrence of frequency of LEH indicated severe ecological stress in late gomphotheres (33%). The significant differences were found (P < 0.05) among the early gomphotheres and late gomphotheres which can be correlated to the vegetational change from C3 to C4, higher aridity indices and intensified seasonality after the late Miocene vegetational shift which may have resulted in substantial faunal turnover, extinction and speciation. We assume that such palaeoecological changes forced a competition with more pronounced grazers like of family Elephantidae and Bovidae resulting in extinction of gomphotheres during the late Pleistocene in the Siwaliks of Pakistan.

scholarly journals Minimal influence of recrystallization on middle Miocene benthic foraminiferal stable isotope stratigraphy in the eastern equatorial Pacific

2016 ◽  
Vol 31 (1) ◽  
pp. 98-114 ◽  
Author(s):  
Janett Voigt ◽  
Ed C. Hathorne ◽  
Martin Frank ◽  
Ann Holbourn
Keyword(s):  
Stable Isotope ◽  
Middle Miocene ◽  
Equatorial Pacific ◽  
Eastern Equatorial Pacific ◽  
Isotope Stratigraphy ◽  
Stable Isotope Stratigraphy
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