Grain-size parameters of insoluble residues in mixed terrigenous-skeletal carbonate sediments and sedimentary rocks: some New Zealand examples

Sedimentology ◽  
1977 ◽  
Vol 24 (1) ◽  
pp. 31-52 ◽  
Author(s):  
CAMPBELL S. NELSON
Keyword(s):  
Grain Size ◽  
New Zealand ◽  
Sedimentary Rocks ◽  
Carbonate Sediments ◽  
Grain Size Parameters

Mineralogical and textural discrimination of loess derived from a tephra near Rotorua, New Zealand

Soil Research ◽  
1988 ◽  
Vol 26 (2) ◽  
pp. 301 ◽  
Author(s):  
LA Benny ◽  
NM Kennedy ◽  
JH Kirkman ◽  
RB Stewart
Keyword(s):  
Grain Size ◽  
New Zealand ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Field Observations ◽  
Mean Grain Size ◽  
Mean Size ◽  
The Mean ◽  
Grain Size Parameters

Grain size parameters and clay mineralogical analyses were used to characterize and compare Okareka Ash and post-Okareka tephric loess sampled at eight sites on a transect in Rotorua district, North Island, New Zealand. Grain size distribution analyses show consistently lower mean size and better sorting of the tephric loess compared with the Okareka Ash. The mean grain size of the loess is strongly influenced by the mean grain size of the tephra. Trends in the distribution of biotite and halloysite support the grain size distribution analyses. Taken with field observations, the analytical evidence allows differentiation between Okareka Ash and overlying associated tephric loess.

Grain-size parameters of marine sediments

Oceanology ◽  
2006 ◽  
Vol 46 (3) ◽  
pp. 430-439
Author(s):  
T. N. Alekseeva ◽  
V. N. Sval’nov
Keyword(s):  
Grain Size ◽  
Marine Sediments ◽  
Grain Size Parameters

scholarly journals Actuopaleontological investigations of shallow water Red Sea echinoids

1992 ◽  
Vol 6 ◽  
pp. 220-220
Author(s):  
James H. Nebelsick
Keyword(s):  
Grain Size ◽  
Red Sea ◽  
Distribution Patterns ◽  
Close Correlation ◽  
Time Averaging ◽  
Multivariate Statistical ◽  
Cryptic Habitats ◽  
Echinometra Mathaei ◽  
Grain Size Parameters ◽  
Diadema Setosum

The regular and irregular echinoid fauna of the Northern Bay of Safaga (Red Sea, Egypt) has been investigated within the framework of an actuopaleontological study of the flora, fauna, sediments and facies. The distribution of echinoids has been compared to grain size parameters as well as to the distribution of other organisms.The study area (ca. 10 × 7 km) was investigated using SCUBA-diving techniques along 55 transects with a total length of 126 km. Echinoid presence was quantified using weights of fragments (2 mm) originating from 67 standardized bulk samples distributed throughout the Bay. The complex morphology of the echinoid test and the spines allow the identification of fragmented material upon comparison to complete specimens. The resulting data was analyzed using correlation techniques as well as Q and R-mode multivariate statistical analysis. This method counters the difficulties originating from the cryptic habitats and patchy distributions.The results of the analysis show that echinoid distribution can be analyzed for both regular and irregular wchinoid taxa despite taphonomic bias and restrictions imposed by the analytic method. Time averaging in fact counters the difficulties arising from the patchy distributions of echinoids. There is a close correlation of echinoid distribution to sedimentary and bottom facies as well as to grain size parameters and other environmental factors. The distribution of irregular echinoids is highly differentiated with coarse coastal sand dominated by Clypeaster sp., Echinodiscus auritus, Fibularia ovulum, and Lovenia elongata; muddy sands by Laganum depressum, Clypeaster sp. and Echinocyamus crispus; and muds by members of the Schizasteridae. Regular echinoids, mostly Eucidaris metularia, Echinometra mathaei, Tripneustes gratilla, Heterocentrotus mammillatus and Diadema setosum, dominate the sediments found within, or near reefs, coral carpets and patch reefs.The methodology used in this actuopaleontological investigation should be useful in recognizing the distribution patterns of ancient echinoid faunas, especially in light of the significance of regular echinoids in the bioerosion of reefs and irregular echinoids in the bioturbation of sediments.

scholarly journals Iridium anomaly in the cretaceous-paleogene boundary at Højerup (Stevns Klint, Denmark) and Woodside Creek (New Zealand): The question of an enormous proportion of extraterrestrial component

2012 ◽  
Vol 77 (2) ◽  
pp. 247-255 ◽  
Author(s):  
Pavle Premovic ◽  
Budimir Ilic ◽  
Milos Djordjevic
Keyword(s):  
New Zealand ◽  
Boundary Layers ◽  
Sedimentary Rocks ◽  
Iridium Anomaly

The Cretaceous-Paleogene boundary clays at H?jerup and Woodside Creek show anomalous enrichments of iridium compared with the marine sedimentary rocks. For the average iridium content of 465 ppb in CI chondrite the estimate of the carbonaceous chondritic proportions in the decarbonated iridium-rich boundary layers, based on the integrated iridium fluencies, is about 26% at H?jerup and 65% at Woodside Creek. These proportions are most likely too high due to a significant Ir influx from the nearby marine or continental site to these sections.

Notes on Petrographic Methods

1923 ◽  
Vol 60 (4) ◽  
pp. 165-168
Author(s):  
P. G. H. Boswell
Keyword(s):  
Grain Size ◽  
Sedimentary Rocks ◽  
Work Done

Many workers in the domain of the petrology of sedimentary rocks will welcome the article by Dr. Rastall in the Geological Magazine for January, 1923, and will appreciate the fact that certain notes therein help to make clear what may or may not reasonably be expected from this branch of geology. Judging from what has been said and written from time to time, I fear there is some amount of misconception as to what is being and has been achieved by the study of the rarer minerals and grain-size of sediments. As Dr. Rastall has paid me the compliment of referring to certain work with which I was concerned, in part during the war, it may be of interest and service if I indicate briefly the character of some of the work done and the utility of the petrographic methods adopted.

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