ODP Legacy: Outreach: Press Releases

Ophiolites and Oceanic Crust: New Insights from Field Studies and the Ocean Drilling Program

Geological Society of America Special Paper 349

Edited by Yildirim Dilek, Eldridge Moores, Don Elthon, and Adolphe Nicolas

"Ophiolites are geological windows into the history of the Earth and Earth processes," Dilek and Moores said. "They provide important clues to how ocean basins formed and disappeared in the past and how the dynamic planet Earth's paleogeography (distribution of continental masses and oceans) looked many millions of years ago. The discovery of copper in ophiolitic volcanic rocks in the Mediterranean region ushered in the Bronze Age in the history of human civilizations. Studies of ophiolites have advanced the methods and theories of geology for more than 200 years. This book presents state-of-the-art information on the significance of ophiolites in studying different aspects of the Earth's history."

Since 1972, when the first GSA Penrose Conference on Ophiolites was convened, these unique features have galvanized multinational and multidisciplinary efforts to study and decipher these complexes and their significance for understanding oceanic lithosphere formation.

The second Penrose Conference on ophiolites in 1998 brought together 86 experts in structural geology, tectonics, geophysics, petrology, and geochemistry to explore new advances and discoveries concerning ophiolites and related drilling from the oceanic crust. Special Paper 349 includes 39 papers from this conference plus updated information on the evolution of ophiolites and modern oceanic crust, and integrates new interdisciplinary data from ocean drilling and other studies of in situ oceanic lithosphere with new results from field studies of ophiolite complexes around the world.

