Age constraints on surface deformation recorded by fossil shorelines at Cape Range, Western Australia

2020 ◽  
Author(s):  
Michael R. Sandstrom ◽  
Michael J. O’Leary ◽  
Milo Barham ◽  
Yue Cai ◽  
E. Troy Rasbury ◽  
...  
Keyword(s):  
Sea Level ◽  
Western Australia ◽  
Late Miocene ◽  
Surface Deformation ◽  
Vertical Displacement ◽  
Relative Deformation ◽  
Last Interglacial ◽  
Data Set ◽  
Oxygen Isotope Stage ◽  
Strontium Isotope Stratigraphy

Laterally continuous terraces along the western flank of Cape Range, Western Australia, record both past sea-level highstands and postdepositional vertical displacement. Four distinct fossil coral reef terraces extend nearly the entire length of the slowly uplifting anticlinal structure (∼100 km), enabling documentation of the timing and degree of deformation-induced elevation contamination of past sea-level estimates from fossil shorelines. Here, we present detailed elevations of the four terraces using differential global positioning system (DGPS) and airborne light detection and ranging (LiDAR) data sets, along with new ages for the three upper terraces. Geochemical dating using strontium isotope stratigraphy techniques revealed, from highest to lowest elevation: a late Miocene reef terrace, a late Pliocene shoreline, and a prominent mid-Pleistocene reef terrace (probably associated with the marine oxygen isotope stage 33−31 interglacial), along with a broad last interglacial (Eemian) reef terrace and lagoon, which terminate at the modern shoreline. Laterally variable elevation data integrated with newly defined ages for the terraces demonstrate a gradual and continuous relative deformation in the region that spans at least the last 6.5 m.y. and constrains the emergence of the Cape Range to sometime prior to the late Miocene. This data set also shows that the most recent interglacial shoreline has undergone <1.3 m of vertical warping, suggesting minimal deformation since deposition. By tracing relative uplift rates over multiple terraces for ∼100 km of coastline, we placed constraints on maximum relative sea level (RSL) for the older terraces. Most notably, we were able to place strict maximum RSL elevations of <+34 m on the Pliocene terrace and <+16.5 m on the mid-Pleistocene terrace, with probable RSL being somewhat lower.

scholarly journals Age constraints on surface deformation recorded by fossil shorelines at Cape Range, Western Australia: Reply

2021 ◽  
Author(s):  
Michael R. Sandstrom ◽  
Michael J. O’Leary ◽  
Milo Barham ◽  
Yue Cai ◽  
E. Troy Rasbury ◽  
...  
Keyword(s):  
Sea Level ◽  
Western Australia ◽  
Surface Deformation ◽  
Last Interglacial ◽  
Extensive Analysis ◽  
Northern Half ◽  
Age Constraints ◽  
Southern Section

Whitney et al. (2021) challenge our conclusions about rates of deformation and amount of uplift along the Cape Range, Western Australia, particularly the elevation constraints we place on the last interglacial shoreline along the northern half of Cape Range. They selectively focus almost entirely on the northern half of Cape Range, completely omitting our extensive analysis of the southern section, which provides the bulk of our paleo−sea-level interpretations. They also raise concerns about some of the nomenclature and methodology used. We thank them for the opportunity to clarify our results on the minor section of our paper they take issue to, and address their concerns below point by point.

scholarly journals The 2018 Lake Muir earthquake sequence, southwest Western Australia: rethinking Australian stable continental region earthquakes

2019 ◽  
Author(s):  
Dan J. Clark ◽  
Sarah Brennand ◽  
Gregory Brenn ◽  
Trevor I. Allen ◽  
Matthew C. Garthwaite ◽  
...  
Keyword(s):  
Western Australia ◽  
Surface Deformation ◽  
Vertical Displacement ◽  
Strike Slip ◽  
Double Difference ◽  
Surface Rupture ◽  
Field Mapping ◽  
Scaling Relationships ◽  
Magnitude Scaling ◽  
Stable Continental Region

