Date (Publication)

2018-09-21T02:30:00

Cited responsible party

Organisation name	Individual name	Electronic mail address	Role
National Institute of Water and Atmospheric Research (NIWA)		enquiries@niwa.co.nz	Resource provider

Other citation details

The citation in a list of references is: "NIWA [year-of-data-download], [Title], [data-access-URL], accessed [date-of-access]."

Purpose

New Zealand has a large and geologically complex marine Exclusive Economic Zone (EEZ) and extended continental shelf (ECS). Data from ~150 published, unpublished, national and international collections covering >30,000 sediment analyses and observations were compiled and integrated to produce a database (nzSEABED) and series of maps characterising the surficial sediments of the entire New Zealand EEZ-ECS. Sediment grainsize/texture and carbonate distributions show distinct spatial patterns, which can be explained by past and present climate, sea level fluctuations, terrigenous (from the land) sediment flux, tectonics and volcanism, complex bathymetry, oceanography, and diagenesis. The results are compared with previous literature, providing a comprehensive review of the distribution of surficial marine sediments for the New Zealand EEZ-ECS.The sediment samples and data were collected from approximately the 1950-2000s using a range of different sampling methods and analytical methods. The most common methods for sampling surface sediments were grabs, dredges and corers. Other methods included trawls, sleds, diver samples and underwater camera observations and some methods were not recorded. All these methods may yield a biased sample. For example, cores struggle to admit shell, and sediments coarser than gravel. Grainsize analyses were done using a range of methods, from descriptions, sieving and more recently using Xray attenuation and laser techniques. Carbonate analyses were done using descriptions, acid digestion and titration.

The dbSEABED software ( http://instaar.colorado.edu/~jenkinsc/dbseabed/ ) was used to integrate the diverse, heterogeneous collated data. All the data are quality controlled. For analytical quantitative data the values are tested for plausibility. For word-based data, descriptions are parsed and meanings and values are attached to the essential terms. For example, a description of “muddy sand” will be assigned as 40% mud and 60% sand. A sample which is described as “pelagic ooze” (a sample made up of carbonate plankton skeletons), a carbonate content of 90% is attributed. Details are described in Jenkins (1997; 2002) and Buczkowski et al. (2006). The character values are based on calibrations from datasets where both descriptions and analyses are present on thousands of samples (Harff et al., 1997; McMullen et al., 2014).

Processed and integrated sediment data from nzSEABED were imported in to ArcGIS using a Mercator projection in order to allow for seamless interpolations across the 180°meridian. The data was interpolated using ordinary kriging based on the 12 nearest points with a restricted distance of 100 km, and plotted the data on a 1x1 km grid. The predicted standard error (standard deviation for any point) for percent mud for the kriging interpolation is low in well sampled regions such as the continental shelf and Chatham Rise (8-16%), and increases in the more sparsely sampled deep waters (20-24% at >3000 m). It should be noted that we have not included rocks in this database, thus the interpolated sediments will superimpose over rock outcrops.

Credit

NIWA

See:

Bostock et al., 2018. Distribution of surficial sediments in the ocean around New Zealand/Aotearoa. Part A: continental slope and deep ocean. New Zealand Journal of Geology and Geophysics.

Bostock et al., 2018. Distribution of surficial sediments in the ocean around New Zealand/Aotearoa. Part B: continental shelf. New Zealand Journal of Geology and Geophysics.

Status

Completed

Point of contact

Organisation name	Individual name	Electronic mail address	Role
National Institute of Water and Atmospheric Research (NIWA)	Dr Helen Bostock	enquires@niwa.co.nz	Principal investigator

Maintenance and update frequency

Not planned

AODN Geographic Extents Vocabulary

• Global / Oceans | South West Pacific Ocean

Place

• Countries | New Zealand

Theme

• Seafloor | Sediment | Carbonate

Distance

1000   1000 metres

Language

eng

Character set

UTF8

Topic category

• Oceans

Description

New Zealand regional waters, encompassing the Exclusive Economic Zone and the Continental Shelf

Distribution format

Name	Version
Raster	1

OnLine resource

Protocol	Linkage	Name
WWW:LINK-1.0-http--metadata-URL	https://nzodn.nz/geonetwork/srv/en/metadata.show?uuid=c2c8f0a2-2f0a-4deb-a433-56f949300ab5
OGC:WMS-1.1.1-http-get-map	https://nzodn.nz/geoserver/nzodn/wms	nzodn:mud_map
IMOS:AGGREGATION--bodaac	https://nzodn.nz/geoserver/ows	mud_map#url
	http://instaar.colorado.edu/~jenkinsc/dbseabed/

Metadata

File identifier

c2c8f0a2-2f0a-4deb-a433-56f949300ab5 XML

Metadata language

eng

Character set

UTF8

Hierarchy level

Dataset

Date stamp

2018-09-28T02:25:33

Metadata standard name

ISO 19115:2003/19139

Metadata standard version

1.0

Metadata author

Organisation name	Individual name	Electronic mail address	Role
National Institute of Water and Atmospheric Research (NIWA)		enquiries@niwa.co.nz	Custodian