Special Paper 349 Table of Contents

Preface		vii
Section I. Ophiolites, Oceanic Crust, and Global Tectonics
1.	Tethyan ophiolites, mantle convection, and tectonic “historical contingency”: A resolution of the “ophiolite conundrum” Eldridge M. Moores, Louise H. Kellogg, and Yildirim Dilek	3
2.	Evidence for subduction-related contamination of the mantle beneath the southern Chile Ridge: Implications for ambiguous ophiolite compositions Marnie E. Sturm, Emily M. Klein, Jill L. Karsten, and Jeffrey A. Karson	13
3.	The ophiolite–oceanic lithosphere analogue: New insights from the Northern Apennines (Italy) Elisabetta Rampone and Giovanni B. Piccardo	21
4.	Significance of serpentine mud volcanism in convergent margins Patricia Fryer, John P. Lockwood, Nathan Becker, Steven Phipps, and Clifford S. Todd	35
5.	Spatial and temporal relationships between ophiolites and their metamorphic soles: A test of models of forearc ophiolite genesis John Wakabayashi and Yildirim Dilek	53
Section II. Oceanic Lower Crust and Upper Mantle
6.	Large mantle upwellings and related variations in crustal thickness in the Oman ophiolite Adolphe Nicolas and Françoise Boudier	67
7.	Lower oceanic crust formed at an ultra-slow-spreading ridge: Ocean Drilling Program Hole 735B, Southwest Indian Ridge Paul T. Robinson, Henry J.B. Dick, James H. Natland, and the ODP Leg 176 Shipboard Party	75
8.	Magmatic and tectonic controls on the evolution of oceanic magma chambers at slow-spreading ridges: Perspectives from ophiolitic and continental layered intrusions Peter Thy and Yildirim Dilek	87
9.	Syntexis and the genesis of lower oceanic crust Jean H. Bédard, Réjean Hébert, Alain Berclaz, and Véronika Varfalvy	105
10.	Can downward flow of dense cumulate slurry through mushy upper gabbros produce lower gabbros at a fast-spreading center? W. Roger Buck	121
11.	Evolution of gabbroic rocks of the Northern Apennine ophiolites (Italy): Comparison with the lower oceanic crust from modern slow-spreading ridges Riccardo Tribuzio, Massimo Tiepolo, and Riccardo Vannucci	129
12.	New insights concerning the influence of water during the formation of podiform chromitite Stephen J. Edwards, Julian A. Pearce, and Jonathan Freeman	139
13.	Gauging stress from mantle chromitite pods in the Oman ophiolite Benjamin Holtzman	149
Section III. Structure and Physical Properties of Upper Oceanic Crust
14.	Dependence of crustal accretion and ridge-axis topography on spreading rate, mantle temperature, and hydrothermal cooling Yongshun John Chen	161
15.	Comparison of volcanic construction in the Troodos ophiolite and oceanic crust using paleomagnetic inclinations from Cyprus Crustal Study Project (CCSP) CY-1 and CY-1A and Ocean Drilling Program (ODP) 504B drill cores Hans Schouten and Charles R. Denham	181
16.	On the boundary between seismic layers 2 and 3: A stress change? Philippe A. Pezard	195
17.	Characterization of the upper oceanic crust using high-resolution seismic amplitude modeling Yue-Feng Sun and David Goldberg	203
Section IV. Hydrothermal Processes
18.	A synthesis of geological and geochemical investigations of the TAG hydrothermal field: Insights into fluid-flow and mixing processes in a hydrothermal system Susan E. Humphris and Margaret K. Tivey	213
19.	Volatiles in mid-ocean ridge environments Deborah S. Kelley and Gretchen L. Früh-Green	237
20.	Lower-crustal cracking front at fast-spreading ridges: Evidence from the East Pacific Rise and the Oman ophiolite Craig E. Manning, Christopher J. MacLeod, and Patricia E. Weston	261
21.	Hydrothermal alteration and fluid fluxes in ophiolites and oceanic crust Jeffrey C. Alt and Damon A.H. Teagle	273
22.	Hydrothermal alteration patterns in supra-subduction zone ophiolites Kathryn M. Gillis and Neil R. Banerjee	283
Section V. Pacific Rim Ophiolites
23.	Macquarie Island: Its geology, structural history, and the timing and tectonic setting of its N-MORB to E-MORB magmatism Rick Varne, Anthony V. Brown, and Trevor Falloon	301
24.	The Timor ophiolite, Indonesia: Model or myth? Ron Harris and Timothy Long	321
25.	Proterozoic–early Paleozoic ophiolites of the Andean basement of southern South America Victor A. Ramos, Mónica Escayola, Diana I. Mutti, and Graciela I. Vujovich	331
26.	Prospecting for ophiolites along the California continental margin Robert G. Coleman	351
27.	Mesozoic assimilation of oceanic crust and island arc into the North American continental margin in California and Nevada: Insights from geophysical data Nicola J. Godfrey and Yildirim Dilek	365
28.	Tectonostratigraphic significance of sedimentary strata occurring within and above the Coast Range ophiolite (California Coast Ranges) and the Josephine ophiolite (Klamath Mountains), northwestern California Emile A. Pessagno, Jr., Donna M. Hull, and Clifford A. Hopson	383
29.	Models for origin and emplacement of Jurassic ophiolites of northern California Raymond V. Ingersoll	395
30.	Geology and geochemistry of the ophiolitic Trinity terrane, California: Evidence of middle Paleozoic depleted supra-subduction zone magmatism in a proto-arc setting Rodney V. Metcalf, E. Timothy Wallin, Keith R. Willse, and Edward R. Muller	403
31.	Sulfide minerals as an indicator for petrogenesis and serpentinization of peridotites: An example from the Hayama-Mineoka belt, central Japan Hiroshi Sato and Yujiro Ogawa	419
Section VI. Ophiolites from the Iapetus, Rheic-Pleionic, Neotethyan, and Indian Oceans		431
32.	Contrasting mantle sequences exposed in the Lewis Hills massif: Evidence for the early, arc-related history of the Bay of Islands ophiolite Günter Suhr and Stephen John Edwards	433
33.	Petrology, tectonics, and hydrothermal alteration of a fossil backarc oceanic crust: Solund-Stavfjord ophiolite complex of the western Norwegian Caledonides—A review Harald Furnes, Kjell Petter Skjerlie, and Yildirim Dilek	443
34.	Early Devonian boninites from the Magnitogorsk arc, southern Urals (Russia): Implications for early development of a collisional orogen Piera Spadea and Jane H. Scarrow	461
35.	Constraints on the formation and emplacement age of western Greek ophiolites (Vourinos, Pindos, and Othris) inferred from deformation structures in peridotites Annie Rassios and Alan G. Smith	473
36.	Petrology and geochemistry of the Shahr-Babak ophiolite, central Iran A. Mohamad Ghazi and A.A. Hassanipak	485
37.	Aswad massif (United Arab Emirates): Archetype of the Oman-UAE ophiolite belt Adolphe Nicolas, Françoise Boudier, K. Michibayashi, and L. Gerbert-Gaillard	499
38.	A new structural profile along the Muscat-Ibra transect, Oman: Implications for emplacement of the Samail ophiolite David R. Gray, Robert T. Gregory, and John McL. Miller	513
39.	Formation and evolution of the western Indian Ocean as evidenced by the Masirah ophiolite: A review Tjerk Peters	525
Index		537

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