Abstract. Modern geodetic and seismic monitoring tools are enabling the study of moderate-sized earthquake sequences in unprecedented detail. Here we use a variety of methods to examine surface deformation caused by a sequence of earthquakes near Lake Muir in southwest Western Australia in 2018. A shallow MW 5.3 earthquake on the 16th of September 2018 was followed on the 8th of November 2018 by a MW 5.2 event in the same region. Focal mechanisms for the events suggest reverse and strike-slip rupture, respectively. Interferometric Synthetic Aperture Radar (InSAR) analysis of the events suggests that the ruptures are in part spatially coincident. Field mapping, guided by the InSAR results, reveals that the first event produced an approximately 3 km long and up to 0.5 m high west-facing surface rupture, consistent with slip on a moderately east-dipping fault. Double difference hypocentre relocation of aftershocks using data from rapidly deployed seismic instrumentation confirms an east-dipping rupture plane for the first event, and shows a concentration located at the northern end of the rupture where the InSAR suggests greatest vertical displacement. The November event resulted from rupture on a northeast-trending strike-slip fault. UAV-derived digital terrain models (differenced with pre-event LiDAR) reveal a surface deformation envelope consistent with the InSAR for the first event, but could not discern deformation unique to the second event. New rupture length versus magnitude scaling relationships developed for non-extended cratonic regions as part of this study allow for the distinction between “visible” surface rupture lengths (VSRL) from field-mapping and “detectable” surface rupture lengths (DSRL) from remote sensing techniques such as InSAR, and suggest longer ruptures for a given magnitude than implied by commonly used scaling relationships.

A pre-cursor extensive Miocene reef system to the Rowley Shoals reefs, Western Australia: evidence for structural control of reef growth or natural hydrocarbon seepage?

2009 ◽  
Vol 49 (1) ◽  
pp. 337 ◽  
Author(s):  
Georgina Ryan ◽  
George Bernardel ◽  
John Kennard ◽  
Andrew T Jones ◽  
Graham Logan ◽  
...  
Keyword(s):  
Sea Level ◽  
Fault Zone ◽  
Western Australia ◽  
Growth Phase ◽  
Late Miocene ◽  
Structural Control ◽  
Middle Miocene ◽  
Reef Growth ◽  
Sea Level Changes ◽  
North West

Numerous Miocene reefs and related carbonate build-ups have been identified in the Rowley Shoals region of the central North West Shelf, offshore Western Australia. The reefs form part of an extensive Miocene reef tract over 1,600 km long, which extended northward into the Browse and Bonaparte basins and southward to North West Cape in the Carnarvon Basin—comparable in length to the modern Great Barrier Reef. Growth of the vast majority of these Miocene reefs failed to keep pace with relative sea-level changes in the latest Miocene, whereas reef growth continued on the central North West Shelf to form the three present-day atolls of the Rowley Shoals: Mermaid, Clerke and Imperieuse reefs. In the Rowley Shoals region, scattered small build-ups and local reef complexes were first established in the Early Miocene, but these build-ups were subsequently terminated at a major Mid Miocene sequence boundary. Widespread buildups and atoll reefs were re-established in the Middle Miocene, and the internal stacking geometries of the reefs appear to relate to distinct growth phases that are correlated with eustatic sea-level fluctuations. These geometries include: a basal aggradational buildup of early Middle Miocene age; a strongly progradational growth phase in the late Middle to early Late Miocene that constructed large reef atolls with infilling lagoon deposits; and a back-stepped aggradational growth phase that formed smaller reef caps in the early–latest Late Miocene. Growth of the majority of the reefs ceased at a major sea-level fall in the Late Miocene (Messinian), and only the reefs of the present-day Rowley Shoals (Mermaid, Clerke and Imperieuse reefs, as well as a drowned shoal to the southwest of Imperieuse Reef) continued to grow after this event. Growth of the Rowley Shoals reefs continued to keep pace with Pliocene-Recent sea-level changes, whereas the surrounding shelf subsided to depths of 230–440 m. We conclude that initial reef growth in the Rowley Shoals region was controlled by transpressional reactivation and structuring of the Mermaid Fault Zone during the early stage of collision between the Australian and Eurasian plates. During this structural reactivation, seabed fault scarps and topographic highs likely provided ideal sites for the initiation of reef growth. The subsequent growth and selective demise of the reefs was controlled by the interplay of eustatic sea-level variations and differential subsidence resulting from continued structural reactivation of the Mermaid Fault Zone. In contrast to models proposed in other regions, there is no direct evidence that active or palaeo hydrocarbon seepage triggered or controlled growth of the Rowley Shoals reefs or their buried Miocene predecessors.

