Introduction To Marine Geology io28

Textbook Series for Marine Science and Technology Marine Geology Tianjin University of Science and Technology

REFERENCE •

沈锡昌、郭步英编著 . 海洋地质学 . 武汉：中国地质大 学出版社， 1993.2

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徐茂泉、陈友飞编著 . 海洋地质学 . 厦门：厦门大学出 版社， 1999.2

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王琦、朱而勤 . 海洋沉积学 . 北京：科学技术出版社， 1989

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J. 肯尼特著 . 成国栋等译 . 海洋地质学 . 北京：海洋出 版社， 1992

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科技兴海丛书编辑委员会编 . 海洋探查与资源开发技术 . 北京：海洋出版社， 2001

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国家质量技术监督局发布 . 海洋学术语 - 海洋地质学 . 2001

Why do you study Marine Geology?

Satellite Picture, April , 2005

1. Take Risks; 2. Practice much; 3. Study hard; 4. Laugh often; 5. As possible as in English.

CONTENTS 0 INTRODUCTION; 1 MARINE EXPLORATION; 1.1 EXPLORING THE OCEAN FLOOR ； 1.2 SURVEYING THE SEA BED ； 1.3 GEOLOGIC OBSERVATIONS ； 1.4 OCEAN DRILLING ； 1.5 MAGNETIC SURVEYS ； 1.6 SATELLITE MAPPING ；

2 THE DYNAMIC SEAFLOOR 2.1 LITHOSPHERIC PLATES ； 2.2 OCEANIC CRUST ； 2.3 THE ROCK CYCLE ； 2.4 OCEAN BASINS ； 2.5 SUB MARINE CANYONS ； 2.6 MICROPLATES AND TERRANES ；

3 RIDGES AND TRENCHES 3.1 THE MIDOCEAN RIDGES ； 3.2 THE HEAT ENGINE ； 3.3 SEA FLOOR SPREADING ； 3.4 TRENCHES ； 3.5 THE DEEP-SEA TRENCHES ； 3.6 PLATE SUBDUCTION ；

4 SUBMARINE VOLCANOES 4.1 THE RING OF FIRE ； 4.2 THE RISING MAGMA ； 4.3 ISLAND ARCS ； 4.4 GUYOTS AND SEAMOUNTS ； 4.5 RIFT VOLCANOES ； 4.6 HOT SPOT VOLCANOES ；

5 COASTAL GEOLOGY 5.1 SEDIMENTATION ； 5.2 STORM SURGES ； 5.3 COASTAL EROSION ； 5.4 WAVE IMPACTS ； 5.5 COASTAL SUBSIDENCE ； 5.6 MARINE TRANSGRESSION ； 6 SEA RICHES 6.1 LAW OF THE SEA ； 6.2 OIL AND GAS ；

Marine geology is concerned with the character and history of that part of the earth covered by seawater. The importance of marine geology is evident when we consider that three-fourths of the earth’s surface is covered by water. Areas of concern range from the beach to marine marshes and lagoons, across the continental shelf, and down to the deepest parts of the ocean.

Marine geologists and geophysicists rarely restrict their research to areas below sea level because a considerable body of important information about the history of the earth and the oceans is gained from rocks exposed above sea level.

Marine stratigraphers and paleontologists often examine uplifted marine sediments. Likewise, those interested in the evolution of the oceanic crust often visit oceanic crust. The little of one of the papers by the marine geologist Philip Kuenen [1958] was “ No Geology without Marine Geology.”

The primary aim of marine geology and geophysics is to develop an understanding of the structure of the earth beneath the oceans, the history and character of processes that have shaped the earth beneath the sea, and oceanic and global history itself.

The roles that geophysicists and geologists play in developing this knowledge overlap considerably, although geophysicists traditionally have been more concerned with the earth’s structure, while geologists traditionally have been concerned mainly with the earth’s history. Nevertheless, the discoveries by geophysicists about oceanic structure have directly led to some of our more fundamental advances in knowledge of the history of the earth.

Marine geologists differ from land-based investigators mainly because they use different tools. Because marine geologists are unable to walk over the outcrops directly and sample the ocean floor (except from submersibles), special methods have been developed for submarine sampling.

Virtually all marine research requires a vessel of some sort. Because the methods employed by marine geologists are so different from those of land geologists and because the ocean tends to act as one major geochemical system, the lines along which marine geologists reason tend to be different from those of land geologists.

Marine geologists also differ from marine geophysicists in that they are concerned primarily with the study of rocks and sediments. Geophysicists, on the other hand, work mainly with data related to the earth’s gravity, heat flow, magnetism, earthquakes, and with artificially generated sound waves transmitted through sediment and rock sequences.

Sampling vessel

gallows

winch

Grab bucket

Field work

0 INTRODUCTION Our planet contains so much water that perhaps it would have been better named Oceania. It is the only known body in the Solar System that is surrounded by water filled with unique geologic structures and teeming with a staggering assortment of marine life forms. Some of the strangest creatures on Earth, whose ancestors go back several hundred million years, live on the deep ocean floor. Many undersea ridges host an eerie world that time forgot-a cold, dark abyss consisting of tall chimneys spewing hot, mineralrich water that unusual species previously unknown to science.

The floor of the ocean presents a rugged landscape unmatched anywhere on the continents. Vast undersea mountain ranges much more extensive than those on land crisscross the seabed. Although deeply submerged, the midocean ridges are easily the most prominent features on the planet. The ocean floor is continuously being created at spreading ridges, where molten rock oozes out of the mantle, and destroyed in deepest trenches of the world. The subduction of the ocean crust in deep-sea trenches plays a fundamental role in global tectonics and s for powerful geologic forces that continuously shape the planet. Much of the world’s untapped wealth lies undersea. The seabed therefore offers new frontier for future exploration of mineral resources.

An extraordinary number of volcanoes are hidden under the waves, many more than on the land. Most of the volcanic activity that continually remakes the surface of Earth occurs on the ocean floor. Active volcanoes ri from the bottom of the ocean create the tallest mountains. Most of the world’s islands in fact began as undersea volcanoes that broke the surface of the sea. However, the preponderance of marine volcanoes is not exposed at the surface but spread out on the ocean floor as isolated seamounts.

Chasms that challenge the largest terrestrial canyons plunge to great depths. Massive submarine slides gouge deep depressions into the seabed and deposit enormous heaps of sediment on the ocean floor. Undersea slides also occasionally generate tall waves that pound nearby shores, causing much destruction to seaside communities. Abyssal storms with strong currents sculpt the ocean bottom, churning up huge clods of sediment and dramatically modifying the seafloor. The scouring of the seabed and the deposition of large amounts of sediment results in a highly complex marine geology.

Homework : 1 Why do you want to study Marine Geology? 2 What is the “Marine Geology”?