Michael G. Lawrence

University of Queensland , Brisbane, Queensland, Australia

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Publications (24)29.11 Total impact

  • 01/2011;
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    ABSTRACT: Mangroves grow along coastal lines over a wide latitudinal range and therefore have great potential for recording high-resolution environmental information of tropical to sub-tropical regions. Such records can potentially be linked to tropical corals and temperate tree rings. We undertook carbon isotope, trace element and lead isotope analyses on a sample of a living mangrove (Rhizophora apiculata) of known age from Leizhou Peninsula (about 20ºN, 109-110ºE) from the northern coast of the South China Sea. The results show that the tree-rings are annual and their alpha-cellulose d13C values are significantly correlated with ring width, annual sea level, salinity and sea surface temperatures in the growth period, suggesting mangrove tree-rings may be used to characterize past sea level fluctuations (Yu et al, 2004, Geophysical Research Letters, 31, L11203, doi:10.1029/2004GL019450). The concentrations of most trace elements show weak declining trends from 1982 to 1999, punctuated by several high concentration spikes. The declining trends are positively correlated with ring width and negatively correlated with water use efficiency inferred from alpha-cellulose delta13C, suggesting a physiological control over metal-uptake in this species. The episodic metal concentration-peaks cannot be interpreted with lateral movement in the tree trunk or growth activities, and appear to be related to local environmental pollution events. Lead isotope compositions clearly document the importance of gasoline Pb as an atmospheric contaminant taken up by tree leaves. Moreover, shale-normalised rare earth element and yttrium (REE+Y) patterns are relatively flat and consistent across the growth period, with all patterns showing a positive Ce anomaly and elevated Y/Ho ratio. The positive Ce anomaly is observed regardless of the choice of normaliser, in contrast to previously reported REE patterns for terrestrial and marine plants (Yu et al. 2007, Nuclear Instruments & Methods in Physics Research-B, doi: 10.1016/j.nimb. 11.127). This study demonstrates the promising potential for the use of mangroves for monitoring environmental change.
    01/2011;
  • Y Zhou, J. X. Zhao, Y Zhu, Y Feng, M. G. Lawrence, Q. Chi, J Yan, Q Zhou
    01/2011;
  • 01/2011;
  • Ke-Fu Yu, Jian-xin Zhao, Michael G. Lawrence, Yuexing Feng
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    ABSTRACT: Growth hiatuses in massive corals are usually indicative of past ecological or environmental stresses. Among 37 fossil Porites colonies surveyed from the reef flat of Dadonghai fringing reef at Sanya, Hainan Island, northern South China Sea, seven of them were found to show clear evidence of past mortality, representing a population of -19%. Among these samples, two of them (SYO-13 and SYO-28) display clear growth hiatuses reflecting mortality followed by subsequent recruitment, and five others exhibit a well-preserved mortality surface and no subsequent recruitment. The growth hiatuses were dated using high-precision thermal ionisation mass spectrometry U-series techniques. The age results suggest all the dated corals formed and died in the mid Holocene. Multiple dates below the growth hiatuses suggest that SYO-13 and SYO-28 died at 6298--11 and 6929--19 a BP (i.e. years before AD 1950), respectively. Multiple dates above the growth hiatuses indicate that growth in SYO-13 and SYO-28 resumed at 6257--14 and 6898--20 a BP, respectively. The calculated durations of growth hiatuses are therefore 41--18 a for SYO-13 and 31--28 a for SYO-28, respectively, implying growth resumed within decades after the mortality events. U-series dating of four other samples with dead heads suggests that they died at 6035--53, 6059--23, 6127--22 and 6474--24 a BP, respectively. In addition, using solution inductively coupled plasma mass spectrometry (ICP-MS), monthly resolution Sr/Ca and Mg/Ca ratios were determined for the annual growth bands below and above the growth hiatuses for three of the dated samples. The Sr/Ca and Mg/Ca profiles indicate that the three corals probably died in different seasons (from spring to autumn), and the mortality appears to be unrelated to anomalous sea surface temperature-induced bleaching. 2010 John Wiley & Sons, Ltd.
    Journal of Quaternary Science 12/2010; 25(8):1284-1292. · 2.94 Impact Factor
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    ABSTRACT: White pottery is among the most significant finds from China's earliest state, Erlitou (c. 1900–1500 bc). Samples were primarily discovered in small numbers from elite tombs of a few sites, leading to the hypothesis that they were made at only a few locations and then circulated regionally as prestige items. To facilitate determining provenances, we compare the ICP–MS trace elements and TIMS Sr isotopes of whiteware with two soil samples from Nanwa, a possible manufacturing site, and with shards found at three other sites: Erlitou, Huizui and Nanzhai. The Nanwa shards demonstrate special elemental and Sr isotopic features. Considering the chemical observation and archaeological background together, we propose that Nanwa was a centre for whiteware production, although the two soil samples we collected there were probably not the exact materials used. Some whiteware pieces from Erlitou, Huizui and Nanzhai fall in the chemical field defined by Nanwa samples, indicating that they were possibly made at Nanwa. Many other samples from these three sites plot outside the Nanwa field, implying they were probably not Nanwa products. This study demonstrates that while chemical sourcing is very useful, firm archaeological context must remain the cornerstone of such research.
