ALBERT — All Library Books, journals and Electronic Records Telegrafenberg

1

Unknown

Age determination of sediment core V14 in the Tai O Bay (Table 1)

Bahr, André ; Wong, H K ; Yim, Wyss W-S ; [et al.]

PANGAEA

In: Supplement to: Bahr, André; Wong, H K; Yim, Wyss W-S; Huang, G; Lüdmann, Thomas; Chan, L S; Ridley Thomas, W N (2005): Stratigraphy of Quaternary inner-shelf sediments in Tai O Bay, Hong Kong, based on ground-truthed seismic profiles. Geo-Marine Letters, 25(1), 20-33, https://doi.org/10.1007/s00367-004-0185-y

add to mindlist on the mindlist

Details

Publication Date: 2023-05-12

Description: High-resolution boomer profiles from Tai O Bay, Hong Kong SAR, were ground-truthed using ten discontinuously sampled boreholes penetrating bedrock with a maximum length of 82.1 m. The relationship between depth below seabed and seismic profiles was established through the measurement of two borehole compressional-wave velocity profiles. In departure from previous interpretations, nine Quaternary seismic units were identified, which can be divided into eight systems tracts formed by cycles of fourth-order sea-level fluctuations dating back at least to marine isotope stage (MIS) 7 (ca. 190-245 ka). These consist of two lowstand systems tracts, two transgressive systems tracts, and four highstand systems tracts. Secondary unconformities within the highstand deposits are interpreted to document fifth-order sea-level fluctuations. Lowstand deposits are less common because, as soon as the sea level drops by a few metres, Tai O Bay becomes sub-aerially exposed, leading to widespread non-deposition or erosion. At the same time, extensive fluvial erosion and channel incision take place. Filling of the fluvial channels occurs during rising sea level. Lowstand sediments (if present) are generally landslide deposits laid down on a basal alluvial plain. Uncorrected accelerator mass spectrometry (AMS) radiocarbon dates of mollusc shells show that the depositional environment was marine since 6.2 ka, becoming gradually more brackish as a result of progradation of the Pearl River delta. The computed average sedimentation rate for the period 6.2-4.1 ka is 4.4 m/1,000 year, and approximately 1 m/1,000 year since 4.1 ka.

Keywords: Age, 14C AMS; Age, dated; Age, dated, error to older; Age, dated, error to younger; Age, dated material; Depth, bottom/max; DEPTH, sediment/rock; Depth, top/min; Sample code/label; Tai_O_Bay_V14; VC; Vibro corer; δ13C, skeletal carbonate; δ13C, standard deviation

Type: Dataset

Format: text/tab-separated-values, 70 data points

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

DATA PANGAEA

S·F·X

Fulltext

2

Electronic Resource

Correlation between magnetic susceptibility and distribution of heavy metals in contaminated sea-floor sediments of Hong Kong Harbour (1998)

Chan, L. S. ; Yeung, C. H. ; Yim, W. W.-S. ; [et al.]

Springer

Environmental geology 36 (1998), S. 77-86

add to mindlist on the mindlist

Details

ISSN: 1432-0495

Keywords: Key words Magnetic susceptibility ; Sea-floor sediments ; Heavy metals ; Hong Kong

Source: Springer Online Journal Archives 1860-2000

Topics: Geosciences

Notes: Abstract Magnetic susceptibility measurements were conducted on 24 vibrocores obtained from an area located off the northeastern coast of Lantau Island in Hong Kong. High intensities of magnetic susceptibility were detected in the uppermost sections of the majority of the cores. Several magnetic parameters measured for one of the cores suggest that the variations in the magnetic characteristics over depth are mainly due to varying concentrations of the magnetic minerals. Since a strong correlation has been found between magnetic susceptibility and the heavy metals Pb, Cu, Zn and Cr, an anthropogenic contamination origin is thought to be the cause. The present study shows that magnetic susceptibility is a fast, inexpensive and non-destructive method for the detection and mapping of contaminated sediments.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/s002540050322

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

3

Electronic Resource

Global Seismic Hazard Assessment Based on Area Source Model and Seismicity Data (1998)

CHEN, Y. ; Liu, J. ; Chen, L. ; [et al.]

