The Archaean to Proterozoic igneous rocks of the Pilbara region, Western Australia –internationally significant geology of a globally unique potential geopark

The Pilbara region of Western Australia, covering some 500 km × 500 km, provides a diversity of Archaean to Proterozoic igneous rocks in a relatively compact area that records a younging southward crustal history of igneous activity, sedimentation, early life, tectonics, and metamorphism from the Archaean (3.6–2.7 Ga) to Proterozoic (2.5–1.8 Ga). The igneous rocks are variable in age, types of rocks, and mode of occurrence and, throughout the Precambrian, record varying igneous rock activity that appear related to several age-related geological settings: to north, the Archaean Pilbara Craton consists of a granitoid-and-greenstone complex; in the central region, there are Proterozoic sequences of volcanic rock, volcaniclastic rock, ironstone, chert, dolomite, shale, and intrusive dolerite sills and cross-cutting dolerite dykes; to the south, there are Proterozoic shale, dolomite, and chert with isolated granitic batholiths. Igneous activity begins in the Archaean with mafic and ultramafic volcanism alternating with sedimentation, and then granitoid cratonisation. This was followed by Proterozoic volcanic crustal accretion with mafic volcanic and volcaniclastic rocks, and by dolerite and gabbro sill and dyke intrusions, ending with isolated granite batholithic intrusions. Igneous rocks in the Pilbara region are diverse: komatiite; mafic volcanic/volcaniclastic rocks; basalt; tuff/volcanic breccia/accretionary lapilli; dolerite, gabbro, leucogabbro, pegmatitic gabbro, granite, and adamellite; xenolithic dolerite/gabbro; andesite, dacite, rhyodacite, rhyolite; granitoids: adamellite, monzogranite, syenogranite, granodiorite, tonalite, granite; granophyre; felsic dykes; and felsic porphyry. They are expressed as granitoid batholiths, komatiite and basalt sheets/lenses, mafic volcanic/volcaniclastic rocks in sheets, sills of dolerite, gabbro, ultramafic rocks, and diorite, dykes of dolerite, gabbro, and felsic rocks, structurally-oriented dolerite dyke swarms, tuff/volcanic breccia/accretionary lapilli in sheets/lenses, sheets of dacite, rhyodacite, rhyolite, and andesite, gabbroic plugs, apophyses, and a variety of host-rock to xenolith relationships. Today, the Pilbara region is arid, hence outcrop is excellent and many of these geological features are well exposed. The diversity of Archaean to Proterozoic igneous rocks in a relatively compact and well-exposed area and qualifies it as a globally unique potential Precambrian igneous-rock geopark

The Walpole-Nornalup Inlets System, Western Australia: A case study of a potential estuarine geopark

Unlike other estuaries Nationally in Australia, the Walpole-Nornalup Inlets is unique complex twin-basin ria estuary in the most humid part of Western Australia. The estuary fronts the oceanographically-dynamic Southern Ocean and, with the high annual rainfall, it provides a range of estuarine landforms, estuarine peripheral wetlands, a dynamic sand barrier that records climate changes and, with its microtidal setting, it provides examples of complex riverine-to-marine dynamics such as intra-basinal gyring. A range of geological to estuarine features that are of geoheritage significance and available for exploration and explanation as geotrails include: (1) the Precambrian geology, (2) the stratigraphy of the Cainozoic Werillup Formation, (3) Cainozoic weathering, sedimentation, and climate history, with a very wet climate to produce erosionally-resistant quartz grain lags, (4) Cainozoic to Quaternary formation of a rock tombolo, (5) the complex estuarine shorelines and history, and (6) complex estuarine processes and history. As an ensemble of geological and other natural history features, Walpole-Nornalup Inlets system also provides a case study of a systematic approach, using the Geoheritage Tool-kit, of identifying and evaluating different natural values. This forms the foundation for to baseline monitoring (for environmental management) and tourism to explore through geological time the natural history of this geologically and biologically rich location

The Holocene Becher Point Cuspate Foreland, Western Australia – An internationally significant and globally unique potential geopark

