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

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.

2013 ◽  
Vol 16 (2) ◽  
pp. 48-63
Author(s):  
Luan Thi Bui

Up to now, reservoir system in Cuu Long basin have been known including Pre-Tertiary fracture basement, sandstone of lower-Oligocene formation (Porosity from 12 to 16%, permeability from 1 to 250 mD), sandstone of upper-Oligocene formation (Porosity from 12 to 21%, permeability from 2 to 26 mD), sandstone of lower-Miocene formation (Porosity from 14 to 28%, permeability from 1 to 1300 mD). However, the result of evaluation of analysis of data at block 02 is very good oil shows in sandstone of middle-Miocene formation, the gas oil ratios of this oil is from medium to high, predominantly light oil and hydrocacbon have not changed yet. The result of analysis of core samples and petrophysis data of sandstone of middle-Miocene is that porosity is from <10 to 31% and permeability is from 100 to 3066 mD. Following geology structure and combining data of seismic, petrology, stratigraphic and geochemical source rock indicated oil of middle-Miocene was relative with lower-Oligocene and upper-Oligocene. These rocks contain abundant of organic matters that could produce hydrocarbon well. Then, hydrocarbon migrated and accumulated into fold traps in lower and middle-Miocene. Proven reserves 1P (P50) of two reservoir sets BII .2.20 và BII .1.10 is 70.7 MMbbl and proven plus probable reserves 2P(P50) of two reservoirs BII .2.20 và BII .2.30 is 73.11 MMbbl. Discovering oil and gas in middle-Miocene at block 02 openes up new target in exploration of oil and gas field in margin zones of Cuu Long basin.


1996 ◽  
Vol 70 (6) ◽  
pp. 935-940 ◽  
Author(s):  
Claudia J. del Río ◽  
Horacio H. Camacho

Iheringinucula, a new Tertiary genus of the family Nuculidae, is proposed. This taxon is known only from the Patagonian region (Argentina), and its range is from the late Eocene to the early Miocene. Two species are known: Iheringinucula tricesima (Ihering) from the Monte León Formation (upper Oligocene-lower Miocene) and Iheringinucula crassirugata new species from the San Julián Formation (upper Eocene-lower Oligocene?) and the Monte León Formation.


2020 ◽  
Vol 33 (5) ◽  
pp. 1619-1641 ◽  
Author(s):  
Jie Feng ◽  
Tao Lian ◽  
Jun Ying ◽  
Junde Li ◽  
Gen Li

AbstractWhether the state-of-the-art CMIP5 models have different El Niño types and how the degree of modeled El Niño diversity would be impacted by the future global warming are still heavily debated. In this study, cluster analysis is used to investigate El Niño diversity in 30 CMIP5 models. As the method does not rely on any prior knowledge of the patterns of El Niño seen in observations, it provides a practical way to identify the degree of El Niño diversity in models. Under the historical scenario, most models show a poor degree of El Niño diversity in their own model world, primarily due to the lopsided numbers of events belonging to the two modeled El Niño types and the weak compactness of events in each cluster. Four models are found showing significant El Niño diversity, yet none of them captures the longitudinal distributions of the warming centers of the two El Niño types seen in the observations. Heat budget analysis of the sea surface temperature (SST) anomaly suggests that the degree of modeled El Niño diversity is highly related to the climatological zonal SST gradient over the western-central equatorial Pacific in models. As the gradient is weakened in most models under the future high-emission scenario, the degree of modeled El Niño diversity is further reduced in the future. The results indicate that a better simulation of the SST gradient over the western-central equatorial Pacific might allow a more reliable simulation/projection of El Niño diversity in most CMIP5 models.


2002 ◽  
Vol 41 (Part 1, No. 5B) ◽  
pp. 3525-3529 ◽  
Author(s):  
Yong Wang ◽  
Hiroyuki Hachiya ◽  
Toshiaki Nakamura ◽  
Iwao Nakano

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