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Table of Contents - Special Paper 400

Collisional Delamination in New Guinea: The Geotectonics of Subducting Slab Breakoff

by Mark Cloos, Benyamin Sapiie, Andrew Quarles van Ufford, Richard J. Weiland, Paul Q. Warren, and Timothy P. McMahon


Abstract 1

Chapter 1. Geology of the Central Range of Western New Guinea
Introduction 3
Geology of Western New Guinea 4
Geologic Framework 4
  Cenozoic Plate-Tectonic Setting 4
  Active Tectonism 4
Magmatism in the Highlands 7
New Guinea Trench — A Reactivating Relict 9
Geologic Transect — Western Central Range 10
  Foreland Basin — Buried Continental Shelf 10
  Foothills — Leading Edge of Central Range Orogenic Belt 13
  Mapenduma Anticline — Thick-Skinned Deformation 13
  Folds in the Southern Central Range — Thin-Skinned Deformation 14
  Ruffaer Metamorphic Belt — Metamorphosed Passive Margin Strata 16
  Irian Ophiolite Belt — Accreted Oceanic Lithosphere 16
Shortening Estimates and Plate-Tectonic Rates 17

Chapter 2. Mechanics of Subducting Slab Breakoff by Collisional Delamination
Lithospheric Delamination 19
Rupture of the Lithosphere 20
  Fracture and Flow 20
  Plastic and Viscous Flow 21
  The Lithosphere: Brittle/Plastic Behavior 22
  The Asthenosphere: Viscous Response 22
Peak Strength in the Crust and Mantle 23
Force Transmission 24
Plate Bending during Subduction 25
Buoyancy of the Lithosphere 26

Chapter 3. Palinspastic Reconstruction of Collisional Delamination in New Guinea
Collisional Delamination — Scaled Cross Sections 29
  25 Ma: Intraoceanic Subduction 31
  15 Ma: Emergence of Isolated Islands 32
  12 Ma: Beginning of the Central Range Orogeny 33
  10 Ma: Thin-Skinned Deformation 34
  8 Ma: Collisional Delamination Begins 35
  6 Ma: Thick-Skinned Deformation and Magmatism 37
  4 Ma: Collisional Delamination Is Complete 37
  2 Ma: Postcollision 39
  Present Day 40
Collisional Delamination and Induced Magmatism 40
Collisional Delamination and Sedimentation 42
Time-Transgressive Orogenesis: Propagating Tear 42
Along-Strike Variations in Structural Style 44
Lithospheric Healing after Delamination 45
Plate Tectonic Changes Related to the Collision Forming New Guinea: Nearby and Transoceanic 45
Conclusions 46
Acknowledgments 46
References Cited 46