U-Series Dating of Last Interglacial High Sea Stands: Barbados Revisited

1990 ◽  
Vol 33 (2) ◽  
pp. 129-147 ◽  
Author(s):  
Teh-Lung Ku ◽  
M. Ivanovich ◽  
Shangde Luo
Keyword(s):  
Sea Level ◽  
Uranium Isotopes ◽  
Acropora Palmata ◽  
Sea Level Changes ◽  
Last Interglacial ◽  
Sea Levels ◽  
Oxygen Isotope Stage ◽  
Temporal Relationships ◽  
Multiple Measurements ◽  
Level Model

AbstractU-series chronologies of the emerged coral limestone terraces on Barbados, West Indies, together with those of the terraces from New Guinea, have formed the basis for most late Pleistocene eustatic models. The so-called “Barbados sea level model” has been challenged in recent years, however. A major issue is whether during oxygen isotope stage 5e, when Rendezvous Hill reef complex on Barbados Island formed, the sea rose above the present position for one relatively brief period of <10,000 yr, or for two or more periods spanning approximately from 140,000 to 115,000 yr B.P. Evidence for the latter scenario has not come from initial studies of Barbados but from elsewhere; it is also inconclusive because of the dating uncertainties involved. We have carried out careful redeterminations of U-series ages on a suite of 29 Acropora palmata samples systematically collected from four of the lowest terraces on the island. Diagenetic disturbance may have caused the age spreads at some sampling outcrops. A model for the diagenetic exchange of uranium isotopes in coral samples with those in groundwater explains the anomalous 234U/238U ratios in samples with apparently unaltered mineralogy (aragonite) and trace element (Mg and Sr) chemistry. It shows that age dispersions of 5–10% can be engendered by a U exchange coefficient of the order of 10−6 yr−1. The lower-limit terrace ages, estimated from averaging the multiple measurements, are 81,000 ± 2000 yr (Worthing), 105,000 ± 1000 yr (Ventnor), 120,000 ± 2000 yr (Maxwell), and 117,000 ± 3000 yr (Rendezvous Hill). No evidence was found of previously inferred bipartite sea levels centering around 118,000 and 135,000 yr ago. This study documents the need of dating coral with the high precision/sensitivity mass-spectrometric techniques for future resolution of the temporal relationships among sea level changes, climate oscillations, and astronomical forcing—relationships originally addressed by the Barbados sea level model.

scholarly journals Age constraints on surface deformation recorded by fossil shorelines at Cape Range, Western Australia: Comment

2021 ◽  
Author(s):  
Beau Whitney ◽  
James Hengesh ◽  
Dan Clark
Keyword(s):  
Western Australia ◽  
Surface Deformation ◽  
Tectonic Uplift ◽  
Tectonic Deformation ◽  
Last Interglacial ◽  
Marine Terraces ◽  
Age Constraints ◽  
Western Limb

Sandstrom et al. (2020) present new elevation and age data for a flight of four marine terraces preserved along the western limb of the Cape Range anticline in western Australia. Their interpretation of these data provides an alternative estimate for the amount of tectonic deformation that has occurred since terrace formation. They conclude that less tectonic uplift has occurred in the region than previously reported and posit that their study provides a template for reducing the uncertainty associated with last interglacial paleoshoreline reconstructions.

