Lut Block

The Lut and Helmand blocks, which constitute much of Iran and Afghanistan, are continental pieces that accreted to Eurasia before the Arabian Plate arrived. The older crustal blocks are relatively rigid, whereas the surrounding strata are more easily deformed into mountains and fault zones; a broken, mountainous belt separates the Lut and Helmand blocks. The folded ranges of the Makran region, Iran and Pakistan, bound both the Helmand and Lut blocks on the south. The Nayband fault zone defines the straight, sharp western margin of the Lut block. The Chaman fault zone, which marks the Arabian-Indian plate boundary, lies along the eastern edge of the Helmand block.

SL3-122-2563

This south-southeast view spans the entire Lut block (L), about 450 miles (731 km) from north (left) to south (nearest line of clouds in upper right), and slightly less than 200 miles (325 km) across. The northern half is broken by curved faults that slice the block into segments; the southern half shows little internal deformation. The far edge is capped with active volcanoes,Taftan (T) and Bazman (B), and peaks that rise above 14,000' (4308 m). The linear western margin is the Nayband fault (N), named for Kuh-e-Nayband, 9872' (3038 m), an isolated volcano that rises more than a mile (1.6 km) above the surrounding plains. At the far end of the fault the narrow mountain range widens; the block-margin fault intersects others with a more southeasterly trend near Shahdad (S). (detailed view: STS002-11-142) Between the Lut and Helmand (H) blocks is a deformed mountainous belt (DB). The western Helmand block is at upper left, where small lakes and large dry lake beds occupy the Sistan depression, the low point of the Helmand River drainage that starts near Kabul. In the left foreground is the Great Kavir (Dasht-e-Kavir), a plain punctuated by salt structures.

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