Wed. Mar 29th, 2023

ZONE E Origin of Isan

Exhibition of Origin of Isan

Origin and Evolution of Isan

     The land of the current state of Thailand was combined by the movements of two plates (subcontinents) 250 million years ago, which are the Indo-China plates (the Isan region of Thailand, Laos, Cambodia and Vietnam) and Shan-Thai plates (The north of China, Myanmar, Malaysia, the north, center and south of Thailand). 


The collision of the 2 subcontinents the ¨Indo-China Orogeny¨ caused changes.

     Lifting of the collapsed plate formed a curved mountain range. The formation of Shan-Tai caused to a curved mountain range of Sukhothai.

The formation of Indochinese consequence to a curved mountain range of Loei-Phetchabun.

     The subsidence of the geosyncline behind the orogenic belt which perfectly happened is the Khorat Basin.

      Physical weathering of rocks transported and deposited the rocks in the Khorat Basin 160 years ago. When a sedimentary bed was thick, it caused the subsidence, cohesion, formation and became the Khorat Group.

     The subsidence of the Khorat Basin caused the land lower than mean sea level (MSL) in the Early Cretaceous in age. Marine water flowed underground into the Isan Sea. When the endorheic basin happened and the water got dried, it occurred salt crystallization. At the same time, it created the anticline of Phu Pan because of the fold of the land. After that, the deposition caused the Phu Thok Formation. There is petroleum inside.


The Khorat Group 

     The Khorat Group is a Stratigraphic Group located within the Khorat Plateau in the Isan region of Thailand. It is Early Cretaceous in age. It consists of continental freshwater deposits largely of alternating sandstones and mudstones as a group of red stones 250-65 million years ago. They can be divided as 9 types that are the Huai Hin Lat Formation, the Nam Phong Formation, the Phu Kradung Formation, the Phra Wihan Formation, the Sao Khua Formation, the Phu Phan Formation, the Khok Kruat Formation, the Mahasarakham Formation, and the Phu Thok Formation.

     The geologists can analyze the plate tectonics happed in the past from the sedimentary bed of sandstone.

     besides, the bed is full of natural resources which we can use such as

  1. Rock salt and Potash in the Mahasarakham Formation.
  2. Petroleum inside many anticlines.
  3. Metal and nonmetal such as iron, gold, barite, etc.


Psittacosaurus Sattayaraki

     Psittacosaurus sattayaraki is a world’s new dinosaur discovered in Chaiyaphum Province and Kalasin Province for the first time. Sattayaraki is named in honour of Mr. Nares Sattayarak, the geologist who discovered this fossil. The fossil measures 1.6 meters long. It existed in the Early Cretaceous 100 million years ago. It is also called Parrot Dinosaur because its mouth was similar to parrot’s beak, walked on 2 feet, and it was plant-eating dinosaur.


Kinnareemimus Khonkaenensis

  Kinnareemimus khonkaenensis is a world’s new dinosaur discovered at Phu Wiang, Khon Kaen Province. It was from the Early Cretaceous perioa around 130 million years ago. Measured 1.5-2 meters long, Kinnareemimus khonkaenensis was also called Ornithomimosauria because it’s a swift and fast-running dinosaur with no teeth, eating both plants and animals.


Siamotyrannus Isanensis

  Siamotyrannus isanensis is a world’s new dinosaur discovered at the Phu Wiang in Khon Kaen Province. It was estimated the length at 6 – 7 meters and existed in the Early Cretaceous period around 130 – 120 million years ago. Siamotyrannus isanensis was the oldest Tyranosaur found in the world. Walked on its 2 huge and powerful legs. It was also an ancestor of Tyrannosaurus Rex

(T-Rex) which was the biggest meat-eating dinosaur in the North Africa.


The History of Isan

     The northeastern region of Thailand or Isan is a important characteristics combined with civilizations. There was evidence in some human cultures in Prehistory life. In historical era, obviously, there was an urban planning such as the Age of Tawaravadee, Khmer, and The Golden Age of Lan Xang which occurred before they were form as Thailand in the present.


Prehistory (5,600 – 1,600 years ago)

     The Important evidence is Pre-historic Painting discovered in many provinces in Isan. Furthermore, There are many archeological sites such as Ban Non Muang, Ban Pra sart, and Ban Chiang which reflects human society and living.