Located in south-western Australia in a distinctive setting sedimentologically, oceanographically, climatically, biologically, and sea-level history context, the Becher Point Cuspate Foreland is globally unique, and is a site of International Geoheritage Significance that has the potential to be developed as a Geopark. The cuspate foreland is part of an extensive shore-parallel Holocene coastal sand system that forms the seaward edge of the Swan Coastal Plain and eastern border of the Rottnest Shelf. It is the largest cuspate foreland complex in Western Australia and one of the largest in the World. Sedimentary accretion in the region began some 7000 years BP with a sea level + 2 m AHD. Since then, attended by a progressive climate change, sea level has steadily fallen to its present position, and sedimentation has built a coastal plain of low beach ridges with wetlands in the swales. Sedimentologically and stratigraphically, the cuspate foreland developed by seagrass bank accretion shoaling to the strand to form beach and beach-ridge/dune deposits capped in the swales by wetland deposits. Key features of the Cuspate Foreland are (1) the accreted Holocene beach-ridge plain, (2) the evolution of Holocene swale wetlands, (3) the Holocene sea level history, (4) Holocene climate history as recorded in the wetlands, and (5) a host of small-scale geological phenomena. The complex of beach ridges and swale wetlands is the basis of a geopark in which coastal plain evolution, wetland evolution, Holocene sea level history, and Holocene climate changes can be explored and explained essentially in an outdoor Museum. To illustrate the richness of the natural history information, from macroscale to microscale, embedded in the Becher Point Cuspate Foreland, we choose, as case studies, two aspects of the area and describe them in a holistic and multi-scalar manner for education and research, and potential thematic geotours

Coastal geoheritage: A hierarchical approach to classifying coastal types as a basis for identifying geodiversity and sites of significance in Western Australia

Identifying sites of coastal geoheritage significance begins with classification of coastal geology and geomorphology. However, classifying coasts for purposes of geoheritage is made difficult due to the complexity, intergradation, and different scales at which coastal features are expressed, with variation potentially present locally or regionally. Also, geoheritage must address geological content as well as coastal geomorphology expressed erosionally and/or sedimentologically, and Earth history as manifested in coastal erosional and stratigraphic products. While geological and environmental settings play important roles in determining regional variation in coastal form and coastal products, or expression of geological content, coasts at the local scale commonly are expressions of one or more of the main processes of (marine) inundation, erosion, and deposition, and/or of subdominant processes of biogenic activity and diagenesis. To address this coastal geodiversity for geoheritage and geoconservation in Western Australia, a three-level scalar hierarchical approach is used. Level 1 identifies the regional geological and environmental setting, i.e., recognising major cratons and basins, and the climatic/oceanographic setting of a coast, which determine regional coastal forms. Level 2 identifies the main coastal types developed by coastforming processes (e.g., marine inundation of pre-existing landforms; coastal erosion; exhuming of older landforms; construction by Holocene sedimentation, coasts formed biogenically, amongst others), as well as coastal types that illustrate Holocene history geomorphically or stratigraphically, or manifest pre-Holocene rock sequences in sea cliffs. Level 3 identifies finer-scale characteristics particular to any coast within its regional setting to develop an inventory of features providing data within the context of the coastal types for comparative geoconservation purposes. All three levels need to be applied to fully categorise coasts for assessing geoheritage values and for geoconservation

Introducing New Guidelines on Geoheritage Conservation in Protected and Conserved Areas

The Cultural Heritage Administration, Republic of Korea, funded the design and publication of the Guidelines on which this paper is based.This paper introduces newly published guidelines on geoheritage conservation in protected and conserved areas within the “IUCN WCPA Best Practice Guidelines” series. It explains the need for the guidelines and outlines the ethical basis of geoheritage values and geoconservation principles as the fundamental framework within which to advance geoheritage conservation. Best practice in establishing and managing protected and conserved areas for geoconservation is described with examples from around the world. Particular emphasis is given to the methodology and practice for dealing with the many threats to geoheritage, highlighting in particular how to improve practice for areas with caves and karst, glacial and periglacial, and volcanic features and processes, and for palaeontology and mineral sites. Guidance to improve education and communication to the public through modern and conventional means is also highlighted as a key stage in delivering effective geoconservation. A request is made to geoconservation experts to continue to share best practice examples of developing methodologies and best practice in management to guide non-experts in their work. Finally, a number of suggestions are made on how geoconservation can be further promoted.Publisher PDFPeer reviewe

King sound and the tide-dominated delta of the Fitzroy river: Their geoheritage values