    Archaeometry 08/2010; 52(5):760 - 776. · 1.29 Impact Factor
  • Quaternary Research 01/2008; · 2.20 Impact Factor
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    ABSTRACT: Late Permian coals and coal measures in the Bowen Basin, Australia, are extensively mineralised with carbonates as cleat fillings and veins. The calcites in coal samples exhibit large variations in rare-earth element (REE) patterns and Sm-Nd ratios with some superchondritic values. Samples enriched in heavy REE (HREE) relative to light REE (LREE) define an Sm-Nd isochron corresponding to an age of 235 +/- 15 Ma, which is consistent with the timing of final contractional phase of the Hunter-Bowen orogeny. The corresponding initial epsilon Nd is + 1.2 combined with HREE-enriched patterns suggests significant fluid interaction with primitive source rocks, which are consistent with arc-related volcanogenic sediments in the basin. Calcites characterised by HREE depletion relative to LREE are not in Sm-Nd isotopic equilibrium with the former samples that is interpreted to be due to the effect of a later hydrothermal event during the Late Triassic-Early Jurassic. Vein calcites in mudrocks from the coal measures display more pronounced HREE depletion and significant positive EuCN anomalies, which is related to the later hydrothermal event. REE distributions, together with the basin burial history, suggest that physico-chemical environments of fluid-flow events during the two separate major tectonic regimes were significantly different. This study shows that a combined application of Sm-Nd dating and REE geochemical tracing of authigenic carbonate minerals is very useful to constrain the evolution of multiple fluid-flow events in a sedimentary basin with a complex history. (c) 2006 Elsevier B.V All rights reserved.
    Chemical Geology 03/2007; 238(1-2):63-71. · 3.15 Impact Factor
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    ABSTRACT: Annual variations from 1982 to 1999 of a wide range of trace elements and reconnaissance Pb isotopes (Pb-207/Pb-206 and Pb-208/Pb-206) were analyzed by solution ICP-MS on digested ash from mangrove Rhizophora apiculata, obtained from Leizhou Peninsula, along northern coast of South China Sea. The concentrations of the majority of elements show a weak, declining trend with growth from 1982 to 1999, punctuated by several high concentration spikes. The declining trends are positively correlated with ring width and negatively correlated with inferred water-use efficiency, suggesting a physiological control over metal-uptake in this species. The episodic metal concentration-peaks cannot be interpreted with lateral movement or growth activities and appear to be related to environmental pollution events. Pb isotope ratios for most samples plot along the 'Chinese Pb line' and clearly document the importance of gasoline Pb as a source of contaminant. Shale-normalised REE + Y patterns are relatively flat and consistent across the growth period, with all patterns showing a positive Cc anomaly and elevated Y/Ho ratio. The positive Ce anomaly is observed regardless of the choice of normaliser, in contrast to previously reported REE patterns for terrestrial and marine plants. This pilot study of trace element, REE + Y and Pb isotope distribution in mangrove tree rings indicates the potential use of mangroves as monitors of historical environmental change. (c) 2006 Elsevier B.V. All rights reserved.
    Nuclear Instruments and Methods in Physics Research Section B Beam Interactions with Materials and Atoms 02/2007; 255(2):399-408. · 1.27 Impact Factor
  • Michael G. Lawrence, Balz S. Kamber
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    ABSTRACT: The rare earth element and yttrium concentrations of the NRCC reference materials North Atlantic Surface seawater, NASS-5; Coastal Atlantic Surface Seawater, CASS-4; and the estuarine water, SLEW-3 have been precisely determined by ICP-MS after ca. 1:8 preconcentration following a triple chelation using HDEHP (phosphoric acid 2-ethylhexyl ester - mono and di ester mixture) in heptane, and back extraction in nitric acid. We propose reference values with uncertainties for all naturally occurring lanthanides and yttrium.
    Geostandards Newsletter-the Journal of Geostandards and Geoanalysis - GEOSTAND NEWSLETT-J GEOSTAND. 01/2007; 31(2):95-103.
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    Michael G. Lawrence, Balz S. Kamber
    Marine Chemistry - MAR CHEM. 01/2007; 105(1):181-181.