THE MARINE TERRACES OF SANTA CRUZ ISLAND, CALIFORNIA: IMPLICATIONS FOR GLACIAL ISOSTATIC ADJUSTMENT MODELS OF LAST-INTERGLACIAL SEA-LEVEL HISTORY

2020 ◽  
Author(s):  
Daniel Muhs ◽  
◽  
R.R. Schumann ◽  
Lindsey T. Groves ◽  
Kathleen R. Simmons ◽  
...  
Keyword(s):  
Sea Level ◽  
Glacial Isostatic Adjustment ◽  
Last Interglacial ◽  
Santa Cruz Island ◽  
Santa Cruz ◽  
Isostatic Adjustment ◽  
Marine Terraces

scholarly journals Reservoir-Induced Land Deformation: Case Study from the Grand Ethiopian Renaissance Dam

2021 ◽  
Vol 13 (5) ◽  
pp. 874
Author(s):  
Yu Chen ◽  
Mohamed Ahmed ◽  
Natthachet Tangdamrongsub ◽  
Dorina Murgulet
Keyword(s):  
Land Surface ◽  
Large Scale ◽  
Surface Deformation ◽  
Vertical Displacement ◽  
Nile River ◽  
Reservoir Volume ◽  
Novel Approach ◽  
Land Deformation ◽  
Large Scale Land ◽  
The Impact

The Nile River stretches from south to north throughout the Nile River Basin (NRB) in Northeast Africa. Ethiopia, where the Blue Nile originates, has begun the construction of the Grand Ethiopian Renaissance Dam (GERD), which will be used to generate electricity. However, the impact of the GERD on land deformation caused by significant water relocation has not been rigorously considered in the scientific research. In this study, we develop a novel approach for predicting large-scale land deformation induced by the construction of the GERD reservoir. We also investigate the limitations of using the Gravity Recovery and Climate Experiment Follow On (GRACE-FO) mission to detect GERD-induced land deformation. We simulated three land deformation scenarios related to filling the expected reservoir volume, 70 km3, using 5-, 10-, and 15-year filling scenarios. The results indicated: (i) trends in downward vertical displacement estimated at −17.79 ± 0.02, −8.90 ± 0.09, and −5.94 ± 0.05 mm/year, for the 5-, 10-, and 15-year filling scenarios, respectively; (ii) the western (eastern) parts of the GERD reservoir are estimated to move toward the reservoir’s center by +0.98 ± 0.01 (−0.98 ± 0.01), +0.48 ± 0.00 (−0.48 ± 0.00), and +0.33 ± 0.00 (−0.33 ± 0.00) mm/year, under the 5-, 10- and 15-year filling strategies, respectively; (iii) the northern part of the GERD reservoir is moving southward by +1.28 ± 0.02, +0.64 ± 0.01, and +0.43 ± 0.00 mm/year, while the southern part is moving northward by −3.75 ± 0.04, −1.87 ± 0.02, and −1.25 ± 0.01 mm/year, during the three examined scenarios, respectively; and (iv) the GRACE-FO mission can only detect 15% of the large-scale land deformation produced by the GERD reservoir. Methods and results demonstrated in this study provide insights into possible impacts of reservoir impoundment on land surface deformation, which can be adopted into the GERD project or similar future dam construction plans.

scholarly journals Late Quaternary Landscape Dynamics at the La Spezia Gulf (NW Italy): A Multi-Proxy Approach Reveals Environmental Variability within a Rocky Embayment

