Geology of Saipan Mariana Islands Part 1
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Geology of Saipan Mariana Islands Part 1. General Geology GEOLOGICAL SURVEY PROFESSIONAL PAPER 280-A Geology of Saipan Mariana Islands Part 1. General Geology By PRESTON E. CLOUD, Jr., ROBERT GEORGE SCHMIDT, and HAROLD W. BURKE GEOLOGICAL SURVEY PROFESSIONAL PAPER 280-A A study of the nature, field relations, and origin of the rock succession on this small but complex \J JL western Pacific island, and of its regional setting and geologic history since Eocene time UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1956 UNITED STATES DEPARTMENT OF THE INTERIOR Fred A. Seaton, Secretary of the Interior GEOLOGICAL SURVEY Thomas B. Nolan, Director For sale by the Superintendent of Documents, U. S. Government Printing Office Washington 25, D. C. - Price ?3.00 (paper covers) GEOLOGICAL SURVEY PROFESSIONAL PAPER 280 Geology of Saipan, Mariana Islands Part 1. General Geology A. General Geology By PRESTON E. CLOUD, JR., ROBERT GEORGE SCHMIDT, and HAROLD W. BURKE Part 2. Petrology and Soils B. Petrology of the Volcanic Rocks By ROBERT GEORGE SCHMIDT C. Petrography of the Limestones By J. HARLAN JOHNSON D. Soils By RALPH J. McCRACKEN Part 3. Paleontology E. Calcareous Algae By J. HARLAN JOHNSON F. Discoaster ajid Some Related Microfossils By M. N. BRAMLETTE G. Eocene Radiolaria By WILLIAM RIEDEL H. Smaller Foraminifera By RUTH TODD I. Larger Fofaminifera By W. STORRS COLE J. Echinoids By C. WYTHE COOKE Part 4. Submarine Topography and Shoal-Water Ecology K. Submarine Topography and Shoal-Water Ecology By PRESTON E. CLOUD, JR. Professional Paper 280 is being published in the foregoing sequence of parts and chapters in CONTENTS Page Page Abstract-__________________________________________ 1 Geologic succession _________________________________ 33 Introduction _______________________________________ 2 Introduction and synopsis________________________ 33 Basis and scope of the report..___________________ 2 Petrographic terminology._______________________ 34 Acknowledgments. ____________________!_________ 3 Primary volcanic rock types__________________ 38 General history of the region.____________________ 3 Rocks and sediments as field associations _ _____ 38 Geographic terminology _________________________ 5 Reference to localities ___________________________ 39 Climate ____________________________________ 6 Thickness estimates_____________________________ 39 Water resources ________________________________ 6 Supposed Eocene.______________________________ 39 Land classification ______________________________ 7 Sankakuyama formation.____________________ 39 Plants and animals._____________________________ 7 Description of the formation _____________ 39 Mineral resources.______________________________ 9 Supplementary descriptions of mapped Previous studies____________________________________ 9 facies-___--__-_-------------------__- 41 Earliest scientific explorations, 1792-1839__------__ 9 Massive dacite flow rock_____-___-___ 41 Mostly dormant interval, 1840-1900- _____________ 10 Vitrophyric and perlitic dacite breccia_ 43 Interval 1900-1920______________________________ 10 Dacitic tuffs___-______________----_ 44 Since 1920_____________________________ _______ 13 Mixed dacitic pyroclasties___________ 45 General comments._____________________________ 14 Eocene __________________-_---------_---___--_- 46 Regional geology___________________________________ 15 Hagman formation-_________________________ 46 Island arcs of the Philippine Sea margins. _________ 15 Description of the formation _____________ 46 Affinities of western Pacific borderlands with Asia___ 18 Supplementary descriptions of mapped Origin of the island arcs _________________________ 20 facies_ ____________________-_-_-----__ 48 Andesite flow rock_ _ _______________ 48 Geomorphology _ ____________________________________ 20 Breccia-tuff facies______ _____________ 49 Introduction and synopsis. ______________________ 20 Conglomerate-sandstone facies________ 50 Material and structural foundations_______________ 21 Densinyama formation. ____________________ 51 Prevailing genetic processes and characteristic re Description of the formation _____________ 51 sults. _____^_________________________________ 23 Supplementary descriptions of mapped Formation and morphology of benches and facies._ ______________________________ 54 scarps._________________________________ 23 Breccia facies_ ____________________ 54 Terrace succession __________________________ 24 Conglomerate-sandstone f acies _ ______ 54 Terrestrial solution and solution features.______ 24 Limestone-conglomerate f acies ________ 56 General considerations.