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    ABSTRACT: We present a method to constrain the timing of fissure generation related to late Quaternary seismic events using the uranium-series technique. Dated samples were from travertine deposits precipitated in co-seismic extensional fissures along major active faults in Western Turkey. Stable isotope and REE data indicate that the precipitation of the fissure travertines was not controlled by the hydrologic regime that is responsible for the speolethem deposition in the same region. Moreover, the REE composition and concentration of the water from which the fissure travertine precipitated were significantly different from those of the current geothermal waters in the study area. The carbonate generation in the co-seismic fissures is interpreted to be the product of rapid precipitation from deeply infiltrated and CO2-enriched surface water during seismic strain cycles. Results show that U-series dating of fracture-filling travertine deposits from seismically active areas provide important temporal information relevant to establishing recurrence intervals of late Quaternary and prehistoric major earthquake events. Precise dating of prehistoric earthquakes may be of great value for seismic hazard studies and earthquake forecasting research, for which accurate estimates of recurrence intervals are critical.
    Earth and Planetary Science Letters 01/2007; 257:450-462. · 4.35 Impact Factor
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    Michael G. Lawrence, Stacy D. Jupiter, Balz S. Kamber
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    ABSTRACT: The rare earth elements are strong provenance indicators in geological materials, yet the potential for tracing provinciality in surface freshwater samples has not been adequately tested. Rare earth element and yttrium concentrations were measured at 33 locations in the Pioneer River catchment, Mackay, central Queensland, Australia. The rare earth element patterns were compared on the basis of geological, topographical and land-use features in order to investigate the provenancing potential of these elements in a small freshwater system. The rare earth element patterns of streams draining single lithological units with minor land modification show strongly coherent normalised behaviour, with a loss of coherence in agricultural locations. Evidence is reported for an anthropogenic Gd anomaly that may provide a useful hydrological tracer in this region since the introduction of magnetic resonance imaging in 2003. Several samples display a superchondritic Y/Ho mass ratio (up to 44), which is not explainable within the constraints imposed by local geology. Instead, it is suggested that the additional Y is derived from a marine source, specifically marine phosphorites, which are a typical source of fertiliser phosphorus. The data indicate that, under some circumstances, scaled and normalised freshwater rare earth patterns behave conservatively.
    Marine and Freshwater Research 09/2006; 57:725-736. · 1.98 Impact Factor
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    ABSTRACT: We present data for the rare earth elements and yttrium (REY) in the National Research Council of Canada natural river water reference material SLRS-4 and 19 natural river waters from small catchments in South-East Queensland, Australia, by a direct ICP-MS method. The 0.22μm filtered river water samples show a large degree of variability in both the REY concentration, e.g., La varies from 13 to 1157ppt, and shape of the alluvial-sediment-normalised REY patterns with different samples displaying light, middle or heavy rare earth enrichment. In addition, a spatial study was undertaken along the freshwater section of Beerburrum Creek, which demonstrates that ~75% of the total REYs in this waterway are removed prior to estuarine mixing without evidence of fractionation.
    Aquatic Geochemistry 01/2006; 12(1):39-72. · 1.53 Impact Factor
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    ABSTRACT: A direct quadrupole ICP-MS technique has been developed for the analysis of the rare earth elements and yttrium in natural waters. The method has been validated by comparison of the results obtained for the river water reference material SLRS-4 with literature values. The detection limit of the technique was investigated by analysis of serial dilutions of SLRS-4 and revealed that single elements can be quantified at single-digit fg/g concentrations. A coherent normalised rare earth pattern was retained at concentrations two orders of magnitude below natural concentrations for SLRS-4, demonstrating the excellent inter-element accuracy and precision of the method. The technique was applied to the analysis of a diluted mid-salinity estuarine sample, which also displayed a coherent normalised rare earth element pattern, yielding the expected distinctive marine characteristics. (c) 2006 Published by Elsevier Ltd.
    01/2006;
  • M. G. Lawrence, K. D. Collerson, B. S. Kamber
    Geochmica et Cosmochimica Acta 01/2006;
  • Michael G. Lawrence, Balz S. Kamber
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    ABSTRACT: Complete rare earth element (except Eu) and Y concentrations from the estuarine mixing zone (salinity = 0.2 to 33) of Elimbah Creek, Queensland, Australia, were measured by quadrupole ICP-MS without preconcentration. High sampling density in the low salinity regime along with high quality data allow accurate tracing of the development of the typical marine rare earth element anomalies as well as Y/Ho fractionation.Over the entire estuary, the rare earth elements are strongly removed relative to a freshwater endmember (60–80% removal). This large overall removal occurs despite a strong remineralisation peak (190% for La, 130% for Y relative to the freshwater endmember) in the mid-salinity zone. Removal and remineralisation are accompanied by fractionation of the original (freshwater) rare earth element pattern, resulting in light rare earth element depletion. Estuarine fractionation generates a large positive La anomaly and a superchondritic Y/Ho ratio. Conversely, we observe no evidence to support the generation of the negative Ce anomaly in the estuary.With the exception of Ce, the typical marine rare earth element features can thus be attributed to estuarine mixing processes. The persistence of these features in hydrogenous sediments for at least 3.71 Ga highlights the importance of estuarine processes for marine chemistry on geological timescales.