Water ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 427
Author(s):  
Veronica Rossi ◽  
Alessandro Amorosi ◽  
Marco Marchesini ◽  
Silvia Marvelli ◽  
Andrea Cocchianella ◽  
...  
Keyword(s):  
Sea Level ◽  
Environmental Variability ◽  
Late Quaternary ◽  
Landscape Dynamics ◽  
Last Interglacial ◽  
Core Depth ◽  
Coastal Bay ◽  
Nw Italy ◽  
Global Sea Level ◽  
Geomorphological Features

The Gulf of La Spezia (GLS) in Northwest Italy is a rocky embayment with low fluvial influence facing the Mediterranean Sea. Past landscape dynamics were investigated through a multi-proxy, facies-based analysis down to a core depth of 30 m. The integration of quantitative ostracod, foraminifera, and pollen analyses, supported by radiocarbon ages, proved to be a powerful tool to unravel the late Quaternary palaeoenvironmental evolution and its forcing factors. The complex interplay between relative sea-level (RSL), climatic changes, and geomorphological features of the embayment drove four main evolution phases. A barrier–lagoon system developed in response to the rising RSL of the Late Pleistocene (likely the Last Interglacial). The establishment of glacial conditions then promoted the development of an alluvial environment, with generalised erosion of the underlying succession and subsequent accumulation of fluvial strata. The Holocene transgression (dated ca. 9000 cal year BP) caused GLS inundation and the formation of a low-confined lagoon basin, which rapidly turned into a coastal bay from ca. 8000 cal year BP onwards. This latter environmental change occurred in response to the last Holocene stage of global sea-level acceleration, which submerged a morphological relief currently forming a drowned barrier-island complex in the embayment.

Sedimentology, faunal content and pollen record of Middle Pleistocene palustrine and lagoonal sediments from the Peri-Adriatic basin, Abruzzi, eastern central Italy

2016 ◽  
Vol 86 (3) ◽  
pp. 359-372 ◽  
Author(s):  
Pierluigi Pieruccini ◽  
Claudio Di Celma ◽  
Federico Di Rita ◽  
Donatella Magri ◽  
Giorgio Carnevale ◽  
...  
Keyword(s):  
Shallow Water ◽  
Sea Level ◽  
Central Italy ◽  
Freshwater Wetlands ◽  
Middle Pleistocene ◽  
Pollen Record ◽  
Vegetation Development ◽  
Oxygen Isotope Stage ◽  
Open Forest ◽  
Facies Succession

AbstractA 25 m-thick outcrop section exposed at Torre Mucchia, on the sea-cliff north of Ortona, eastern central Italy, comprises a rare Middle Pleistocene succession of shallow-water and paralic sediments along the western Adriatic Sea. An integrated study of the section, including facies and microfacies analyses, and characterization of paleobiological associations (mollusks, fishes, ostracods, foraminifers and pollen), enable a detailed reconstruction of the paleoenvironmental and paleoclimatic conditions during deposition. The shallow-water deposits include a transgressive, deepening- and fining-upward shoreface to offshore-transition facies succession overlain by a regressive shoreface-foreshore sandstone body with an erosive base and a rooted and pedogenically altered horizon at the top that imply deposition during sea-level fall. This forced regressive unit is overlain by paralic strata forming a transgressive succession comprising palustrine carbonates and back-barrier lagoonal mudstones. The palustrine carbonates exhibit some of the typical features encountered in palustrine limestones deposited within seasonal freshwater wetlands (marl prairies). Following the sea-level rising trend, the freshwater marshes were abruptly replaced by a barrier-lagoon system that allowed deposition of the overlying mud-rich unit. Within these deposits, the faunal assemblages are consistent with a low-energy brackish environment characterized by a relatively high degree of confinement. The pollen record documents the development of open forest vegetation dominated by Pinus and accompanied by a number of mesophilous and thermophilous tree taxa, whose composition supports a tentative correlation with Marine Oxygen Isotope Stage 17. The new pollen record from Torre Mucchia improves our understanding of the vegetation development in the Italian Peninsula during the Middle Pleistocene and sheds new light on the role played by the most marked glacial periods in determining the history of tree taxa.

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