A Late Cretaceous Molluscan-Microfossil Biochronology for the West Coast, and Its Application to Sequence Stratigraphic Analysis of the Great Valley Sequence: ABSTRACT

AAPG Bulletin ◽  
1995 ◽  
Vol 79 ◽  
Author(s):  
William P. Elder
2006 ◽  
Vol 75 (03-04) ◽  
pp. 121-132 ◽  
Author(s):  
René H.B. Fraaije ◽  
Francisco J. Vega ◽  
Barry W.M. van Bakel ◽  
Luis M. Garibay-Romero

Two new brachyuran species are described for the Upper Cretaceous Mexcala Formation, Guerrero State, Mexico. Longusorbis quadratus new species (Coniacian, Temalac region) is the oldest and southernmost record for the genus. Xanthosia zoquiapensis new species (Campanian, Zoquiapa region) is the first record for the genus in Mexico. In addition, the age for Costacopluma bishopi Vega and Feldmann is discussed (Coniacian, Temalac region) and represents the oldest and southernmost record for Cretaceous representatives of this genus in North America. All specimens are considerably smaller compared to other species of the same genera and are interpreted as the first example of brachyuran dwarfism in the geological record. These species add new insight into possible migratory routes during the Late Cretaceous. Within Longusorbis, a northwestern migratory route is documented from the Coniacian in Mexico to the Campanian - Maastrichtian of the west coast of North America (Canada), whereas within the genus Xanthosia, a western migratory route from the Albian of Europe to the Campanian of Mexico is indicated. Costacopluma migrated east and north to the west coast of Africa, southeast North America and Greenland.


2004 ◽  
Vol 44 (1) ◽  
pp. 269 ◽  
Author(s):  
J.M. Benson ◽  
S.J. Brealey ◽  
C.W. Luxton ◽  
P.F. Walshe ◽  
N.P. Tupper

Regional seismic and sequence stratigraphic analysis of the Browse Basin identified a new Late Cretaceous play fairway involving ponded turbidite systems deposited within confined basins. This work highlighted the potential for isolated sandstone reservoirs in the Middle Campanian sequence of the Caswell Sub-basin. Extensional faults were expected to provide vertical conduits for charge from underlying Early Cretaceous source rocks.The play concept was tested by the drilling of two exploration wells in 2001. The Carbine prospect was a potential stratigraphic trap involving deposition of turbidite sandstones within a localised basin set up by slumping in an intra-slope setting. Carbine–1 penetrated a 77 m thick section of high quality, 100% net-to-gross sandstone but failed to encounter hydrocarbons.A similar ponded turbidite model was invoked for the Marabou prospect although in this case the confined basin was controlled by pre-existing topography at the toe of the slope. The trapping mechanism for Marabou was largely stratigraphic although a small area of anticlinal closure was present. Marabou–1 penetrated 102 m of good quality sandstone with elevated gas readings over the uppermost 22 m. Borehole problems prevented the acquisition of wireline logs or testing but it appears likely that the well penetrated a sub-commercial hydrocarbon column restricted to the four-way dip closure.The well results confirmed the presence of ponded turbidite systems with excellent reservoir characteristics. Further work is required, however, to address the critical risks associated with hydrocarbon migration and updip seal. Nevertheless, ponded turbidite systems remain attractive exploration targets particularly in basins where updip seal is assisted by structuring and where the reservoirs are intercalated with prolific source rocks.


2016 ◽  
Vol 546 ◽  
pp. 31-45 ◽  
Author(s):  
E Infantes ◽  
L Eriander ◽  
PO Moksnes
Keyword(s):  

Author(s):  
S.M. Thomas ◽  
M.H.Beare C.D. Ford ◽  
V. Rietveld

Humping/hollowing and flipping are land development practices widely used on the West Coast to overcome waterlogging constraints to pasture production. However, there is very limited information about how the resulting "new" soils function and how their properties change over time following these extreme modifications. We hypothesised that soil quality will improve in response to organic matter inputs from plants and excreta, which will in turn increase nutrient availability. We tested this hypothesis by quantifying the soil organic matter and nutrient content of soils at different stages of development after modification. We observed improvements in soil quality with increasing time following soil modification under both land development practices. Total soil C and N values were very low following flipping, but over 8 years these values had increased nearly five-fold. Other indicators of organic matter quality such as hot water extractable C (HWC) and anaerobically mineralisable N (AMN) showed similar increases. With large capital applications of superphosphate fertiliser to flipped soils in the first year and regular applications of maintenance fertiliser, Olsen P levels also increased from values


2016 ◽  
Vol 93 (1) ◽  
pp. 26-44
Author(s):  
Larry Schweikart ◽  
Lynne Pierson Doti

In Gold Rush–era California, banking and the financial sector evolved in often distinctive ways because of the Gold Rush economy. More importantly, the abundance of gold on the West Coast provided an interesting test case for some of the critical economic arguments of the day, especially for those deriving from the descending—but still powerful—positions of the “hard money” Jacksonians.


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