__________________ 24 Matansa limestone,_________________________ 56 Solution ramparts___-__ ____________ 25 Description of the formation _____________ 56 Caves and sinkholes-____________________ 25 Supplementary descriptions of mapped Lateritic weathering_________________________ 26 facies_ _________________-____-------__ 58 Runoff ____________________________________ 26 Basal transitional f acies _ ____________ 58 Stage of development, ___________ _____________ 26 Pink facies_______ __-__---------_ 59 Systematic geomorphology_______________________ 26 White facies______________________ 60 Axial uplands..____________________________ 27 Oligocene_ _____________________________________ 60 Terraced limestone uplands _ ____________ 27 Fina-sisu formation,________________________ 60 Volcanic uplands. ____________________ 29 Miocene_ ______________________________________ 62 Low limestone platforms_____________________ 30 Tagpochau limestone._______________________ 62 Southern platform ___________________ 30 Description of the formation _____________ 62 Eastern platform _______________________ 31 Supplementary descriptions of mapped Northern platform._____________________ 31 subdivisions. _________________________ 68 Low terraced benches_______________________ 31 Donni sandstone member.___________ 68 Magpi benches.________________________ 31 Machegit conglomerate member _____ 71 East coast benches______________________ 31 Transitional facies_ _________________ 72 Laulau benches_________________________ 31 Tuffaceous facies___________________ 72 South coast bench and scarp _____________ 32 Marly facies_________-______-----_- 73 Donni clay hills belt ________________________ 32 Thick residual clays over tuffaceous Southeastern coastal fault ridges______________ 32 and marly facies__________________ 73 Hagman ridge_ ______________________ 32 Rubbly facies_ _____________________ 74 Naftan ridge___________________________ 32 Equigranular facies _________________ 75 Western coastal plain.______________________ 33 Inequigranular facies________________ 75 Coastline, beaches, and offshore features_._____ 33 Sismondia beds.____________________ 76- VI CONTENTS Geologic succession — Continued Page Historical geology—Continued Page 77 Oligocene history and the last of the primary vol Older terrace deposits ___________ 77 canic rocks_________--_---------___--____-___- 102 Description of the unit_ _____ 77 The early Miocene bank sediment complex_________ 102 Supplementary descriptions of mapped Later Miocene and Pliocene-^----.--------.------ 103 subdivisions. _ _ ___________ 77 Definition of the fault pattern._______________ 103 Pleistocene.- _ __________________________________ 78 Emergence, terrace formation, and renewed Mariana limestone.___--__---_________--_--_ 78 faulting__________________________________ 103 Description of the formation _____________ 78 Pleistocene and Recent--__-____-_--_____________ 104 Supplementary descriptions of mapped The older Pleistocene and its reef-complex subdivisions- _________________________ 82 limestones.______________________________ 104 Rubbly facies_ _____________________ 82 Middle(?) Pleistocene terrace formation and Thick residual clays over the rubbly faulting__________________________________ 105 facies_ __ _ ________________________ 82 Late Pleistocene emergence, fringing-reef forma Acropora-rich facies_________________ 82 tion, and latest fault movement-___________ 105 Massive facies______________________ 83 Eustatic shifts of sea level and the most recent Halimeda-rich facies_________________ 84 events, _ _____-_-_-_-_-________----_--_--- 106 Post-Mariana terrace deposits-_______________ 84 References cited.______________-___-_-___---______-- 107 Description of the unit_ _________________ 84 Appendix A. Described sections. ____________________ 113 Supplementary descriptions of subdivisions. 85 Mount Achugau section of the Sankakuyama forma Tanapag limestone.-________________________ 86 tion, _______________-__-___-_--__-____-____-- 113 Pleistocene and Recent-____-_____________.__--_- Talofofo ridge section of the Densinyama formation. 113 Younger terrace deposits.____________________ Tanke cliffs section of the Matansa and Tagpochau Deposits formed by mass wasting.___-_-____-_ 89 limestones ___________________________________ 114 Alluvium and clay wash_---____________--_-- 89 Introductory remarks__ _____________________ 114 Recent._______________________________________ 90 Matansa limestone, white facies______________ 115 Recently elevated limesands._____-__-_--_-___ 90 Tagpochau limestone, inequigranular facies____ 116 Marsh deposits-____________________________ 90 Lower Tertiary e, Heterostegina borneensis Gravel and sand on emerged fringing-reef zone._______________________________ 116 surfaces. _________________________________ 90 Unassigned Tertiary e beds________-_--_- 116 Present reef and beach deposits_______________ 91 Upper