TY - JOUR
T1 - Biogenicity of Spicular Geyserite from Te Kopia, New Zealand
T2 - Integrated Petrography, High-Resolution Hyperspectral and Elemental Analysis
AU - Murphy, Richard J.
AU - Van Kranendonk, Martin J.
AU - Baumgartner, Raphael
AU - Ryan, Chris
N1 - Funding Information:
R.J.M. acknowledges support from the University of Sydney. M.J.V.K. and R.B. acknowledge support from the UNSW, as well as from the Australian Research Council, through grant DP180103204. The authors are extremely grateful to the HySpex team at Norsk Elektro Optikk AS (Skedsmokorset, Norway) and Ivar Baarstad for doing the hyperspectral scanning of the sample.
Funding Information:
Australian Research Council (ARC) Discovery Project Grant DP180103204.
Publisher Copyright:
© Copyright 2021, Mary Ann Liebert, Inc., publishers 2021.
PY - 2021/1
Y1 - 2021/1
N2 - Hyperspectral and micro X-ray fluorescence (μXRF) imagery were used to derive maps of mineralogy and elemental chemistry from a sample of a siliceous hot spring deposit, or sinter, collected from a landslide breccia deposit at the base of the Paeroa fault, which bounds the eastern Taupo Rift at Te Kopia, Taupo Volcanic Zone, New Zealand. The sample is of a known biogenic sinter layer from a paleo-vent area of a recently extinct alkali chloride hot spring. The aim of the study was to distinguish it from other horizons derived from nonbiogenic sources, which is of relevance to early and extraterrestrial life research, specifically to help assess the potential reliability of morphology as an indicator of biology in the geological record. In particular, the distribution of opal, a common mineral in hot springs deposits that is known to preserve microbial features, and the relative abundances of Al-OH clay and water (OH and H2O) were mapped from hyperspectral imagery and element distributions defined by μXRF element mapping. Layers within the sinter sample composed of spicular geyserite - a type of micro-columnar stromatolite - showed contrasting mineralogy and water content in comparison with interspicular clastic sediment. Whereas clay was found to be concentrated in the interspicular sediment, high water contents characterized the spicules. μXRF imagery also showed differences in the composition of the two components of the spicule-bearing layers, with interspicular sediment being enriched in K, Ti, Fe, and Rb relative to the spicules, which are enriched in Ga. The contrasting nature of the mapped components highlights the detailed upward-branching nature of the spicules, identical to those found in living microstromatolites. These discriminants show that the spicular component can be discerned from the geological background through hyperspectral and μXRF mapping and used to define morphological features that may survive burial diagenesis and metamorphism as a biosignature in deep time rocks.
AB - Hyperspectral and micro X-ray fluorescence (μXRF) imagery were used to derive maps of mineralogy and elemental chemistry from a sample of a siliceous hot spring deposit, or sinter, collected from a landslide breccia deposit at the base of the Paeroa fault, which bounds the eastern Taupo Rift at Te Kopia, Taupo Volcanic Zone, New Zealand. The sample is of a known biogenic sinter layer from a paleo-vent area of a recently extinct alkali chloride hot spring. The aim of the study was to distinguish it from other horizons derived from nonbiogenic sources, which is of relevance to early and extraterrestrial life research, specifically to help assess the potential reliability of morphology as an indicator of biology in the geological record. In particular, the distribution of opal, a common mineral in hot springs deposits that is known to preserve microbial features, and the relative abundances of Al-OH clay and water (OH and H2O) were mapped from hyperspectral imagery and element distributions defined by μXRF element mapping. Layers within the sinter sample composed of spicular geyserite - a type of micro-columnar stromatolite - showed contrasting mineralogy and water content in comparison with interspicular clastic sediment. Whereas clay was found to be concentrated in the interspicular sediment, high water contents characterized the spicules. μXRF imagery also showed differences in the composition of the two components of the spicule-bearing layers, with interspicular sediment being enriched in K, Ti, Fe, and Rb relative to the spicules, which are enriched in Ga. The contrasting nature of the mapped components highlights the detailed upward-branching nature of the spicules, identical to those found in living microstromatolites. These discriminants show that the spicular component can be discerned from the geological background through hyperspectral and μXRF mapping and used to define morphological features that may survive burial diagenesis and metamorphism as a biosignature in deep time rocks.
KW - Biogenicity
KW - Hot springs
KW - Hyperspectral
KW - Spicular geyserite
KW - μXRF imagery.
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U2 - 10.1089/ast.2019.2067
DO - 10.1089/ast.2019.2067
M3 - Article
C2 - 33085533
AN - SCOPUS:85099129198
SN - 1531-1074
VL - 21
SP - 115
EP - 135
JO - Astrobiology
JF - Astrobiology
IS - 1
ER -