Geographical environment of Pengjiang District

1984 Jiangmen suburb was located at 22 31'~ 22 39' north latitude and113 01'~165438 east longitude. It is bordered by Xinhui County in the west, south and north, Zhongshan Ancient Town in the east and Hetang Town in Xinhui County in the northeast. Land area 108 km2. 1February, 1994, the administrative division of suburbs was adjusted, which is located on the north bank of Jiangmen River, Jiangmen City, with latitude 21~ 22 48' north and longitude11~ 37' ~13 6538 east. It faces Jianghai District across the river in the south, and borders Xinhui City in the east, west and north. The land area is 72.36 square kilometers, 28 kilometers from east to west and 27 kilometers from north to south. 1August 1994, the suburb was renamed Pengjiang District, and the land area remained unchanged.

In June, 2002, the three towns of Tanghe, Tangxia and duruan in Xinhui were placed under the jurisdiction of Pengjiang District, and their geographical locations expanded to 22 05 ′ ~ 22 48 ′ north latitude and 65 438+065 438+02 47 ′ ~ 65 438+03 65 438+east longitude. The land area has increased to 324 square kilometers. The Jiangmen section of Xijiang River in the southeast of the jurisdiction faces Nanhai District of Foshan City, Shunde District and Zhongshan Ancient Town respectively. The south faces Jianghai District across the river, and the land is adjacent to Xinhui District. The northwest borders shaping town and Yayao Town of Heshan City. Geological Stratum The strata exposed in Pengjiang area are modern gray-black and gray-yellow silt at the intersection of Quaternary land and sea, which are distributed in low-lying and flat areas such as Tangxia Town, banks of Tianshahe River, North Street, Didong, Canghou and Shazaiwei Street. Lower Cretaceous, distributed in Tangxia and duruan Town; The middle and lower subgroups of the Cambrian Bacun Group are distributed in Tanghe, duruan, Huanshi Town and Chaolian Street. Rock types The basement in Pengjiang area is dominated by sandstone sedimentary rocks of Cambrian Bacun Group, followed by intrusive rocks such as Yanshanian granite. The intrusive rocks are biotite granite in the third stage of Yanshanian period, distributed in the hilly areas of Tangxia and duruan Town. The second Yanshanian granodiorite is distributed in Hezhen hilly area. The tectonic position of Pengjiang area is Yue Zhong sag, a South China fold system, with undeveloped structure, which is manifested as Jiangmen fault: most faults are covered by Quaternary strata, with a length of over 365,438+0 km, and strike northeast, tend to southeast, with an inclination of 30. Faults control the deposition of Mesozoic and Cenozoic strata and are the boundary between Mesozoic and Cenozoic strata and Cambrian Niujiaohe Formation and Songyuan Unit. The rocks in the fault zone are strongly silicified and broken, and fault gouge and mylonitization are developed. The middle and early time-dependent pulse in this belt becomes lenticular due to the influence of late structure. Microscopically, there are three kinds of time in silicified cataclastic rocks: one is vein, which belongs to the late silicification product; The second is the grinding time, which is the product of strong shear crushing; The third kind of timely particles are elongated into eyeball-like and wave-like extinction, which is timely mylonite. Feldspar is obviously broken and strongly altered, and there are also retrogressive and hydrothermal alteration products such as sericite, pyrite and chlorite. According to the rock formation map, the fault was normal fault activity in the early stage and turned to right-lateral translation in the late stage. There is abundant linear information on remote sensing map. Xijiang fault: It is a large-scale regional fault, extending along Xijiang River, with a total length of about 23 kilometers in the jurisdiction, which is northwest-trending, and the area is completely covered by Quaternary strata. It is a normal fault and its growing period is Himalayan.

topography

Pengjiang District is a semi-closed field and semi-hilly area. The overall terrain is high in the northwest and low in the southeast. It rises and falls from northwest to southeast and gradually inclines. The northwest is hilly and mountainous. The altitude of mountain area is less than 500m or the cutting depth is less than 200m. The mountainous areas are mostly distributed in Xijiang River Basin, and the circular V-shaped Gu Duo at the top of the mountain is a U-shaped valley. The highest peak is Chishi Mountain, located in duruan Town, with an altitude of 457.4 meters. There are many plains and river terraces in the southeast of China. This area is mainly composed of first-class terraces, widely distributed in river valleys and composed of modern alluvium. The lower part is gravel or sand layer in contact with bedrock, and the particles become finer upward, usually several meters thick, and the maximum thickness can reach 20 meters. The distribution is 0.2 km ~ 6 km wide, forming a vast alluvial plain, mostly superimposed or folded terraces, which are higher than the normal water level1m ~ 3 m. On the broad platform, it meanders and develops. In Jiangmen section of Xijiang River, there are three islands in the river: Lotus Pond, Chaolian and Australopithecus Island. Pengjiang District is located in the south of the Tropic of Cancer, and belongs to the south subtropical maritime monsoon climate. Winter is short and summer is long, with pleasant climate, abundant rainfall and sunshine. The frost-free period is more than 360 days, and it doesn't snow all year round. 1984 to 2004, the average temperature was 265438 0.8℃.

Spring, late February to late April. The cold air activity weakened, the warm and humid air flow in the south strengthened and pushed northward, and the temperature rose obviously. Precipitation increases, and there are meteorological disasters such as rainstorm and flood. Weak cold air is still active in early spring, and there will be low temperature and rainy weather or cold in late spring.

Summer, from May to 10. The prevailing southwest monsoon is the season with the richest rainfall, heat and sunshine in a year. Strong convection and frequent lightning are also frequent typhoons. During midsummer, controlled by subtropical high, the weather is hot. Affected by typhoons, it often brings a lot of rainfall to the jurisdiction. Around the Dragon Boat Festival, affected by the upper reaches of the Xijiang River, there will be floods or floods in the local area, commonly known as "Dragon Boat Water". The highest temperature is 38.3℃, which appeared in July 2004 1. The lowest temperature 1 1.3℃ appears on1October 30th1988 10.

Autumn, from the end of 10 to the middle of next year 10. Affected by the cold air from the north to the south, the temperature gradually drops, the rainfall decreases, there are many sunny and dry days, and the temperature difference between day and night is large. Strong cold air in early autumn will bring cold dew and windy weather, which is not good for heading and flowering of late rice. There is occasional frost. The extreme maximum temperature is 30.5℃, which occurred on 65438+February 7, 2002. Extreme low temperature 1.8℃ occurred on 199 1 year 65438+February 29th.

In winter, 65438+1from late October to mid-February. The northeast monsoon prevails, and it is the coldest time of the year before and after the great cold, with occasional frost. Influenced by the cold air and humid airflow from the south, low temperature and rainy weather often occur, which affects early rice seedling raising and transplanting.