There are numerous geological and geomorphic features in King Sound and the tide-dominated delta of the Fitzroy River that are of International to National geoheritage significance. Set in a tropical semiarid climate, the delta of the Fitzroy River has the largest tidal range of any tide-dominated delta in the World. Within King Sound, the Quaternary stratigraphy, comprised of early Holocene gulf-filling mud formed under mangrove cover and followed by middle to late Holocene deltaic sedimentation, and the relationship between Pleistocene linear desert dunes and Holocene tidal flat sediment are globally unique and provide important stratigraphic and climate history models. The principles of erosion, where sheet, cliff and tidal creek erosion combine to develop tidal landscapes and influence (mangrove) ecological responses also provide a unique global classroom for such processes. The high tidal parts of the deltaic system are muddy salt flats with groundwater salinity ranging up to hypersaline. Responding to this, carbonate nodules of various mineralogy are precipitated. Locally, linear sand dunes discharge freshwater into the hypersaline salt flats. With erosion, there is widespread exposure along creek banks and low tidal flats of Holocene and Pleistocene stratigraphy, and development of spits and cheniers in specific portions of the coast

Coastal geoheritage: encompassing physical, chemical, and biological processes, landforms, and other geological features in the coastal zone

The coast is one of the most complex environments on the Earth’s surface, being a zone of intersection and interaction of land, sea, groundwater, and atmosphere and the processes therein, and carries processes and products that are either not present or only weakly developed elsewhere. With other matters such as lithology, structure, or geological framework being equal, the coastal zone is one that generally results in greater geodiversity than elsewhere. The range of interacting physical, chemical and biological processes in the coastal zone include: waves, tides, storms, and cyclonic activity (all resulting in erosion, sediment mobility, particle size sorting, sedimentary structures); development of a splash zone; onshore winds resulting in shore-directed wind waves and longshore drift, and in erosion, transport, particle sorting, lag deposits, and dune building; sedimentation mediated physically by fluvial influx, longshore and/or onshore transport, and tidal currents, or biologically by skeletal production; bioerosion; chemical erosion; salt weathering; tidal invasion of coastal sedimentary bodies by seawater; evaporation and transpiration; hydrochemical effects such as solution, or precipitation of carbonates, gypsum, or halite; fresh-water seepage and its effect on ecology and coastal erosion; sediment delivery fluvially; and biological effects including skeletal production, encrustation, biostrome and bioherm building, grain fragmentation, and bioturbation. A significant factor also is the prevailing nature of many of the processes therein. Coasts commonly exhibit shore-normal environmental gradients and hence a graded expression of processes, resulting in variation in complexity and geodiversity in physical, geochemical and biological products across the shore, and variation in fine- to small-scale stratigraphic sequences. To provide a perspective of the expression of any geodiversity of bedrock, and of the diversity and complexity of sedimentary systems in the coastal zone, selected coastal zones are compared with terrestrial environments for specific rock types, and specific sedimentary sequences – while there is overlap, coastal environments present greater complexity and geodiversity of physical, chemical and biological products. Because they interface with oceans, coastal deposits and coastal forms also can record a history of sea level, climate, and oceanic processes. It is the range of sedimentological and erosional features, expressed geomorphologically and stratigraphically along the coast, and their strength of development, that sets coastal geoheritage apart from continental (or inland) geoheritage

Assessing geoheritage values: A case study using the leschenault peninsula and its leeward estuarine lagoon, south-western Australia

To further the disciplines of geoheritage and geoconservation, a Geoheritage "tool-kit" has been developed to systematically compile an inventory at various scales of geological and geomorphological features in a given area, assess their levels of significance, and address whether geoheritage features are treated in isolation or as inter-related suites that should be conserved as an ensemble. The Leschenault Peninsula, a retrograding Holocene dune barrier in south-western Australia, and its leeward estuarine lagoon, provide a case study of the application of this tool-kit. The barrier-and-lagoon is unique in Western Australia and comprises a wide variety of geological and geomorphological features, from large to fine scale, and varying in significance from International to State-wide to Regional. Some key features include: active parabolic dunes; an interface between dunes and estuary that is the most complex sedimentologically, hydrologically, and ecologically in Western Australia; a stratigraphy recording a complex Holocene sea level history; barrier retreat marked by parallel bands of submerged beach rock; and a sheet of calcrete above the water table. In terms of geoconservation, addressing the various features of geoheritage value in this area is best achieved by viewing the system as an integrated geopark of interactive processes, geology, and geomorphology

