Pleistocene marine terraces in New Zealand: A review

An 11 m thick subhorizontal beach deposit rests on steeply dipping Cretaceous bedrock. Sediments, ranging from a basal boulder bed to upper sands, are poorly sorted and negatively skewed, indicating pronounced winnowing of fine material. Impact features on quartz grain surfaces attest to high-energy turbulent environments, and are similar to those found on clasts from modern nearby beaches. The Haast River was source to some of the sand and gravel. Heavy minerals from the Dun Mountain Ophiolite Belt were transported 85 km by fluvial/glacial and longshore drift processes, necessitating caution when using apparent lateral separation of source material for estimating strike-slip displacement rates on the Alpine Fault. An optical luminescence age estimate of 123 ± 7 ka for Knights Point beach sands dates to the last interglacial (MIS 5e). A shore-platform altitude of 113 m a.s.l. requires tectonic uplift of the Australian plate of 0.86 mm/yr, an order of magnitude less than the nearby Pacific plate.

Section: Uplift Ratesmentioning

confidence: 99%

Section: Synthesis Of Depositional Environmentmentioning

confidence: 99%

Section: Synthesis Of Depositional Environmentmentioning

confidence: 99%

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A tectonically uplifted marine shoreline deposit, Knights Point, Westland, New Zealand

Cooper¹,

Kostro

2006

“…All terrace heights quoted here are strandline heights, considered to represent the position of former shorelines (e.g., Pillans 1990). Heights were measured relative to mean high-tide level (tidal range 1.5-2 m), and are considered to be accurate to ±0.5 m.…”

Section: Marine Terracesmentioning

confidence: 99%

Holocene motion on the Akatore Fault, south Otago coast, New Zealand

Litchfield

Norris

2000

The Akatore Fault comprises the onshore leading edge of the Otago reverse fault-fold belt, part of the outboard zone of Australia-Pacific plate continental collision in the South Island. We examine stratigraphic and sedimentologic evidence of late Holocene reverse faulting along the Akatore Fault, and use radiocarbon dating to constrain fault rupture events and associated uplift of the Akatore fault block. Two fault rupture events are recorded in swamps on the downthrown, upstream side of the fault, as forest and/or peat horizons buried by silt, dated at post-3800 yr BP and 1150-1000 yr BP. The latest event coincides with the timing of uplift of a 3 m marine terrace on the coast, and the uplift of a second (6 m) is tentatively correlated to the penultimate event. The terrace height data, together with the amount of offset of alluvial gravels resting on the fluvial strath surface at the blocked swamp sites, suggests an average of 3 m of throw per uplift event. Distribution of throw along the fault suggests that the last event was not symmetrical about the centre of the scarp in the manner of the long-term throw. Offset of the third highest marine terrace, dated at 80 ka, can be wholly accounted for by the Holocene events, suggesting a period of quiescence between 80 000 and 3800 yr BP.

“…These facies are then interpreted in terms of the regional sedimentary controls operating on the Wanganui shelf. subsiding at a rate of c. 1 mm/yr, while uplift is occurring along the North Wanganui coast at c. 3-4 mm/yr (Pillans 1986(Pillans , 1990. Over the last 5 m.y., sedimentation on the central western shelf has been concentrated in the subsiding South Wanganui Basin, which, as a consequence, contains up to 4000 m of mainly Pliocene-Pleistocene terrigenous muds and sands deposited unconformably over eroded and faulted pre-Tertiary basement (Anderton 1981;Katz & Leask 1990).…”

Section: Introductionmentioning

confidence: 99%

Distribution and control of mixed terrigenous‐carbonate surficial sediment facies, Wanganui shelf, New Zealand

Gillespie

Nelson

1996

Shallow-marine, mixed temperate, terrigenouscarbonate sediments are accumulating on the shallow to deep Wanganui shelf (c. 20-110 m water depth). From cluster analysis of textural and compositional parameters, five surficial sediment facies and five subfacies have been defined for the shelf. Facies 1 (Bivalve-bearing [gravelly] sand), is a terrigenous-dominated, shallow shelf facies (<50 m), incorporating Subfacies la (Sand)-a modern felsic sand prism-and lb (Bivalve-bearing volcaniclastic gravelly sand)-modern to relict andesitic detritus and shell fragments. Facies 2 (Skeletal-dominated sandy gravel) comprises sediments containing >50% CaCO 3 , and occurs in the shallow to mid shelf region (c. 30-90 m) where levels of terrigenous input are reduced, and substrates and hydraulic conditions are favourable for carbonate production. Facies 2 comprises Subfacies 2a (Bivalve-dominated sandy gravel), 2b (Bryozoan/bivalve-dominated sandy gravel), and 2c (Bryozoan/bivalve-dominated muddy sandy gravel and gravelly muddy sand). Facies 2 sediments are