Wave-Dominated Lacustrine Facies and Tectonically Controlled Cyclicity in the Lower Carboniferous Horton Bluff Formation, Nova Scotia, Canada

  1. P. Anadón,
  2. Li. Cabrera and
  3. K. Kelts
  1. A. T. Martel and
  2. M. R. Gibling

Published Online: 14 APR 2009

DOI: 10.1002/9781444303919.ch11

Lacustrine Facies Analysis

Lacustrine Facies Analysis

How to Cite

Martel, A. T. and Gibling, M. R. (1991) Wave-Dominated Lacustrine Facies and Tectonically Controlled Cyclicity in the Lower Carboniferous Horton Bluff Formation, Nova Scotia, Canada, in Lacustrine Facies Analysis (eds P. Anadón, Li. Cabrera and K. Kelts), Blackwell Publishing Ltd., Oxford, UK. doi: 10.1002/9781444303919.ch11

Author Information

  1. Department of Geology, Dalhousie University, Halifax, Nova Scotia, B3H 3J5, Canada

  1. Department of Earth Sciences, Parks Road, Oxford OX1 3PR, UK

Publication History

  1. Published Online: 14 APR 2009
  2. Published Print: 6 SEP 1991

ISBN Information

Print ISBN: 9780632031498

Online ISBN: 9781444303919

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Keywords:

  • Lacustrine deposits, occurring in upper Middle Member and Upper Member of Tournaisian Horton Bluff Formation;
  • hummocky cross-stratification (HCS);
  • upper Middle and Upper Members, thicker at Tennyeape;
  • clastic dykes, common within upper Middle and Upper Members;
  • Grey clayshale and claystone, varying from medium grey to black;
  • lacustrine deposits, containing four facies;
  • wave-dominated lacustrine facies and tectonically controlled cyclicity - Lower Carboniferous Horton Bluff Formation

Summary

The Lower Carboniferous (Tournaisian) Horton Bluff Formation was deposited in a tectonically subsiding basin with a major bounding fault (Cobequid Fault precursor) to the north and with onlapping relationships to the south. Excellent exposure of the Middle and Upper Members along the basin axis shows that the members thicken northward and contain repeated shallowing upward cycles formed within a hydrologically open lacustrine system. An ideal cycle shows from base to top: (1) grey clayshale (‘deep’ lake); (2) alternating clayshale/wavy-bedded siltstone and sandstone (lake shoreline), composed of three subfacies (a) lenticular hummocky cross-stratified siltstone (sediment-starved, transitional zone), (b) wave-rippled sandstone (shoaling wave zone), and (c) planar-laminated siltstone (attenuated wave zone); (3) green rooted mudstone (marsh); and (4) tabular and nodular dolomite (early diagenetic subaqueous and pedogenic horizons).

Four types of lacustrine cycle are described: offshore dominated (sediment-starved), shoreline dominated, marsh dominated, and delta dominated. Cycles are thicker and contain fewer marsh-dominated cycles toward the northern basin margin. These trends in cycle type and thickness can be explained by more rapid subsidence toward the fault-bounded, northern basin margin. Cycle thickness decreases upward, reflecting a decreasing rate of tectonic subsidence within the basin.