GEOS1211 Lecture 9: GEOS1211 lectures 9 and 10 learning outcomes
14 Jun 2018
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Lectures 9 and 10 learning outcomes
• Describe the main geological units in the Sydney Basin
Common geological structures seen around Sydney-> bedding, folds, faults, joints
Sdes Volai Past-> sills, diatremes, dykes (basaltic)
Rylstone Volcanics-> to the South East of Mudgee there is an elongate belt of arc-related volcanic
rocks with interbedded volcaniclastic sediments known as the Rylstone volcanics. Age: Late
Carboniferous to Early Permian. Contact relationships: the Rylstone Volcanics uncomfortably overlie
metasedimentary rocks of the Ordovician Lue Beds (mainly metamorphosed sandstones and
mudstones). Lower Permian conglomerates and sandstones of the Shoalhaven Group uncomfortably
overlie the Rylstone Volcanics.
Permian sequence
- Late Permian
o Coal measures- coal, shale, sandstone, conglomerate
o Sequence up to 1000m thick
o River delta non-marine to estuarine environment
o Abundant terrestrial plant fossils in places
- Early Permian
o Shallow marine to shoreline environment
o Cold waters with ice rafts
o Siltstone, sandstone, conglomerate
o Abundant marine invertebrate fossils in places
- Narrabeen Group
o Up to 700m thick
o River-delta environment
o Gosford Subgroup
o Newport Formation- interbedded shale/sandstone, conglomerate
o Garie Formation- lithic sandstone, claystone, shale
- Hawkesbury sandstone
o Up to 290m thick
o Most distinctive rock in Sydney (forms mostof the coastline and cliffs)
o Quartz sandstone with minor shale and conglomerate lenses
o Commonly cross-bedded and well-jointed
o Large braided river system
o Shale lenses sometimes contain spectacular fossils
- Wianamatta group
o Up to 120m thick
o Dominantly shale, finely laminated in places
o Bringelly Shale- mostly siltstone/claystone, minor sandstone and coal
▪ Estuary-lake-riversystem
o Minchinbury sandstone- quartz lithic sandstone
▪ Beach-river bar system
o Ashfield shale- shale sandstone, mudstone, siltstone, claystone
▪ River delta system
• Describe the geological history of the Sydney Basin and its depositional environment
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Document Summary
Lectures 9 and 10 learning outcomes: describe the main geological units in the sydney basin. Common geological structures seen around sydney-> bedding, folds, faults, joints. Rylstone volcanics-> to the south east of mudgee there is an elongate belt of arc-related volcanic rocks with interbedded volcaniclastic sediments known as the rylstone volcanics. Contact relationships: the rylstone volcanics uncomfortably overlie metasedimentary rocks of the ordovician lue beds (mainly metamorphosed sandstones and mudstones). Lower permian conglomerates and sandstones of the shoalhaven group uncomfortably overlie the rylstone volcanics. Late permian: coal measures- coal, shale, sandstone, conglomerate, sequence up to 1000m thick, river delta non-marine to estuarine environment, abundant terrestrial plant fossils in places. Early permian: shallow marine to shoreline environment, cold waters with ice rafts, siltstone, sandstone, conglomerate, abundant marine invertebrate fossils in places. Narrabeen group: up to 700m thick, river-delta environment, gosford subgroup, newport formation- interbedded shale/sandstone, conglomerate, garie formation- lithic sandstone, claystone, shale.
