NT
Type of resources
Keywords
Publication year
Scale
Topics
-
Baseline information on biodiversity and habitats is required to manage Australia's northern tropical marine estate. This study aims to develop an improved understanding of seafloor environments of the Timor Sea. Clustering methods were applied to a large dataset comprising physical and geochemical variables which describe organic matter (OM) reactivity/quantity/source and geochemical processes. Infauna data were used to assess different groupings. Clusters based on physical/geochemical data discriminated infauna better than geomorphic features. Major variations amongst clusters included grainsize and a cross-shelf transition in from authigenic-Mn /As enrichments (inner shelf) to authigenic-P enrichment (outer shelf). Groups comprising raised features had the highest reactive OM concentrations (e.g. low chlorin indices and C:N-ratios, and high k) and benthic algal '13C signatures. Surface area normalised OM concentrations higher than continental shelf norms were observed in association with: (i) low -15N, inferring Trichodesmium input; and (ii) pockmarks, which impart bottom-up controls on seabed chemistry and cause inconsistencies between bulk and pigment OM pools. Low Shannon-Wiener diversity occurred in association with low redox and porewater pH and evidence for high energy. Highest beta-diversity was observed at euphotic depths. Geochemical data and clustering methods used here provide insight into ecosystem processes influencing biodiversity patterns in the region.
-
Total magnetic intensity (TMI) data measures variations in the intensity of the Earth's magnetic field caused by the contrasting content of rock-forming minerals in the Earth crust. Magnetic anomalies can be either positive (field stronger than normal) or negative (field weaker) depending on the susceptibility of the rock. The data are processed via standard methods to ensure the response recorded is that due only to the rocks in the ground. The results produce datasets that can be interpreted to reveal the geological structure of the sub-surface. The processed data is checked for quality by GA geophysicists to ensure that the final data released by GA are fit-for-purpose. These line dataset from the Groote Eyelandt, NT, 1993 survey were acquired in 1993 by the NT Government, and consisted of 16092 line-kilometres of data at 500m line spacing and 100m terrain clearance. To constrain long wavelengths in the data, an independent data set, the Australia-wide Airborne Geophysical Survey (AWAGS) airborne magnetic data, was used to control the base levels of the survey data. This survey data is essentially levelled to AWAGS.
-
The radiometric, or gamma-ray spectrometric method, measures the natural variations in the gamma-rays detected near the Earth's surface as the result of the natural radioactive decay of potassium (K), uranium (U) and thorium (Th). The data collected are processed via standard methods to ensure the response recorded is that due only to the rocks in the ground. The results produce datasets that can be interpreted to reveal the geological structure of the sub-surface. The processed data is checked for quality by GA geophysicists to ensure that the final data released by GA are fit-for-purpose. This Groote Eyelandt (Bickerton), NT, 1993 (P609), radiometric line data, AWAGS levelled were acquired in 1993 by the NT Government, and consisted of 16092 line-kilometres of data at 500m line spacing and 100m terrain clearance. To constrain long wavelengths in the data, an independent data set, the Australia-wide Airborne Geophysical Survey (AWAGS) airborne magnetic data, was used to control the base levels of the survey data. This survey data is essentially levelled to AWAGS.
-
Total magnetic intensity (TMI) data measures variations in the intensity of the Earth's magnetic field caused by the contrasting content of rock-forming minerals in the Earth crust. Magnetic anomalies can be either positive (field stronger than normal) or negative (field weaker) depending on the susceptibility of the rock. The data are processed via standard methods to ensure the response recorded is that due only to the rocks in the ground. The results produce datasets that can be interpreted to reveal the geological structure of the sub-surface. The processed data is checked for quality by GA geophysicists to ensure that the final data released by GA are fit-for-purpose. These line dataset from the Mount Peake, NT, 1995 survey were acquired in 1995 by the NT Government, and consisted of 60332 line-kilometres of data at 500m line spacing and 100m terrain clearance. To constrain long wavelengths in the data, an independent data set, the Australia-wide Airborne Geophysical Survey (AWAGS) airborne magnetic data, was used to control the base levels of the survey data. This survey data is essentially levelled to AWAGS.
-
Gravity data measures small changes in gravity due to changes in the density of rocks beneath the Earth's surface. The data collected are processed via standard methods to ensure the response recorded is that due only to the rocks in the ground. The results produce datasets that can be interpreted to reveal the geological structure of the sub-surface. The processed data is checked for quality by GA geophysicists to ensure that the final data released by GA are fit-for-purpose. This Complum Detailed Gravity Survey, NT (P199211) contains a total of 1565 point data values acquired at a spacing between 10 and 80 metres. The data is located in NT and were acquired in 1992, under project No. 199211 for None.
-
Gravity data measures small changes in gravity due to changes in the density of rocks beneath the Earth's surface. The data collected are processed via standard methods to ensure the response recorded is that due only to the rocks in the ground. The results produce datasets that can be interpreted to reveal the geological structure of the sub-surface. The processed data is checked for quality by GA geophysicists to ensure that the final data released by GA are fit-for-purpose. This Normandy G608 Detailed Gravity Survey, NT. (P199215) contains a total of 196 point data values acquired at a spacing between 500 and 1000 metres. The data is located in NT and were acquired in 1992, under project No. 199215 for None.
-
Gravity data measures small changes in gravity due to changes in the density of rocks beneath the Earth's surface. The data collected are processed via standard methods to ensure the response recorded is that due only to the rocks in the ground. The results produce datasets that can be interpreted to reveal the geological structure of the sub-surface. The processed data is checked for quality by GA geophysicists to ensure that the final data released by GA are fit-for-purpose. This Nobtrig Detailed Gravity Survey, NT (P199217) contains a total of 1255 point data values acquired at a spacing between 10 and 55 metres. The data is located in NT and were acquired in 1992, under project No. 199217 for None.
-
Gravity data measures small changes in gravity due to changes in the density of rocks beneath the Earth's surface. The data collected are processed via standard methods to ensure the response recorded is that due only to the rocks in the ground. The results produce datasets that can be interpreted to reveal the geological structure of the sub-surface. The processed data is checked for quality by GA geophysicists to ensure that the final data released by GA are fit-for-purpose. This Nobwest Detailed Gravity Survey, NT (P199218) contains a total of 408 point data values acquired at a spacing between 20 and 80 metres. The data is located in NT and were acquired in 1992, under project No. 199218 for None.
-
Gravity data measures small changes in gravity due to changes in the density of rocks beneath the Earth's surface. The data collected are processed via standard methods to ensure the response recorded is that due only to the rocks in the ground. The results produce datasets that can be interpreted to reveal the geological structure of the sub-surface. The processed data is checked for quality by GA geophysicists to ensure that the final data released by GA are fit-for-purpose. This Tennant Region Gravity Survey, NT (P199118) contains a total of 1402 point data values acquired at a spacing between 500 and 1000 metres. The data is located in NT and were acquired in 1991, under project No. 199118 for None.
-
Gravity data measures small changes in gravity due to changes in the density of rocks beneath the Earth's surface. The data collected are processed via standard methods to ensure the response recorded is that due only to the rocks in the ground. The results produce datasets that can be interpreted to reveal the geological structure of the sub-surface. The processed data is checked for quality by GA geophysicists to ensure that the final data released by GA are fit-for-purpose. This White Devil Detailed Gravity Survey, NT. (P199121) contains a total of 722 point data values acquired at a spacing between 25 and 100 metres. The data is located in NT and were acquired in 1991, under project No. 199121 for None.