    Marine Chemistry. 01/2006;
  • Edraki M, Golding SD, Baublys KA, Lawrence MG
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    ABSTRACT: Mineralogical, hydrochemical and S isotope data were used to constrain hydrogeochemical processes that produce acid mine drainage from sulfidic waste at the historic Mount Morgan Au-Cu mine, and the factors controlling the concentration of SO4 and environmentally hazardous metals in the nearby Dee River in Queensland, Australia. Some highly contaminated acid waters, with metal contents up to hundreds of orders of magnitude greater than the Australia-New Zealand environmental standards, by-pass the water management system at the site and drain into the adjacent Dee River. Mine drainage precipitates at Mt. Morgan were classified into 4 major groups and were identified as hydrous sulfates and hydroxides of Fe and Al with various contents of other metals. These minerals contain adsorbed or mineralogically bound metals that are released into the water system after rainfall events. Sulfate in open pit water and collection sumps generally has a narrow range of S isotope compositions (delta(34)S = 1.8-3.7 parts per thousand) that is comparable to the orebody sulfides and makes S isotopes useful for tracing SO4 back to its source. The higher delta(34)S values for No. 2 Mill Diesel sump may be attributed to a difference in the source. Dissolved SO4 in the river above the mine influence and 20 km downstream show distinctive heavier isotope compositions (delta(34)S = 5.4-6.8 parts per thousand). The Dee River downstream of the mine is enriched in S-34 (delta(34)S = 2.8-5.4 parts per thousand) compared with mine drainage possibly as a result of bacterial SO4 reduction in the weir pools, and in the water bodies within the river channel. The SO4 and metals attenuate downstream by a combination of dilution with the receiving waters, SO4 reduction, and the precipitation of Fe and Al sulfates and hydroxides. It is suggested here that in subtropical Queensland, with distinct wet and dry seasons, temporary reducing environments in the river play an important role in S isotope systematics.
    Applied Geochemistry 05/2005; 20(4):789-805. · 1.71 Impact Factor
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    ABSTRACT: Cited By (since 1996): 23, Export Date: 18 June 2012, Source: Scopus
    Earth and Planetary Science Letters 10/2004; 227(1-2):135-154. · 4.35 Impact Factor
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    ABSTRACT: A new influx of sea-rafted pumice reached the eastern coast of Australia in October 2002, approximately 1 year after a felsic, shallow-marine explosive eruption at a previously unknown volcano (0403-091) along the Tofua volcanic arc (Tonga). The eruption produced floating pumice rafts that first became stranded in Fiji in November 2001, approximately 1 month after the eruption. Strandings of sea-rafted pumice along shorelines have been the only record of products from this submarine explosive eruption at the remote, submerged volcano. Computed drift trajectories of the sea-rafted pumice using numerical models of southwest Pacific surface wind fields and ocean currents indicate two cyclonic systems disturbed the drift of pumice to eastern Australia, as well as the importance of the combined wave and direct wind effect on pumice trajectory. Pumice became stranded along at least two-thirds (N2000 km) of the coastline of eastern Australia, being deposited on beaches during a sustained period of fresh onshore winds. Typical amounts of pumice initially stranded on beaches were 500–4000 individual clasts per m 2 , and a minimum volume estimate of pumice that arrived to eastern Australia is 1.25Â10 5 m 3 . Pumice was beached below maximum tidal/storm surge levels and was quickly reworked back into the ocean, such that the concentration of beached pumice rapidly dissipated within weeks of the initial stranding, and little record of this stranding event now exists. Most stranded pumice clasts ranged in size from 2 to 5 cm in diameter; the largest measured clasts were 10 cm in Australia and 20 cm in Fiji. The pumice has a low phenocryst content (b5% modal), containing the assemblage of calcic plagioclase (An 88À74), augite (En 35 Fs 29 Wo 36), pigeonite (En 45 Fs 46 Wo 9), and titanomagnetite. Examined pumice clasts are 0012-821X/$ -see front matter D 2004 Elsevier B.V. All rights reserved.
    Earth and Planetary Science Letters 01/2004; 227(doi: 10.1016/j.epsl.2004.08.009):135-154. · 4.35 Impact Factor