Geoheritage and geoconservation - History, definition, scope and scale

Geoheritage and geoconservation are concerned with the preservation of Earth Science features, and are important endeavours globally, as reflected in various international and intra-national bodies set up for conservation, with agreements, conventions, and inter-governmental initiatives. Historically, the United Kingdom is considered the birthplace of the discipline of Geology, and with its history and its leadership role in the preservation of geological sites, it is also the birthplace of geoheritage and geoconservation; both endeavours are integral components of education, tourism, planning and environmental management. In addition, in Pan-Europe, and globally under the World Heritage Convention, inventory-based geoconservation has been adopted as a whole-of-government approach. Australia presents an internationally contrasting, and a nationally internally diverse history in the arena of geoconservation. Western Australia, for instance, generally lags the world trend in practicing geoconservation, while Tasmania is a leader in the arena of geoconservation. For this reason, an objective of this paper is to raise the consciousness of Western Australian scientists, planners, and land managers, who are outside the field of geology, to the issues of geoheritage and geoconservation. Geoheritage encompasses global, national, state-wide, and local features of geology, at all scales that are intrinsically important sites or culturally important sites offering information or insights into the evolution of the Earth; or into the history of science, or that can be used for research, teaching, or reference. As geoheritage focuses on features that are geological, the scope and scale of what constitutes Geology, such as its igneous, metamorphic, sedimentary, stratigraphic, structural, geochemical, palaeontologic, geomorphic, pedologic, and hydrologic attributes, needs to be defined - from there, all that is encompassed by this discipline will be involved in geoheritage, and potentially, geoconservation. Geoconservation is the preservation of Earth Science features for purposes of heritage, science, or education. While globally, and to some extent in Australia, there has been identification of sites of geoheritage importance, and development of inventory-based selection of such sites, currently there are no definitions and no framework that addresses the full breadth and scope of what constitutes geoheritage, nor adequate treatment of the matter of scale, both of which are important to identifying sites of significance. Geoconservation should encompass all important geological features from the regional scale to the individual crystal. The various scales useful for dealing with sites of geoheritage significance include regional, large, medium, small, fine, and very fine scales. While significance is noted in many works dealing with geoconservation, to date the various levels of significance, from international to local, have not been adequately addressed or defined. The level of importance attributed to a given feature of geoheritage significance is related to how frequent or common is the feature within a scale of reference, and/or how important is the feature to a given culture. Five levels of significance are recognised in this paper: International, National, State-wide, Regional, and Local

The global geoheritage significance of the Kimberley coast, Western Australia

The Kimberley Coast in north-western Australia is of global geoheritage significance. It is a large-scale ria coast, with a well developed intricate indented rocky shoreline, with local nearshore islands (archipelago), and a distinct suite of coastal sediments. In addition to its intrinsic geoheritage values, its unique geological and geomorphological features are found in an unspoiled wilderness setting in which the ensemble of natural processes are still operating. The Kimberley Coast is cut into Precambrian rocks: the sandstones and basalts of the Kimberley Basin and, in the southern areas, into folded sedimentary rocks and metamorphic rocks of the King Leopold Orogen. The rocks of the region are well exposed along the shore to providing a global classroom by which to study the region's stratigraphy, structure, and lithology. The coastal forms in the Kimberley region have been determined by the structure and lithology of regional geology, interfaces between major geological units, by marine inundation of onshore landforms, and by the sizes, shapes and configuration of rivers, creeks, their tributaries, and other valley tracts in the region. The coast, however, is not just a continuous rocky shore composed of cliffs, and cliffs with benches, as it also has local sediment-filled gulfs and embayments, cliff shores fringed by mangroves, cliff shores with bouldery ribbons in the tidal zone, and stretches of beaches, and in the embayments, muddy tidal flats, spits, cheniers, tidal creeks cut into the tidal flats, and (embayment-head) alluvial fans. Locally, the coast is composed of algal reefs and coral reefs, beach rock, and various types of tempestites. The Kimberley Coast presents several features of geoheritage significance: 1. with ~ 700 km of (simplified) coastal length, it presents the best and most extensive expression of ria morphology in Australia, and also one of the best developed globally; 2. the occurrence of the shore in a monsoonal subhumid/humid tropical macrotidal setting, with processes distinct to this setting; as a tropical-climate ria, in terms of size and morphology, it is globally unique; 3. the morphology of the shores, variable in form in response to the grain of the country (viz., the Kimberley Basin versus the King Leopold Orogen) and lithology; 4. variation of rocky shores along its length in terms of mesoscale shore types; 5. the sedimentary packages that occur in the region; 6. mangrove-lined rocky shores and embayed shores, with the latter also related to freshwater seepage; and 7. biogenic and diagenetic coasts