Springer

Natural hazards 17 (1998), S. 251-267

add to mindlist on the mindlist

Details

ISSN: 1573-0840

Keywords: global seismic hazard ; area source model ; seismicity parameter ; Kernel function

Source: Springer Online Journal Archives 1860-2000

Topics: Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences

Notes: Abstract A global seismic hazard assessment was conducted using the probabilistic approach in conjunction with a modified means of evaluating the seismicity parameters. The earthquake occurrence rate function was formulated for area source cells from recent instrumental earthquake catalogs. For the statistical application of the G–R relation of each source cell, the upper- and lower-bound magnitudes were determined from, respectively, historical earthquake data using a Kernel smoothing operator and detection thresholds of recent catalogs. The seismic hazard at a particular site was obtained by integrating the hazard contribution from influencing cells, and the results were combined with the Poisson distribution to obtain the seismic hazard in terms of the intensity at 10% probability of exceedance for the next 50 years. The seismic hazard maps for three countries, constructed using the same method, agree well with the existing maps obtained by different methods. The method is applicable to both oceanic and continental regions, and for any specific duration of time. It can be used for those regions without detailed geological information or where the relation between existing faults and earthquake occurrence is not clear.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1023/A:1008094016624

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

4

Unknown

Flower-like apatite recording microbial processes through deep geological time and its implication to the search for mineral records of life on Mars (2014)

Sun, S., Chan, L. S., Li, Y.-L.

Mineralogical Society of America

In: American Mineralogist

add to mindlist on the mindlist

Details

Publication Date: 2014-10-02

Description: The biological cycling of phosphorus on Earth could be as early as the origin of life in early Archean. However, because of the low abundance and fine particle size, phosphate related to microbial ecophysiological activities in early sedimentary rocks, especially those deposited before the Great Oxidation Event (GOE, ca. 2.45–2.32 Ma), is still poorly addressed. It is not until recently that certain petrographic and mineralogical features of apatite in the early Precambrian sedimentary rocks were found related to microbial activities. In this study, we report high-resolution electron microscopic investigations on apatite from the Neoarchean to early Paleoproterozoic banded iron formations (BIFs), Mesoproterozoic to Lower Cambrian black shale and phosphorites, and Pliocene sediments. Apatite in BIFs occurs as 4–8 μm radial flowers with "petals" made of apatite rods. Their mineralogical and petrologic features are highly similar to those in the younger sedimentary rocks in which biomass have been confirmed to play an important role in the mineralization of phosphate. We suggest that these sedimentary rocks or sediments have experienced similar phosphogenetic processes mediated by biomass that led to the mineralization of phosphorus. The formation and preservation of phosphate (apatite) with conspicuous recognizable features in association with biological activities from Late Archean to Pliocene implies its universal significance in recording microbial processes through deep geological evolution. With mild dynamic processes, the martian (sub)surface has better preservation conditions than Earth, and the micro-structure of phosphate formed in environments mediated by microorganisms could be recognized by high-resolution observations on the surface of Mars or returned samples, if microbial life ever developed on Mars.

Print ISSN: 0003-004X

Electronic ISSN: 1945-3027

Topics: Geosciences

Published by Mineralogical Society of America

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

PAPER CURRENT

S·F·X

Fulltext

5

Unknown

Tracking the evolution of Late Mesozoic arc-related magmatic systems in Hong Kong using in-situ U-Pb dating and trace element analyses in zircon (2017)

Tang, D. L. K., Wilson, C. J. N., Sewell, R. J., Seward, D., Chan, L. S., Ireland, T. R., Wooden, J. L.

