吉林大学：《地球科学概论》课程PPT教学课件（英文版）Chapter 7：Sediments and Sedimentary Rocks - Archives of Earth’s History

Chapter: Sediments and Sedimentary Rocks Archtvessof Earths History

Chapter 7: Sediments and Sedimentary Rocks: Archives of Earth’s History

Introduction: Sediments In The rock cycle Sediments are transported by Water ■Ice a Wind Gravity. a The transport and deposition of sediments are initial phases of the rock cycle. a The ultimate fate of most sediment is burial and conversion to sedimentary rock

Introduction: Sediments In The Rock Cycle ◼ Sediments are transported by: ◼ Water. ◼ Ice. ◼ Wind. ◼ Gravity. ◼ The transport and deposition of sediments are initial phases of the rock cycle. ◼ The ultimate fate of most sediment is burial and conversion to sedimentary rock

Sedimentation. Stratification and Bedding a Stratification or bedding, is the arrangement of sedimentary particles in layers. Each stratum(plural= strata or bed is a distinct later of sediment The top or bottom surface of a bed is a bedding plane

Sedimentation, Stratification, and Bedding ◼ Stratification or bedding, is the arrangement of sedimentary particles in layers. ◼ Each stratum (plural = strata) or bed is a distinct later of sediment. ◼ The top or bottom surface of a bed is a bedding plane

Sediments Types And Characteristics Three broad classes a Clastic sediment is loose fragments of rock debris produced by physical weathering Sand and clay. a Chemical sediment precipitates from solution in water Calcium carbonate and salt Biogenic sediment is composed of the fossilized remains of plants or animals Coal, oil, and natural gas

Sediments Types And Characteristics ◼ Three broad classes: ◼ Clastic sediment is loose fragments of rock debris produced by physical weathering. ◼ Sand and clay. ◼ Chemical sediment precipitates from solution in water. ◼ Calcium carbonate and salt. ◼ Biogenic sediment is composed of the fossilized remains of plants or animals. ◼ Coal, oil, and natural gas

Characteristics of Clastic Sediment(1) Clastic sediment is divided into four main size classes. a Gravel >2mm Sand 0.0625to2mm Silt 0.0625t00.0039mm Clay <0.0039mm

Characteristics of Clastic Sediment (1) ◼ Clastic sediment is divided into four main size classes: ◼ Gravel >2mm ◼ Sand 0.0625 to 2mm ◼ Silt 0.0625 to 0.0039mm ◼ Clay <0.0039mm

Characteristics of Clastic Sediment(2) a gravel is subdivided into Boulder gravel >256mm Cobble gravel 64 to 256mm Pebble gravel 64 to 2mm

Characteristics of Clastic Sediment (2) ◼ Gravel is subdivided into: ◼ Boulder gravel >256mm ◼ Cobble gravel 64 to 256mm ◼ Pebble gravel 64 to 2mm

Sorting (1) Sorting identifies sediment in terms of the variability in the size of its particles. Poorly sorted (wide range of particle size), Well sorted (range is small). Changes of grain size typically result from fluctuations in the velocity of the transporting agent, such as water or wind

Sorting (1) ◼ Sorting identifies sediment in terms of the variability in the size of its particles. ◼ Poorly sorted (wide range of particle size), ◼ Well sorted (range is small). ◼ Changes of grain size typically result from fluctuations in the velocity of the transporting agent, such as water or wind

Sorting in sediments

Gravel Sand Silt Clay 100 Beach gravel 80 Flood gravel 8@四 60 40 Till Loess 20 DU une sand 0 o 6-4-2-1012345678910 Size-Frequency Curve ΦSize

Size-Frequency Curve

Sorting, Rounding and Sphericity

Sorting, Rounding and Sphericity