Dvaravati (1,400 – 1,000 years ago)

     Dvaravati the most ancient branch of Buddhism, which received influence from the central region of Thailand to Isan. An ancient Davaravati kingdom often had a ditch around it. The discovered antiques are historic site, stone inscription, image of Buddha, and Bai Sema (boundary marker of a temple). Bai Sema referred beliefs, richness and ancestor worship. It designated the sacred area.


Khmer Empire (1,400 – 800 years ago)

     The center of the Empire is in Cambodia. The important evidences are stone castles in Nakhon Ratchasima, Buriram, Surin and Sisaket Province. The castles were built of sandstone which was brought from the Phanom Dong Rak Range. The castles were also used as a place for preparing religious rites of both Hinduism and Buddhism. 

     There was a royal road named Rachamankha which was built for connecting the capital city in Cambodia to Nakhon Ratchasima, and it was used as trade route.


The Golden Age of Lan Xang (800 – 200 years ago)

       The center is in Vientiane, Laos. Lan Xang influenced to the north of Isan at first. The important evidence is Cetiya (objects and places used by Theravada Buddhists) with four-sided base style which Pha That Luang in Vientiane was a model for that


Ayutthaya Kingdom – Rattanakosin Kingdom

(300 years ago)

     There was unrest in Laos; it caused migration from Laos to Thailand. Therefore, Laotian started settling down later. In Rattanakosin Kingdom, the king of Thailand had changed this region into the town, district, and the province in the present.


Resources under Isan

     Northeastern of Thailand had evolved from being once sunk and was lower than the mean sea level. The geological evolution since the primitive age caused prominent underground resources which are natural gas fields and rock salt. The resources were incessantly used both in the past and present.


Natural Gas Fields

        Petroleum was derived from the deposition of dead carcasses which died in the sea millions of years ago. These carcasses, when they were buried under deep rocks with high temperatures and pressures, turned out to become oil and gas. There are many natural gas fields in Thailand.

        Mostly are in the gulf of Thailand and in the northeast–having 2 natural gas fields, including:

  1. Nam Phong natural gas field at Nam Phong district, Khon Kaen, and
  2. Sin Phuom natural gas field at Nong Sang district , Udonthani.


        When natural gas fields were drilled from the source, they would be transported to the station to produce gas. Then, natural gas fields are sent to Nam Phong powerhouse to produce electricity.


Natural Rock Salt

     For more than 100 years, northeastern Thailand had been sunk under the sea. In the same time, salts were accumulated in layers of sandstone before they were pushed by the immense pressures from underground to highland. Natural rock salt is approximately two-thirds of the total area.


Mostly are in the gulf of Thailand and in the northeast–having 2 natural gas fields, including:

  1. Nam Phong natural gas field at Nam Phong district, Khon Kaen, and
  2. Sin Phuom natural gas field at Nong Sang district , Udonthani.

     Nowadays, there are factories that produce salt as much as mines which have advance technology. They dig into the ground by drilling rigs, bring water to dissolve rock salt in layer and then bring to a boil and lower the pressure.

     Pumping the salt solution causes land erosion, so when pumping the salt water it’s necessary to bring the water back into the rock layer for prevent such effects and to check the shape of salt frequently. 



     Potash is an industrial mineral containing potassium – mostly found with natural rock salt. More than 80% of potassium that was produced around the world is used in the production of potassium fertilizers. It is one of three main ingredients of chemical fertilizers. It can be found mostly in Baan Tan district, Chaiyaphum and Udonthani.

Benefits: to make fertilizer in chemical industry, glassware processing, and photography accessories

Petrified Wood

    Petrified Wood is fossils of plants that become stone. It is caused by wood that is buried under no oxidizing conditions.

The wood doesn’t rot and is immersed in water that contains silica solution. Silica solution crystallizes, then moved to replace wood while retaining the original wood structure.

Benefits : to make ornamental stones and  garden decorations



    It is an important mineral in the limestone group (CaCO3).

The structure of calcite is usually hexagonal. Some calcite has color and some pieces have not. They can be soluble in acid and has a carbon dioxide bobbling.

Benefits: stone carving and steel works.


    Magnetite is an iron mineral. Formulated as Fe3Og and the structure of magnetite is an Isometric system. Mineral color is black some of the magnetite can be magnetic.

Benefit: to make ore


    The formula of Barite is BaSO4 which also contained Strontium and calcium. The color is yellow and it also doesn’t have any crystalline. Barite has a texture like marble and has a specific gravity of 4.5

Benefits: Used as a filler in paper and textiles; to make barium ore.