Mineralogical Society of America

In: American Mineralogist

add to mindlist on the mindlist

Details

Publication Date: 2017-11-02

Description: The links between large-scale silicic volcanism and plutonism offer insights into the dynamics of crustal magmatic systems and growth of continental crust. In Hong Kong, voluminous silicic ignimbrites and linked plutons record a ~26 Myr period of magmatism from ~164 to 138 Ma. We present data from these linked volcanic-plutonic assemblages at the Lantau and High Island caldera complexes, with an emphasis on the ~143–138 Ma activity from the latter. To track the evolution of these magmatic systems, U-Pb dating and trace element analyses using secondary-ion mass spectrometry (SIMS) were carried out on zircons from 21 samples from both volcanic and plutonic samples. The SIMS age data sets divide into two groups across volcanic and plutonic origins: (1) seven samples with unimodal age spectra [five of which have the same mean value as the published Isotope Dilution Thermal Ionization Mass Spectrometry (ID-TIMS) age from the same sample]; and (2) 14 samples yielding multiple age components. Age patterns from both groups suggest that the previously separated ~143 Ma Repulse Bay (RBVG) and ~141–140 Ma Kau Sai Chau volcanic groups (KSCVG) instead represent activities over a single ~5 Myr period. Direct linkages previously proposed between some volcanic and plutonic units for this period (e.g., High Island Tuff, Kowloon Granite) are no longer supported, and magmatism represented by exposed plutons continued until 137.8 ± 0.8 Ma (Mount Butler Granite). Under CL imagery, a wide range of zircon textures identified in both volcanic and plutonic samples is indicative of complex processes, some of which are identified through trace element data coupled with textural characteristics. Overall, intra-grain (cores vs. rims; sector-zonation) and intra-sample variations in trace element abundances and ratios are larger than those between samples. Zircon chemistries in both volcanic and plutonic samples fall into two groups during the ~5 Myr history of the High Island caldera magmatic system. One group (RBVG and "cold" granites) includes inherited grains back to 164 Ma and wider ranges in Hf, Y, total trivalent elements, Th and U concentrations and Th/U, Yb/Gd, and U/Yb ratios than the other (KSCVG and "hot" granites). Two possible evolutionary models of the High Island caldera magmatic system are: (1) the system randomly tapped a single crustal domain that fluctuated in temperature as a result of varying interactions of hotter melts, or (2) the volcanic and plutonic records reflect the interplay of two crustal domains with contrasting "low-" and "high-temperature" characteristics. In Hong Kong, some plutonic bodies were comagmatic with large-scale volcanism, while others were emplaced at shallow crustal levels independently of volcanism, matching the current two end-member views of the volcanic-plutonic relationship.

Print ISSN: 0003-004X

Electronic ISSN: 1945-3027

Topics: Geosciences

Published by Mineralogical Society of America

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

PAPER CURRENT

S·F·X

Fulltext

6

Unknown

Quartz nanocrystals in the 2.48 Ga Dales Gorge banded iron formation of Hamersley, Western Australia: Evidence for a change from submarine to subaerial volcanism at the end of the Archean (2013)

Li, Y.-L., Cole, D. R., Konhauser, K., Chan, L. S.

Mineralogical Society of America

In: American Mineralogist

add to mindlist on the mindlist

Details

Publication Date: 2013-03-30

Description: Banded iron formations (BIF) have recently been used as proxies for tracking the chemical changes associated with the transition from an anoxic to oxic atmosphere around 2.45 billion years ago, known as the Great Oxidation Event (GOE). The timing of the GOE has been ascribed to both the collapse of a methane greenhouse and a decreased overall demand for oxygen due to the production of more oxidizing gases associated with greater subaerial volcanism. The latter is a byproduct of a period of high mantle plume activity and the formation of new continental crust between 2.51 to 2.45 Ga. Here we report unique mineral evidence for momentary subaerial volcanism recorded in hematite-rich layers of the 2.48 Ga BIF from Dales Gorge, Hamersley of Western Australia. The BIF contains euhedral quartz nanocrystals (QNC), which only occur on the surfaces or in cavities of hematite breccias exhibiting soft-sediment features and an exogenous source. These QNCs with an average size of 170–100 nm are distinct to the amorphous chert in the BIF mineral assemblage and have the smallest crystal sizes of well-crystallized quartz ever reported. We suggest that QNCs represent pyroclastic materials that were transported as dust particles to the BIF depositional setting. Although the analysis of one specific BIF unit does not provide proof of changing modes of volcanism during the Archean-Paleoproterozic transition, this high-resolution petrological study does confirm that subaerial volcanism existed at that time.

Print ISSN: 0003-004X

Electronic ISSN: 1945-3027

Topics: Geosciences

Published by Mineralogical Society of America

Permalink