The graywackes of Paleozoic turbidite sequences of eastern Australia show a large variation in their trace element characteristics, which reflect distinct provenance types and tectonic settings for various suites. The tectonic settings recognised are oceanic island arc, continental island arc, active continental margin, and passive margins. Immobile trace elements, e.g. La, Ce, Nd, Th, Zr, Nb, Y, Sc and Co are very useful in tectonic setting discrimination. In general, there is a systematic increase in light rare earth elements (La, Ce, Nd), Th, Nb and the Ba/Sr, Rb/Sr, La/Y and Ni/Co ratios and a decrease in V, Sc and the Ba/Rb, K/Th and K/U ratios in graywackes from oceanic island arc to continental island arc to active continental margin to passive margin settings. On the basis of graywacke geochemistry, the optimum discrimination of the tectonic settings of sedimentary basins is achieved by La-Th, La-Th-Sc, Ti/Zr-La/Sc, La/Y-Sc/Cr, Th-Sc-Zr/10 and Th-Co-Zr/10 plots. The analysed oceanic island arc graywackes are characterised by extremely low abundances of La, Th, U, Zr, Nb; low Th/U and high La/Sc, La/Th, Ti/Zr, Zr/Th ratios. The studied graywackes of the continental island arc type setting are characterised by increased abundances of La, Th, U, Zr and Nb, and can be identified by the La-Th-Sc and La/Sc versus Ti/Zr plots. Active continental margin and passive margin graywackes are discriminated by the Th-Sc-Zr/10 and Th-Co-Zr/10 plots and associated parameters (e.g. Th/Zr, Th/Sc). The most important characteristic of the analysed passive margin type graywackes is the increased abundance of Zr, high Zr/Th and lower Ba, Rb, Sr and Ti/Zr ratio compared to the active continental margin graywackes.

Trace element characteristics of graywackes and tectonic setting discrimination of sedimentary basins

[1] Estimates of the average composition of various Precambrian shields and a variety of estimates of the average composition of upper continental crust show considerable disagreement for a number of trace elements, including Ti, Nb, Ta, Cs, Cr, Ni, V, and Co. For these elements and others that are carried predominantly in terrigenous sediment, rather than in solution (and ultimately into chemical sediment), during the erosion of continents the La/element ratio is relatively uniform in clastic sediments. Since the average rare earth element (REE) pattern of terrigenous sediment is widely accepted to reflect the upper continental crust, such correlations provide robust estimates of upper crustal abundances for these trace elements directly from the sedimentary data. Suggested revisions to the upper crustal abundances of Taylor and McLennan [1985] are as follows (all in parts per million): Sc = 13.6, Ti = 4100, V = 107, Cr = 83, Co = 17, Ni = 44, Nb = 12, Cs = 4.6, Ta = 1.0, and Pb = 17. The upper crustal abundances of Rb, Zr, Ba, Hf, and Th were also directly reevaluated and K, U, and Rb indirectly evaluated (by assuming Th/U, K/U, and K/Rb ratios), and no revisions are warranted for these elements. In the models of crustal composition proposed by Taylor and McLennan [1985] the lower continental crust (75% of the entire crust) is determined by subtraction of the upper crust (25%) from a model composition for the bulk crust, and accordingly, these changes also necessitate revisions to lower crustal abundances for these elements.

https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2000GC000109

Relationships between the trace element composition of sedimentary rocks and upper continental crust

Provenance signatures of sandstone-mudstone suites determined using discriminant function analysis of major-element data

https://sites.williams.edu/rcox/files/2013/01/MudrockChem.pdf

The influence of sediment recycling and basement composition on evolution of mudrock chemistry in the southwestern United States

Geochemical and NdSr isotopic composition of deep-sea turbidites: Crustal evolution and plate tectonic associations

Sedimentary geology: An introduction to sedimentary rocks and stratigraphy

Two major marine surveys off northern Papua New Guinea (PNG) earlier this year now suggest, when survivors' reports are taken into account, that last summer's disastrous tsunami there was caused by a sediment slump 25 km offshore. The slump was probably the result of seabed shaking from an earthquake. Not only was a sediment slump, or submarine landslide, responsible for the tsunami, according to the data, but the magnitude and wave-height distribution of the tsunami along the coast were the result of focusing by local seabed morphology.

The conclusions are based on new off-shore bathymetry, remote operated vehicle (ROV) dive investigations, the time delay between the source earthquake and when the tsunami struck, computer simulation models, and earthquake aftershock distribution. The most critical evidence is in survivors' accounts of the timing of the tsunami relative to the initially felt earthquake and aftershock [see Davies, 1998a].

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/99EO00241

Sediment slump likely caused 1998 Papua New Guinea tsunami

Between December 6, 1985, and January 9, 1986, the Hawaii Institute of Geophysics Research Vessel Moana Wave surveyed the Manus Basin, north of New Britain, Papua New Guinea. This basin occupies a back-arc position with respect to the New Britain arc-trench system and contains an active plate boundary (Figure 1; also Taylor [1979]). Organized under the aegis of the Committee for Coordination of Joint Prospecting for Mineral Resources in South Pacific Offshore Areas (CCOP/SOPAC), the cruise was part of a program to assess the mineral potential of southwest Pacific marginal basins and included a National Science Foundation-sponsored study of crustal accretion processes in a fastspreading (greater than 100 mm/yr) back-arc basin. The tectonic fabric of the Manus Basin was mapped and defined with the Sea MARC II sidescan sonar and bathymetric mapping system. Then dredge samples and cores were collected, and a towed bottom camera system was used to search for signs of hydrothermal activity.

Keith A.W. Crook

Papers

Trace element characteristics of graywackes and tectonic setting discrimination of sedimentary basins

Sedimentary geology: An introduction to sedimentary rocks and stratigraphy

Sediment slump likely caused 1998 Papua New Guinea tsunami

Hydrothermal chimneys and associated fauna in the Manus Back‐Arc Basin, Papua New Guinea

Depositional processes along a very low-gradient, suspended-load stream: the Barwon River, New South Wales